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Kurt Konrath
Kurt Konrath
When using CA, I gently tap the bottle on desk a few times to help gravity get excess liquid done from the tip, for fine tip extension, you have to hold the end up vertical, maybe leaning against some box or tall object helps.
Put the glue in your refrigerator for half an hour before using it. It makes it less runny.
Yes! Quite so. Also, store your CA in a sealed ziploc plastic sandwich bag in your freezer between uses. This seems to extend the self-life indefinitely. I don't use the stuff unless I absolutely can't avoid it, so I have a bottle at present that's got to be ten years old if not more. I can't remember when I bought it. It's still good. I take it out now and again. Let it return to room temperature. Use a few drops and put it back in the bag in the freezer. I don't know if the ziploc plastic bag has anything to do with it. I used the bag to neutralize my wife's protests about "putting that crap in the refrigerator where the food we eat is kept!"
Are you talking about a pipette or an oem bottle?
Moisture in the air or on the surfaces of objects causes CA to begin hardening, so bagging the bottle will limit how much moisture is available. Cold reduces the reaction substantially, making the glue last much longer.Yes! Quite so. Also, store your CA in a sealed ziploc plastic sandwich bag in your freezer between uses. This seems to extend the self-life indefinitely. I don't use the stuff unless I absolutely can't avoid it, so I have a bottle at present that's got to be ten years old if not more. I can't remember when I bought it. It's still good. I take it out now and again. Let it return to room temperature. Use a few drops and put it back in the bag in the freezer. I don't know if the ziploc plastic bag has anything to do with it. I used the bag to neutralize my wife's protests about "putting that crap in the refrigerator where the food we eat is kept!"
I don’t use the tips that come with the bottles of CA. I pour a tiny amount into a medicine bottle cap and use a fabric pin to apply just the right amount. Better control and no clogged tips. Perhaps a bit wasteful if I over pour it out.
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While we are on the subject of CA glue, it has been said, written, that CA glue only last for 5 to 20 years. I have been building ships longer than that and I have yet to see one of my models fall apart because the glue has failed. Granted I have given away scores of my ships, therefore I cannot attest to the derogation of my really old ships. The ships I still have that old are only about 40 to 50 years and I see no problems with them, except of course dust. Has anyone had a model fall apart because of glue failure? Or is this another "sea story".
Please bear with me while I expound to all and sundry in order to get a pet peeve off my chest.
"Anecdotal evidence," which in the social media environment is often only opinion stated as fact, comes to be repeated in "monkey see, monkey do" fashion until repeated enough that it becomes generally accepted as true. (As famously addressed sixty years ago by the pioneering electronic media theorist, Marshall McLuhan.) Those scale ship modelers who primary rely on the internet to learn the craft are particularly susceptible to the fallacious belief that what "everybody says online" must be correct. In the scale ship modeling arena, this communications phenomenon is particularly apparent concerning the subject of adhesives. Folks frequently post asking which adhesive they should use and just as frequently are given the same shopworn scientifically baseless, and frequently incorrect, answers. The current fad of "watered down `PVA'" is a case in point. The misconception that rigging threads need to be "coated" with diluted "PVA" for protection and to make them "stiffer" is so widespread one might expect "PVA" will soon be touted as a cure for erectile dysfunction as well! The fans of CA adhesive are no differently misinformed, notwithstanding that their "poison of choice" has worked for them... so far.
I don't doubt the accuracy of your reported satisfactory experience using CA as an adhesive on ship models. I haven't had any problems on the very rare occasions I've used it. Such anecdotal evidence is not entirely without merit, as far as it goes, but without scientific proof, it cannot be considered conclusively demonstrated. Fortunately, unlike too many others these days, you are blessed with healthy "critical thinking" skills and ask, "Has anyone had a model fall apart because of glue failure?" Questioning minds are the smartest minds!
The answer to your question is unequivocally, "Yes, I have seen many models fall apart because of glue failure." Having restored hundred-year-old ship models (though usually models no more than fifty years old,) which have been exposed to a variety of deleterious environmental conditions, I'd have to say that the first apparent deterioration in any ship model's fabric will usually be the adhesives. That said, the older the model, the less likely it will exhibit adhesive deterioration because the adhesives used in its original construction are usually those with very strong archival properties. Most pre-WWII vintage models are glued with hide glues, shellac, and/or nitrocellulose cement. Also, of course, most well-built older models will employ adhesives only as a secondary fastening element, with all joints primarily fastened mechanically with a peg or nail, creating a redundant "belt and suspenders" connection. Nevertheless, my anecdotal evidence that ship model glue joints fail is no more scientifically supported than your anecdotal evidence that CA joints don't fail.
Notwithstanding our similar satisfactory experiences, cyanoacrylate adhesives are universally considered unsuitable for meeting "archival" materials quality standards by professionals in the field on the basis of scientific testing. This isn't just some scientist's opinion, let alone yours or mine. It's a fact proven by observation and testing reviewed by peer scientists who have reached a consensus on the validity of the findings. A reliable service life of "one-hundred-years-plus" is the threshold "archival" longevity standard for artifact preservation used by professional conservators and restorationists. CA's primary advantage is its fast-curing time which permits its use for "tacking" pieces together and for this reason CA is best used in together with other slower-curing adhesives which have far better archival properties. The archival reliability of CA adhesives is dependent upon a variety of commonly occurring environmental factors to which ship models are customarily exposed, including, but not limited to, enclosed display cases, humidity changes, and UV light exposure. This fact explains why one "anecdotal observation" is contrary to another. "Correlation does not imply causation."
In addition to CA's archival vulnerabilities, its very poor "reversibility," i.e., the ease of nondestructive disassembly of joined parts for purposes of maintenance and repair, causes its near-universal rejection as suitable for any archival use whatsoever by curatorial professionals. The present consensus of professional curatorial scientists is that the "state of the art" adhesives for use on artifacts such as ship models are 1) Paraloid B-72, 2) clear shellac, 3) natural hide glues, 4) nitrocellulose cement, and 5) polyvinyl alcohol adhesive (primarily for the conservation of paper and cloth,) in that order with the most preferable first. Other adhesives, such as epoxies, may be used on occasion, for specialized applications, of course. Generally speaking, the first criterion for an archivally acceptable adhesive is "Does it stick?" The second, near equally important criterion, is "Does it unstick?" When it comes to adhesive choices, most amateur ship modelers have either "not gotten the memo" yet or for whatever reason don't care how long their work might last.
Since we're talking adhesives, let's resolve "Great PVA Debate" once and for all while we're at it:
On occasion, I've debated the archival properties of "PVA" adhesives such as Titebond and Elmer's Glue which are marketed in the U.S. I have maintained they're archival properties aren't all that good, owing in part to their acid content. Others, including some professional chemist-types, have argued to the contrary, citing multiple online posts and published articles in otherwise respectable ship modeling publications. I've used a lot of Titebond "PVA" in my day, just like almost everybody else. I never could reconcile the conflicting information on the archival qualities of the stuff until now. "The literature," as the academics say, was "all over the place."
After much research, I've discovered that, like just about everybody else who's ever posted online about ship model adhesives, I was a little bit right about "PVA's" acid off-gassing properties, and a lot wrong about "PVA" itself. The confusion comes from the similarity in the names of two different types of polyvinyl adhesive which everybody generically calls "PVA." We've all been like two guys arguing over whether Jello tastes good or not without ever knowing that Jello comes in more than one flavor!
THE WHOLE AMATEUR SHIP MODELING COMMUNITY HAS MISTAKENLY BEEN USING THE WRONG "PVA" ADHESIVE.
These two distinct "PVA's" are widely confused, even by AI search engines, which, of course, only repeat the balance of what data is on the internet, in this case, the blather of all of us in ship modeling forums who share the same "Big Mistake:" One "PVA" has good archival qualities and the other doesn't. The "PVA" that doesn't have good archival qualities is the one just about every amateur ship modeler around has used for years, many mistakenly believing that its archival properties were those of the other "PVA" they weren't using! Yes. I'm serious.
Just saying "PVA" is like just saying "cholesterol" because there's more than one kind. The "Bad PVA" is polyvinyl acetate adhesive, properly known by scientists as "PVAc" and "sold in the U.S. as Titebond and Elmer's Glue. It's also called "white glue" or "wood glue." It's used extensively for a variety of purposes, especially woodworking, but never by professional conservators and restorers because its archival properties are sorely lacking. In fact, it can actually contribute to the deterioration of a cased ship model over time.
The "Good PVA" is polyvinyl alcohol adhesive, properly known by scientists as "PVA" and by curatorial professionals also as "archival-grade PVA," or "archival PVA." This is the only polyvinyl adhesive professional conservators and restorationists use and it's the one scale ship modelers should be using to maximize the archival qualities of our models if we care how well they will withstand the ravages of time.
This confusion of the two types of polyvinyl adhesives extends well beyond the ship modeling community. Below, I have copied a couple of articles which explain far more clearly than I can what the differences between the two polyvinyl adhesives are. If it matters to you at all, do read them.
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Choosing the Right Adhesive: PVA Glue vs. Polyvinyl Acetate (PVAc)
Navigating the world of adhesives can be confusing, especially when terms like PVA and PVAc are used interchangeably or with subtle distinctions. While both Polyvinyl Alcohol (PVA) and Polyvinyl Acetate (PVAc) are polymer-based adhesives with significant overlap in usage, understanding their differences is key to selecting the optimal product for your needs. ...PVAc, or Polyvinyl Acetate, is perhaps the more commonly recognized adhesive, often found in everyday 'white glue' or 'wood glue'. It is synthesized directly from vinyl acetate monomer and is known for its strong adhesion, relatively fast drying time, and ease of use. Many common school glues and woodworking adhesives are PVAc-based. They are generally water-based, making cleanup straightforward.
PVA, or Polyvinyl Alcohol, is chemically distinct. It is typically produced by hydrolyzing PVAc, meaning the acetate groups are replaced with hydroxyl groups. This chemical modification imparts different properties. While PVAc is the direct product of monomer polymerization, PVA is a derivative. This distinction is crucial when considering applications where specific performance characteristics are required.
One of the primary differences lies in their properties related to water. PVA is generally more water-soluble than PVAc, which can be an advantage for applications requiring reversibility or easy cleanup, such as in conservation or certain industrial processes. PVA also tends to exhibit better flexibility and archival stability, meaning it is less prone to yellowing or becoming brittle over time. This makes PVA the preferred choice for archival quality glue for paper and delicate materials.
In terms of applications, PVAc is widely favored for general crafting and woodworking due to its strong initial bond and cost-effectiveness. However, PVA finds its niche in more specialized areas. Its water solubility and reversibility are beneficial in textile sizing and as a component in paper coatings. In conservation, the PVA glue properties of being non-yellowing and flexible are highly valued. The PVA glue vs PVAc debate often resolves based on the need for these specific attributes.
For users seeking a basic, reliable adhesive for everyday crafts or general woodworking, PVAc often suffices. However, when projects demand greater flexibility, superior archival longevity, or specific water-related performance characteristics, PVA emerges as the superior choice. Understanding these nuances allows for informed selection, ensuring that the chosen adhesive meets the project's demands. Whether you're a crafter, a woodworker, or involved in industrial applications, appreciating the subtle yet significant differences between PVA and PVAc is key to achieving optimal results. ...
Choosing the Right Adhesive: PVA Glue vs. Polyvinyl Acetate (PVAc)
Confused between PVA and PVAc glue? This article clarifies the differences, applications, and advantages of Polyvinyl Alcohol (PVA) and Polyvinyl Acetate (PVAc) adhesives.
www.nbinno.com
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The Conservator's Choice: Why PVA Glue is Essential for Archival and Restoration Work
In the delicate and precise world of art conservation and archival preservation, the choice of adhesive is paramount. Materials must be handled with the utmost care, and the adhesives used must not compromise the integrity or longevity of the items being treated. Polyvinyl Alcohol (PVA) glue has long been the conservator's choice for these very reasons, offering a unique blend of properties essential for historical document repair, bookbinding, and artifact restoration. ...The primary reason PVA glue is favored in conservation is its archival quality. Unlike many other adhesives, PVA is formulated to be acid-free and does not yellow or become brittle with age. This ensures that the adhesive itself does not contribute to the deterioration of the valuable materials it holds together. When working with historical documents, photographs, or delicate paper objects, the advantages of PVA glue in terms of long-term stability are non-negotiable.
Another critical property for conservators is the reversibility of the bond. PVA, being water-soluble, can often be gently reactivated with moisture. This allows conservators to painstakingly undo repairs, if necessary, without causing damage to the original material. This controlled reversibility is a significant advantage over more permanent adhesives that can trap materials permanently or cause damage if a mistake is made. The careful polyvinyl alcohol adhesive applications in conservation rely heavily on this controlled reversibility.
Furthermore, PVA provides a strong yet flexible bond. This flexibility is important for materials that might experience slight dimensional changes due to environmental fluctuations, such as humidity or temperature. A rigid adhesive could stress these materials and lead to cracking or delamination. The gentle bonding action of PVA ensures that the original item's structure is not unduly stressed. This is why PVA is often recommended as an archival quality glue for paper and other sensitive substrates.
The application process for PVA glue is also well-suited to conservation work. Its controlled viscosity, often achieved by mixing the powder with purified water, allows for precise application using fine brushes or other specialized tools. The PVA glue properties lend themselves to meticulous work, where only the exact amount of adhesive needed is applied to a specific area.
While PVAc glues are also used in some crafting applications, the specific requirements of conservation and archival work—namely, the need for pH neutrality, long-term stability, and controlled reversibility—often make PVA the superior choice. The careful selection of adhesives is fundamental to preserving our cultural heritage, and PVA glue continues to be an indispensable tool in this critical endeavor. ...
The Conservator's Choice: Why PVA Glue is Essential for Archival and Restoration Work
Discover why PVA glue is the preferred adhesive for art conservators and archivists, focusing on its archival quality, reversibility, and gentle bonding properties.
www.nbinno.com
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There's no point in responding to this post with a lot of excuses for why you don't believe the science (which you can fact check yourself) or don't care about your model lasting longer than you do. If that is where your head is at, there's no question that none of this information should interest you at all. There's no question that CA adhesive or polyvinyl acetate (or "PVAc," as it's properly called) will hold a model together for a good long time and quite often surely for longer than the model's builder will hold together. If you don't think anybody will be interested in enjoying your model after you are gone, I suppose there's no better judge of that than yourself.
If, on the other hand, you aspire to "run with the big dogs" and have an interest in producing the finest models you possibly can, I hope this bit of basic information on scale ship modeling adhesives will be of help to you in that endeavor.
Below is a comparison of the primary adhesives useful in scale ship modeling from a museum curator, restorationist and conservator's perspectives. Few of our models will ever be of interest to any one of those types of professionals, but I find building mine while fantasizing that it might makes researching, designing, and building them even more enjoyable. To that end, I try to pick the best materials for the job, but that's just me.
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Archival Qualities of Cyanoacrylate Adhesives
Cyanoacrylate adhesives, often called “super glue,” are fast-curing, high-strength bonding agents that polymerize rapidly when exposed to trace moisture on surfaces. While they are valued for their speed and versatility, their archival qualities — i.e., long-term stability, resistance to degradation, and suitability for preservation — are limited compared to specialized archival adhesives.Key archival considerations:
- Chemical stability over time:
Cyanoacrylates are generally chemically stable once cured, but they are not inherently archival grade. They can degrade under prolonged exposure to UV light, high temperatures, or certain solvents, which may compromise bond integrity over decades. - Brittleness and impact resistance:
Standard cyanoacrylates are brittle and have poor shock or impact resistance, which can make them unsuitable for objects that may experience mechanical stress over time. This brittleness can lead to microcracking and eventual bond failure. - Gap filling and substrate adhesion:
They bond well to many materials (plastics, metals, rubber, ceramics, wood, glass, paper, cloth, cement, tissue), but their poor gap-filling ability means they are best for flat, closely matched surfaces. In archival work, where surface irregularities or gaps may occur, this can limit their use. - Environmental resistance:
They offer moderate resistance to water and heat, but archival materials often require long-term resistance to humidity, temperature fluctuations, and light. Cyanoacrylates are not designed for the extreme environmental stability needed in museum or library preservation. - Reversibility and removal:
Once cured, cyanoacrylates are difficult to remove without damaging the bonded surfaces. This lack of reversibility is a major drawback in archival contexts, where non-invasive restoration or future disassembly may be necessary. - Specialty formulations:
Some archival or conservation-grade adhesives use modified cyanoacrylates (e.g., elastomer-modified) to improve flexibility and reduce brittleness, but these are niche and not standard in consumer or industrial products.
Cyanoacrylate adhesives are not considered archival adhesives in the strict sense. They are fast, strong, and versatile for many applications, but their brittleness, poor gap filling, and lack of reversibility make them unsuitable for long-term preservation of sensitive or high-value objects. For archival work, specialized adhesives designed for flexibility, reversibility, and environmental stability are preferred.
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Key archival properties:
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1. Natural, non-toxic, and biocompatible
Shellac is a natural resin secreted by the lac insect, composed mainly of polyesters of polyhydroxy aliphatic and sesquiterpene acids. Its biocompatibility and non-toxic nature mean it is safe for use in food, pharmaceutical, and archival materials without introducing harmful residues.
2. Chemical stability and aging behavior
In its acid form, shellac is pH-dependent in solubility and undergoes aging, which increases its glass transition temperature and reduces acid value and solubility. This aging process can make it more rigid over time, which may be beneficial for archival applications requiring dimensional stability.
3. Water resistance
As a water-resistant resin, shellac can protect underlying materials from moisture ingress, a key factor in archival preservation. This property was historically used in wood finishes and electrical insulation to block moisture and maintain integrity.
4. Dielectric properties
Shellac has excellent dielectric properties, making it useful in archival electronics or as a protective coating for sensitive components.
5. Film-forming and adhesive strength
Its ability to form clear, adherent films and seal surfaces makes it effective for encapsulating or protecting archival documents, artworks, and objects from environmental degradation.
6. Biodegradability and sustainability
Shellac is biodegradable and derived from renewable sources, aligning with modern archival practices that favor sustainable, environmentally benign materials.
7. Historical and cultural relevance
Shellac has been used for centuries in coatings, insulations, and decorative finishes, giving it a proven track record in preserving materials over long periods.
Practical archival considerations
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Reversibility and Non-Destructive Repair
One of the most important archival qualities is full reversibility. Unlike many synthetic adhesives, which undergo permanent chemical changes when they cure, hide glue bonds can be cleanly undone with heat and moisture. This allows conservators to disassemble and reassemble objects without damaging the original materials, preserving historical integrity.
Biodegradability and Non-Toxicity
Hide glue is biodegradable and free from synthetic chemicals, making it safe for use on organic materials such as wood, leather, and plant specimens. Its natural origin also means it does not leach harmful substances over time, which is critical for long-term preservation.
Compatibility with Delicate Materials
Because it bonds without damaging the substrate, hide glue is ideal for fine antiques, musical instruments, and botanical mounts. It adheres well to wood and other natural materials without causing discoloration or chemical degradation.
Aging Stability
While not as chemically inert as some modern adhesives, hide glue is stable over centuries when properly applied. Its protein structure resists degradation under normal storage conditions, and its reversibility ensures that future conservation work can be performed without compromising the object.
Historical Authenticity
In archival and museum contexts, hide glue is often preferred because it is historically authentic—it was used in the same way by craftsmen and conservators of the past. This authenticity supports the preservation of original materials and methods.
Limitations
Hide glue is not immune to environmental factors. It can be affected by high humidity, temperature extremes, and prolonged exposure to light. It also has a finite shelf life and can degrade over time, especially if stored improperly.
Summary
For archival purposes, natural hide glue’s reversibility, biodegradability, compatibility with organic materials, and historical authenticity make it a preferred choice for mounting, repairs, and conservation. However, its use requires careful handling and storage to maintain its long-term stability and effectiveness.
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1. Chemical and Structural Basis
Nitrocellulose is formed by nitrating cellulose with a mixture of nitric and sulfuric acids, replacing hydroxyl groups with nitrate ester groups. The degree of nitration (nitrogen content) determines solubility, flammability, and mechanical behavior. For archival applications, low-nitration grades (10.7–12.6% nitrogen) are preferred because they are less energetic, more chemically stable, and form durable, transparent films.
2. Film-Forming and Adhesion Properties
Nitrocellulose cements form hydrogen-bonded networks upon solvent evaporation, producing clear, flexible films with good adhesion to glass, metal, and some plastics. This makes them suitable for sealing microscope slides, preserving photographic emulsions, and bonding archival materials.
3. Long-Term Stability and Degradation
Nitrocellulose is highly flammable (flash point ~4.4 °C) and sensitive to heat, light, and oxygen. In archival storage, it must be kept in a cool, dry, dark environment to minimize degradation and fire risk.
5. Archival Suitability
Nitrocellulose cement’s archival qualities are good for adhesion and clarity but limited by long-term chemical instability. It is best suited for archival work when low-nitration grades are used, stabilizers are present, and strict environmental controls are applied to prevent hydrolysis, oxidation, and fire hazards. For long-term preservation, modern synthetic resins or acrylic-based cements are generally preferred due to superior stability.
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Key archival qualities include:
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Key archival properties
Non-archival PVAc is not approved for use by conservators. It is not considered safe for use on paper, board, and other non-metallic archival materials.
Storage and handling
PVAc adhesives should be stored in a cool, dry place away from direct sunlight and extreme temperatures.
In summary, non-archival-grade PVAc adhesives are not sufficiently stable, reversible, non-yellowing, and non-offgassing, to qualify them as a reliable choice for long-term preservation in libraries, archives, and museums.
Archival Qualities of Paraloid B-72
Paraloid B-72 is a thermoplastic acrylic resin (ethyl methacrylate–methyl acrylate copolymer) widely used in conservation for its durability, reversibility, and resistance to yellowing. Its archival qualities make it a preferred consolidant and adhesive for cultural heritage materials.Key archival properties:
- Chemical stability and reversibility – B-72 is a stable acrylic resin that does not require plasticizers to maintain durability, unlike cellulose nitrate. It is considered reversible in conservation, meaning it can be removed without damaging the underlying object.
- Non-yellowing – It resists discoloration over time, preserving the original appearance of artworks and artifacts.
- Adhesion and flexibility – It adheres well to a range of materials (ceramics, glass, wood, metal) and is more flexible than many other adhesives, allowing it to tolerate stress and strain without cracking.
- Durability – Once cured, it forms a hard, wear-resistant film that is stable under normal environmental conditions.
- Compatibility – It is compatible with vinyl, cellulosic, and silicone resins, and can be used as a barrier layer to protect against pollutants and moisture .
- Environmental resistance – It is insoluble in water and oils, and its water absorption is minimal, making it suitable for use in varying humidity environments.
- Requires careful preparation and application to avoid compromising working properties.
- Solvent choice (acetone is best) and ratios affect setting time and final film properties.
- Not all inks are compatible; some may be disrupted by B-72 solutions.
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Archival Qualities of Shellac
Shellac possesses several archival and preservation-related qualities that make it suitable for long-term storage and use in sensitive applications.1. Natural, non-toxic, and biocompatible
Shellac is a natural resin secreted by the lac insect, composed mainly of polyesters of polyhydroxy aliphatic and sesquiterpene acids. Its biocompatibility and non-toxic nature mean it is safe for use in food, pharmaceutical, and archival materials without introducing harmful residues.
2. Chemical stability and aging behavior
In its acid form, shellac is pH-dependent in solubility and undergoes aging, which increases its glass transition temperature and reduces acid value and solubility. This aging process can make it more rigid over time, which may be beneficial for archival applications requiring dimensional stability.
3. Water resistance
As a water-resistant resin, shellac can protect underlying materials from moisture ingress, a key factor in archival preservation. This property was historically used in wood finishes and electrical insulation to block moisture and maintain integrity.
4. Dielectric properties
Shellac has excellent dielectric properties, making it useful in archival electronics or as a protective coating for sensitive components.
5. Film-forming and adhesive strength
Its ability to form clear, adherent films and seal surfaces makes it effective for encapsulating or protecting archival documents, artworks, and objects from environmental degradation.
6. Biodegradability and sustainability
Shellac is biodegradable and derived from renewable sources, aligning with modern archival practices that favor sustainable, environmentally benign materials.
7. Historical and cultural relevance
Shellac has been used for centuries in coatings, insulations, and decorative finishes, giving it a proven track record in preserving materials over long periods.
Practical archival considerations
- Long-term storage: May require monitoring for stiffness changes due to aging.
- Environmental control: Stable in moderate temperatures and low humidity; avoid prolonged exposure to high heat or strong alkaline conditions.
- Application: Best applied in controlled environments to maintain clarity and adhesion.
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Archival Qualities of Natural Hide Glues
Natural hide glues—made from animal collagen extracted from hides, bones, and connective tissues—possess several properties that make them valuable in archival and conservation contexts.Reversibility and Non-Destructive Repair
One of the most important archival qualities is full reversibility. Unlike many synthetic adhesives, which undergo permanent chemical changes when they cure, hide glue bonds can be cleanly undone with heat and moisture. This allows conservators to disassemble and reassemble objects without damaging the original materials, preserving historical integrity.
Biodegradability and Non-Toxicity
Hide glue is biodegradable and free from synthetic chemicals, making it safe for use on organic materials such as wood, leather, and plant specimens. Its natural origin also means it does not leach harmful substances over time, which is critical for long-term preservation.
Compatibility with Delicate Materials
Because it bonds without damaging the substrate, hide glue is ideal for fine antiques, musical instruments, and botanical mounts. It adheres well to wood and other natural materials without causing discoloration or chemical degradation.
Aging Stability
While not as chemically inert as some modern adhesives, hide glue is stable over centuries when properly applied. Its protein structure resists degradation under normal storage conditions, and its reversibility ensures that future conservation work can be performed without compromising the object.
Historical Authenticity
In archival and museum contexts, hide glue is often preferred because it is historically authentic—it was used in the same way by craftsmen and conservators of the past. This authenticity supports the preservation of original materials and methods.
Limitations
Hide glue is not immune to environmental factors. It can be affected by high humidity, temperature extremes, and prolonged exposure to light. It also has a finite shelf life and can degrade over time, especially if stored improperly.
Summary
For archival purposes, natural hide glue’s reversibility, biodegradability, compatibility with organic materials, and historical authenticity make it a preferred choice for mounting, repairs, and conservation. However, its use requires careful handling and storage to maintain its long-term stability and effectiveness.
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Archival Qualities of Nitrocellulose Cement
Nitrocellulose cement — a cellulose nitrate-based binder — has been used historically in archival and conservation contexts, particularly in early photographic emulsions, microscope slide sealants, and some early adhesives. Its archival qualities are shaped by its chemical structure, physical properties, and long-term stability.1. Chemical and Structural Basis
Nitrocellulose is formed by nitrating cellulose with a mixture of nitric and sulfuric acids, replacing hydroxyl groups with nitrate ester groups. The degree of nitration (nitrogen content) determines solubility, flammability, and mechanical behavior. For archival applications, low-nitration grades (10.7–12.6% nitrogen) are preferred because they are less energetic, more chemically stable, and form durable, transparent films.
2. Film-Forming and Adhesion Properties
Nitrocellulose cements form hydrogen-bonded networks upon solvent evaporation, producing clear, flexible films with good adhesion to glass, metal, and some plastics. This makes them suitable for sealing microscope slides, preserving photographic emulsions, and bonding archival materials.
3. Long-Term Stability and Degradation
- Stability factors: Properly purified nitrocellulose with stabilizers (e.g., diphenylamine) resists premature decomposition.
- Degradation risks: Over time, nitrocellulose can hydrolyze, especially in the presence of moisture, heat, or acidic byproducts. This can lead to yellowing, embrittlement, and loss of adhesion.
- Nitrogen oxide release: If residual acids remain, acid-catalyzed breakdown can occur, producing nitrogen oxides and further instability.
Nitrocellulose is highly flammable (flash point ~4.4 °C) and sensitive to heat, light, and oxygen. In archival storage, it must be kept in a cool, dry, dark environment to minimize degradation and fire risk.
5. Archival Suitability
- Pros: Excellent clarity, strong adhesion, and ability to form thin, uniform films.
- Cons: Requires careful handling and storage; prone to hydrolytic and oxidative degradation over decades.
- Best use cases: Short- to medium-term preservation where transparency and adhesion are critical, and where environmental conditions can be tightly controlled.
Nitrocellulose cement’s archival qualities are good for adhesion and clarity but limited by long-term chemical instability. It is best suited for archival work when low-nitration grades are used, stabilizers are present, and strict environmental controls are applied to prevent hydrolysis, oxidation, and fire hazards. For long-term preservation, modern synthetic resins or acrylic-based cements are generally preferred due to superior stability.
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Archival Qualities of Polyvinyl Alcohol Adhesive (PVA - "Archival-grade PVA") Adhesives
Polyvinyl alcohol (PVA) adhesives, formulated for conservation, are widely regarded as archival-grade materials due to their stability, reversibility, and compatibility with paper and other archival substrates.Key archival qualities include:
- Chemical stability and inertness: Archival PVA adhesives are typically acid-free and do not off-gas once dry, making them safe for long-term use in collections. They are chemically stable under normal storage conditions and do not release harmful volatile compounds.
- Resistance to yellowing: Unlike some synthetic adhesives, archival PVA does not yellow over time, preserving the visual integrity of the bonded materials.
- Non-brittleness with age: When stored in appropriate conditions, archival PVA remains flexible and does not become brittle, which is critical for maintaining the structural integrity of paper and other materials.
- Lay-flat properties: PVA adhesives help minimize curling or waviness in paper by providing a strong yet flexible bond, which is important for preserving the original form of documents.
- Reversibility and re-treatability: PVA adhesives are considered reversible, meaning they can be removed or replaced without damaging the substrate, which is a key requirement for conservation treatments.
- Compatibility: They adhere well to most non-metallic surfaces and are suitable for use in mending, hinging, lining, and other conservation applications.
- Controlled drying: Archival PVA can be formulated to dry clear and flexible, and can be mixed with methyl cellulose to slow drying if needed arcare.com.
- Always use archival-grade (Polyvinyl alcohol) PVA (acid-free, non-yellowing, non-brittling) rather than general-purpose PVAc (Polyvinylacetate,) which may contain additives that could be harmful.
- Store in a cool, dry place away from direct light to maintain stability.
- Avoid over-application to prevent cold flow or excess adhesive seepage into the substrate.
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Archival Qualities of Polyvinyl Acetate Adhesives (PVAc - "White" or "wood glue," "Titebond")
Polyvinyl acetate (PVAc) adhesives are not widely regarded as archival-grade due to their instability, limited reversibility, and incompatibility with paper and other archival materials.Key archival properties
- Chemical stability: Non-archival PVAc adhesives are not typically acid-free and non-offgassing (Oddy tested), meaning they release harmful volatile compounds that could damage sensitive materials. This is of particular concern with artifacts displayed in cases lacking adequate ventilation.
- Resistance to yellowing: PVAc adhesives may discolor over time under normal storage conditions, affecting the appearance of the bonded materials.
- Long-term stability: When stored in an unstable environment, archival PVAc may become brittle with age and lose flexibility.
- Reversibility: Although PVAc adhesives are considered reversible using isopropyl alcohol and/or heat, such reversibility is often difficult, depending upon the length of cure, which jeopardizes its safe removal or re-treatment if needed.
- Lay-flat properties: PVAc's water content may cause paper curling or waviness or raise wood grain, which interferes with maintaining the flatness of paper and wood surfaces.
- Compatibility: PVAc adhesive adheres well to most non-metallic surfaces.
- Drying characteristics: Many PVAc adhesives do not dry clear nor flexible. Neither Titebond Original, Titebond II, nor Titebond III dries clear, and the colors they dry to are influenced by their water-resistance qualities. Titebond Original dries pretty much to its light yellow color; Titebond II will be a darker shade of yellow, and Titebond III will dry to a dark brown.
Non-archival PVAc is not approved for use by conservators. It is not considered safe for use on paper, board, and other non-metallic archival materials.
Storage and handling
PVAc adhesives should be stored in a cool, dry place away from direct sunlight and extreme temperatures.
In summary, non-archival-grade PVAc adhesives are not sufficiently stable, reversible, non-yellowing, and non-offgassing, to qualify them as a reliable choice for long-term preservation in libraries, archives, and museums.
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In the lab, chemicals that were stored in the -10 degree C (freezer) compartment were kept inside another tightly sealed container. The primary reason is that when equilibrating with room temp water vapor in the atmosphere will frost and then melt on the outside of the outer container. This probably happens at an not obvious extent when going from 4 degree (refrig) to RT.
Water is the catalyst for CA. A wet layer on a CA container seems like a good way to have it react too soon or inside the container or both.
WOW. I think I just graduated from Glue School. That was an amazing post, Bob. Thanks for all the research and experience you just contributed!
It was amazing to read and would make a great forum sticky in the Construction section of the forum. 
It was amazing to read and would make a great forum sticky in the Construction section of the forum.
Ich habe noch nie soviel über Klebstoff erfahren und gelernt.Danke dafür
I use medium gap filling generic CA glue marketed under Hobby Lobby and Model Expo. Nothing fancy. It works. Mostly I use Titebond II. So, my models won't be around 3000 years from now, but that's okay.
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Bob, thank you very much for answering my statement on CA glue. What an eye opener. I really don't care how if my models last very long at my age. I also have restored (as a hobby) very old ships in a port town or two, made by merchant mariners. Those ships were very old and the only thing I had to fix was the rigging and a broken yard or mast from clumsy handling. I never saw glue failure, but that is just me observing.
I have another observation if you are willing to wonder about. Removing char to assemble a model., Up until a few years ago I never removed char because I was concerned it would change the dimensions of the part. The glue held and looked good. Now that I began removing char, mainly because the char would show on the finished model. I leave my ships "natural", unpainted, which would cover up char marks. I have heard, read, numerous easy ways to remove char, including scraping with a sharp blade held perpendicular to the char, using vinegar and other chemicals and whatnot, I take this as another "sea story", and finally sanding.
What is your take on removing char.
I have another observation if you are willing to wonder about. Removing char to assemble a model., Up until a few years ago I never removed char because I was concerned it would change the dimensions of the part. The glue held and looked good. Now that I began removing char, mainly because the char would show on the finished model. I leave my ships "natural", unpainted, which would cover up char marks. I have heard, read, numerous easy ways to remove char, including scraping with a sharp blade held perpendicular to the char, using vinegar and other chemicals and whatnot, I take this as another "sea story", and finally sanding.
What is your take on removing char.