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Glycerin-water mix (common in model shipbuilding to increase flexibility)

RickNoyes

RickNoyes

Joined
Mar 4, 2021
Messages
131
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113

Location
Newcastle, NSW, Australia
Hi All

I was looking for something completely unrelated to this topic and got an AI response which intrigued me....

Glycerine-water mix. How to use it for bending thin wood
1. Mix 1 part glycerine with 3–4 parts hot water.
2. Submerge the wood strip fully.
3. Soak:
• Thin strips (1–2 mm): 1–4 hours
• Thicker strips (3–5 mm): overnight
4. Bend around your form.
5. Clamp and let dry completely.
It won’t make the wood rubbery, but it gives you a longer working time and reduces cracking.

I had a quick search of the SOS website and found zero references to this? Although AI said "common in model shipbuilding to increase flexibility". If it was common i thought I'd have found a referance here. AI does tend to hallucinate, which may be the case here, I was wondering if any of you have used this method for assisting in plank bending?

Cheers
Rick
 
RickNoyes said:
Hi All

I was looking for something completely unrelated to this topic and got an AI response which intrigued me....

Glycerine-water mix. How to use it for bending thin wood
1. Mix 1 part glycerine with 3–4 parts hot water.
2. Submerge the wood strip fully.
3. Soak:
• Thin strips (1–2 mm): 1–4 hours
• Thicker strips (3–5 mm): overnight
4. Bend around your form.
5. Clamp and let dry completely.
It won’t make the wood rubbery, but it gives you a longer working time and reduces cracking.

I had a quick search of the SOS website and found zero references to this? Although AI said "common in model shipbuilding to increase flexibility". If it was common i thought I'd have found a referance here. AI does tend to hallucinate, which may be the case here, I was wondering if any of you have used this method for assisting in plank bending?

Cheers
Rick
Click to expand...
will the glue still hold with the glycerine? I would try it out first on some test strips.
 
Glycerin attracts and retains moisture which may keep water based wood glue partially hydrated, preventing it from drying completely. I look forward to the test results, especially if it turns out to be useful for us.
Allan
 
I have used glycerin to soften solid wood veneer to make it less brittle and more flexible for furniture making or restoration. As far as glue, I then use veneer glue to glue it to another substrate such as plywood, but it has to be clamped or vacuumed clamped to fit the shape for at least 24 hours. I'd really be interested to know what glue would work with the glycerine for planking.
 
toliha said:
I have used glycerin to soften solid wood veneer to make it less brittle and more flexible for furniture making or restoration. As far as glue, I then use veneer glue to glue it to another substrate such as plywood, but it has to be clamped or vacuumed clamped to fit the shape for at least 24 hours. I'd really be interested to know what glue would work with the glycerine for planking.
Click to expand...
when you say veneer glue, do you mean contact cement?
 
No, not contact cement....veneer glue is a specifically formulated glue similar to wood glue. It spreads easily seems slightly thinner than typical wood glue but has a longer trying time. You can purchase veneer glue from places like Woodcraft or Rockler.
 
Most reputable mainstream AI search engines provide links citing to the authority for the statements made in the AI generated responses. Check and see what source citations are provided in the referenced AI response. That usually gives you some idea of how authoritative the statement may be. It's not unusual for AI to "repackage" erroneous statements posted on social media platforms, especially if they are repeated often enough. It's good practice to test all AI generated information with the question, "Says who?"
 
I asked Claude AI about this and got this response.

"Good question — the glycerine is the key issue here. It works as a plasticiser by penetrating the wood fibres and disrupting the hydrogen bonds that give wood its rigidity, which is exactly what makes it useful for bending. But that same property creates problems when you want to glue the wood afterwards.

The main concern is that glycerine doesn't evaporate like water does. Water-based treatments will eventually dry out and the wood returns to a glueable state, but glycerine lingers in the wood fibres indefinitely unless actively removed. This means it can interfere with adhesive bonding in a couple of ways — it can prevent the glue from making proper contact with the wood surface, and it can migrate into the glue line over time and weaken the bond.

How much of a problem this actually is depends on which glue you're using. PVA (white or yellow woodworking glue) is probably the most affected, since it relies on penetrating the wood grain and curing as moisture evaporates — glycerine contamination can prevent it from forming a strong mechanical bond. Hide glue, which is traditional in model shipbuilding, has similar vulnerabilities. Cyanoacrylate (super glue) is less dependent on wood porosity and may perform better on treated wood, though surface contamination can still reduce bond strength. Two-part epoxy is probably your best option in this situation, as it doesn't rely on wood penetration and is more tolerant of surface conditions.

The practical solution most model shipbuilders use is to bend and set the wood in its final shape, then allow it to dry thoroughly — sometimes washing the piece with clean water first to help draw out the glycerine, followed by a long drying period. Once the wood is fully dry and the glycerine concentration at the surface is minimal, normal gluing can proceed with better results. Light sanding before gluing also helps by exposing fresh wood fibres.

So it's workable, but you need to be patient about letting the wood fully dry and deglycerinise before gluing, or switch to epoxy if you need to work sooner."
 
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