# How to construct a 12-micron thin layer of powder+epoxy?

Okay, this is more of an engineering tactic question perhaps, but any insight into any possible process will be very, very appreciated. So I'm mixing a powder with epoxy, making a pasty, fluid semi-solid and layering it on a plastic layer. I need alternating layers of plastic (200 microns) and powder+epoxy mix (12 microns). Now 12 microns is too thin, and I'm not sure how I'd go about accomplishing this. The tolerance on this layer is +- 5 microns (maximum). How do I go about making such thin a layer? I have been able to accomplish 35 microns so far, nothing lower, by taping a 35-micron thick tape to the plastic surface, and having that guide my paintbrush, and then sandwich another plastic layer on top. The area of these surfaces can be anything between a 35mm-diamteter circle to a 5" x 5" square sheet. Thanks!

• 12 microns or about half a mil is very thin. You want these powder+epoxy layers to be adhesive layers which hold the surrounding plastic layers together, right? So you're talking about applying a wet powder+epoxy layer directly between two plastic layers and letting the epoxy cure rather than fabricating the finished 12 micron thick powder+epoxy layers separately and then interleaving them with the plastic layers, right? – Samuel Weir Jul 15 '17 at 4:03
• @SamuelWeir yes, you are spot-on with my technique! I'd love any ideas :) – Betsy Jul 15 '17 at 5:38
• I think that you would need to use a very fluid, non-viscous epoxy for such a thin layer. What is the purpose of the powder? To make the epoxy mixture more viscous? If so, then I would say that it probably works against your goal here. Also, what kind of plastic is this? Just simply having a plastic surface that is absolutely flat over a 5"x5" area to within 12 microns is not trivial. Finally, it might help for you to mention the purpose because some problem solutions (like fabricating small supports) may be incompatible with the purpose of this layered composite. – Samuel Weir Jul 15 '17 at 17:12
• Please do not remove essential parts of your question after it has been answered. – ACuriousMind Jul 28 '17 at 21:41