Help with CA glue not bonding oak on oak

[Rob444]

I have been experimenting with the Paranoid B-72 that can apparently be used as an adhesive or a clear seal.


I mixed it (by weight) to a 25% solution in acetone. It can also apparently be resolved in alcohols. It resolves in acetone very slowly. I let it dissolve overnight. In the morning it was a viscous transparent layer on the bottom of the acetone that you could discern because of the different index of refraction. I had to shake it vigoursly for several minutes to get it to mix evenly with the acetone.

I tried it to attach line to some blocks and gluing two pieces of wood together.



The acetone evaporates very quickly. even after clamping the wood together there was no real adhesion between the parts. The line stuck to the block, but I would say much less than if I used PVA glue. I will try using more between the wood pieces to see what happens.

I also bought the suggested fumed silica to mix with it. This is supposed to improve the viscosity and adhesive properties. The silica is an extremely fine dust. It will probably be hard to mix evenly and I will be using my paint hood and a respirator mask before I take it out of the container. I recommend that anyone else who wishes to to experiment with the silica do the same to protect their lungs.



I'll report back in a few days with the results. If I am unhappy with it I will try desolving it in alcohol.

Rob

 

[Pepite 1/60]

Why do poeple insist poisening themselves uselessly?

https://www.highlandwoodworking.com/library/using_hide_glue.pdf

 

[Bob Cleek]

The difficulties you've reported may be related to your preparation and handling methods. For proper mixing and thickening see: https://resources.culturalheritage....ontent/uploads/sites/8/2021/11/osg025-001.pdf

The method of mixing the B72 pellets and the acetone is determinative of the initial thickness of the mixed suspension according to various instructional videos online. (Always to be taken with a grain of salt.) They say that allowing a bag of pellets suspended at the top of the container of solvent to dissolve overnight and fall slowly through the column of solvent, will yield a thicker, and more uniformly dissolved suspension for adhesive applications. Shaking the mixture to more evenly suspend the resin in the solvent is not advised due to issues with air entrapment (bubbles) and the natural slow dissolving properties of the material in the solvent. (Which I presume is science-speak for "Just shaking the stuff doesn't do much good.")

From what I gather, B72 does not like to be mixed forcefully, but rather to "drift down" through the solvent column to create an evenly distributed suspension. If the suspension isn't evenly distributed, the thin material at the top of the container is going to have a different consistency, and therefore different adhesive behavior, than the material that has settled at the bottom oof the container.

This is all from my study. I've yet to get my hands on any of this stuff. So don't take my word for it. As always, "follow the directions on the container." (And online tutorials, as well.)

As for the fumed silica ("Cab-o-sil") I've used plenty of it to thicken various epoxy adhesive and coating materials. Wearing a particulate mask is advisable when mixing. Running a fan in the area is not advisable. Any airflow will blow the stuff all over the place. (Guys in the boatyards call it "pixie dust." ) It's a good all-purpose thickener but when using it to thicken an adhesive, remember that while the silica powder thickens the resin, it does not add any adhesive properties. It will add some structural strength to the adhesive matrix, but it is not "sticky," so realize that a thin solution of B 72, as mixed for use as a sealer or coating, when thickened with silica will not increase the adhesive strength of the thin B 72 mixture.

Watching your reports closely!