Preparation of 28+ Surfaces for Epoxy Adhesive Bonding

An important resource for a DiYer about epoxy bonding :


Some other tips that may help someone.
(Yes I am having a few issues with epoxy & getting a good finish)
Anyone used Agent-F ? is it Xylene & Paraffin wax?

For information to help others. Today I did a hot coat of epoxy, it has turned out 100+% better than the last coat that I spent hours sanding back.
The difference was:

  1. Sanded down the surface to give a surface to bond onto.
  2. Wiped down with Denatured alcohol (AKA Methylated spirits , Metho) waited till 100% dry
  3. Added a mixture of of ~8%paraffin wax & xylene ~5ml per 100ml of epoxy.
  4. After applying the epoxy evenly I walked away, 3 hours later when i went back I was very happy with the surface finish.
    Not sure if it was the surface preparation or the Paraffin/Xylene mix but it has made a huge difference. No fish eyes very clear, glass like finish even before sanding & polishing. may not even sand & polish this coat.
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For a good surface finish:
apply a spray/cloud of acetone with a plant water sprayer to watch the air bubbles escaping from the epoxy surface (cheap method in a well ventilated room)
Degasing the finish epoxy coat before application with a vacuum pump has a nice effect too.

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I do not disagree however, some water sprayers are not accepting of acetone or are just low quality & fail after a few pumps. I will try this method again, as I worry the xylene &wax will reduce the strength by not bonding to the prior layer. Your thoughts ?
I boiled the epoxy when I tried the degassing method. Since then I have started to build a vacuum chamber with a clear lid so I may have better luck next time. Thanks for the advice!

So true. Acetone moltens/dissolves some plastics. Trial and error method here.

Never tested. I wouls ask on a shape forum.

As you may know, it is not a real “boiling” as water boils at 100 degC.This is not a state change so the temperature should not rise (if you don’t do it in the sun). It’s just the air that is removed. So the resin must keep its properties.