Casting epoxy

Bill DeShivs

Bill DeShivs

Knifemaker / Craftsman / Service Provider
Joined
Jun 6, 2000
Messages
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As most of you know, I do knife repair. I often need to patch existing handles, or to cast plastic parts.
I have been using Castin' Craft polyester casting acrylic. It appears to have been discontinued. I like it because it's crystal clear and cures hard-hard enough to sand and polish to a glass-like finish.
Al the epoxies I have tried never fully surface harden, leaving the surface sticky. The factory replacement for the product I have been using doesn't surface harden well, either.
I'm sure someone here knows a solution to my problem.
Of course, I do need to color the material-so that's a consideration.
 
If it doesn't cure you missed the proportions of A and B solution, not mixed well (doubt it) or the room temp is too low. Put it in the oven for an hour or two. Anyway epoxy is softer than acrylic and the shine goes of fast and scratch marks are easy made. I have a guy making those for me (scales) and wood-epoxy looks great but wouldn't have it on my knives. He tried a bunch of epoxies but the shine goes away fast unless care is taken. Same reason I don't like carbon steels. Care! I do not want to care. Personally, I would suggest find another product similar to the one you used.
 
I have had a similar problem. I have used a inlace product from Craft Supplies to fill in images that I cut in my knife handles. Just recently the company apparently went out of business.
So I have had to look for other ways to do the same thing.
So far the best thing I have found is to use g-flex epoxy with turquoise powder mixed in with the epoxy. This sets up hard and I have had satisfactory results using it.
 
It has been a long time, but I used Bar Top (don't recall the maker) and Mirror Cast resin (System Three), to put glass like tops on log-slab tables. It dried hard and sands/polishes well.

There are many like it available if you search under the "countertop epoxy" and "bar top epoxy".
 
Counter top style epoxies can’t be poured deeper that 1/4 inch usually they’re very thick and more difficult to degas.

Alumilite makes some good stuff I can push the normal casting epoxy to 1/2 on small pours. They have a deep pour as well. I’ve tried other brands like super clear but it doesn’t take a polish like alumilite does.
 
I have already ordered some stuff from Alumilite. Looking forward to trying it.
 
Bill, look into surfacing wax. Many resins feel sticky or tacky once cured. When doing lay ups, on the last lay, we add what’s called surfacing wax. It makes it cure up without remaining tacky. You’d have to ask your supplier about your particular product but it’s needed for polyester and vinylesther resins for sure. Some come with it added to the resin and some doesn’t. You’d have to discuss with maker or supplier. Also, explain what you’re experiencing to them. If they any good , they should already know how to fix that.
 
Polyester and vinylester laminating resins are formulated so the surface does not cure fully. That way, subsequent layers can bond to an uncured surface. The final layer (outside) has wax or something similar to seal the the top layer from air which will allow it to cure fully. Casting resin usually has the wax or other surface curing agent already added.
 
Bill DeShivs said:
I have already ordered some stuff from Alumilite. Looking forward to trying it.
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Bill,
I was going to recommend alumilite clear slow when I read your first post. It’s a very good product but as with most chemicals, it’s a strict process and temperature is important if you ever need to do a swirled look without bleeding. Anyway, shoot me a message if you need any support. 👍

John
 
I have done lots of epoxy casting and had the same problem, I second Aluminite.

I think you can buy it locally if you have a Hobby Lobby, Michaels, or other craft store.
 
Thanks, everyone! The casting polyester that I have been using stays tacky for a day or so, and then hardens completely.
 
Bill DeShivs said:
Thanks, everyone! The casting polyester that I have been using stays tacky for a day or so, and then hardens completely.
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You can try a little heat to speed it up. Be careful though as you can make it start to flash some of the lighter compounds and end up with bubbles.
 
I use Rusty Design slow cure by weight. Takes about a week to cure full but I can cast a solid, clear cylinder 2" x 4" tall with very few apparent bubbles. its an epoxy resin, not a polyester though if that makes a difference for you.
 
tattooedfreak said:
I use Rusty Design slow cure by weight. Takes about a week to cure full but I can cast a solid, clear cylinder 2" x 4" tall with very few apparent bubbles. its an epoxy resin, not a polyester though if that makes a difference for you.
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Entropy resins has a slow cure like that it has a 6 hour working time and something like 72 hours until tack free. I like it for certain uses. If you put mica or other things in it most of it settles to the bottom before it cures.
 
Thescrawnylumberjack said:
Entropy resins has a slow cure like that it has a 6 hour working time and something like 72 hours until tack free. I like it for certain uses. If you put mica or other things in it most of it settles to the bottom before it cures.
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I havent had an issue with powders or dyes so far, anything else I have to experiment with first and sometimes do multiple pours. Cure time does vary with thickness and I'll sometimes demold stuff early (like figures or shapes) to position them in ways I cant mold.
 
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