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Epoxy and plastic don't mix

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El Pirata

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Somebitch! Of all the stupid things I could do I make a blundering novice mistake that I knew would happen. Here's how it goes:

The skull grips for my 45 are made from pewter which I found is too soft to stand up to the punishment of real firearms. So I get a brilliant idea to make some molds of the grips and eithe use epoxy or plastidip for the grips.

Not really a bad idea.

So I go to a chick kinda artsy fartsy store and buy some plaster of paris. While there in the same neck of the woods I see they have some expoy based liquid plastic. I figure WTF and buy it. Instead fo stopping by the hardware store on the way home for some plastidip I opt against it because it's spring and jam packed.

I get home and make the molds nearly flawlessly. I let them continue to harden for a few days and today I say f-it and decide to pour the grips. I opt against using my industrial strength tupperware as a mixing bowl because I figure it's going to need to be an expendible item I use for mixing.

In a cabinet I see some plastic cups that most people associate with beer because you see them at parties all around. They are like really cheap and I figure it ought to work perfectly for what I need. So start mixing add some color, I wanted black but they didn't have black so I used a bunch of blue and red am made a deep purple. I add the hardner and pour it into the mold.

I definately used way to much expoy because the cup is still about halfway full from where it was before mixing. Anyway set the cup down and I hit the head the resume surfing the net. I go check on the epoxy about 20 minutes to see if it's starting to set up and see the bottom of the cup has melted out and the resin in the cup has gone from cup to top of my parts box to CARPET. There's a huge puddle on the freaking carpet.

I am able to clean up most of the stuff off the carpet and my parts box but I know that the carpet is a lost cause anyway. Now to make my good day even better, I am thinking I might have been a little too lenient on the hardner and am praying I was not TOO lenient and the stuff will never dry. I'll post pics later.
 
KIller idea on the molds.. i would like to see the finished product.. when it dries of course lol
 
Kinda makes the spilled ashtray seem a little less significant now, doesn't it?
 
The first set is starting to set up just fine. I unfortunately did have to mix another batch because due to some settling in the molds the first batch was not enough to fill the entire area after it settled. I made a second batch with a a slightly higher amount of hardner so it will help the first batch kick off. Now the long wait until they are done. I'll probably let it harden until way later this evening or tomorrow before I attempt to take it out of the mold.

One thing I need to firgure out is how to get it out of the molds without breaking it. Since the is the initial prototype I am not afraid to break the mold and make a better mold for next time. I just need something that's epoxy friendly so it's easier to get them out next time.

First batch, I know it looks like grape jelly.
CIMG9651.JPG


Second batch.
CIMG9657.JPG
 
Last edited:
Originally posted by Candyman
Kinda makes the spilled ashtray seem a little less significant now, doesn't it?
You're on to something here. Let me check for a warning label on the container about melting other plastics or the such. This one probably comes with a warning that says, "listen schmucks, don't use your beer cups for mixing!"

Originally posted by mcvickj
Is there something you can buy to spray the mold? Like a non stick spray?
I had thought about buying pam specifically for this purpose but I had buck fever and forgot.
 
The cups melted from the chemical, or the heat during the curing process?
I also learned many years ago that you can't pour lacquer thinner into a styrofoam cup.
El P, Pewter is an alloy made from lead and tin. Pretty much the same as solder, but with a higher tin content, but that's why it's soft.
A good release agent for molds is any car wax with Carnuba in it. The paste wax, not the liquid.
 
Instead of using plaster as your mold, try a liquid rubber / latex. If you have been to a chefs shop lately you will see a lot of cooking molds, cup cake, and cake pans made out of this material.
Once your project is set, you just flex it and peel it out.

To get a good black color use some powered graphite in your mixture. You can brush some on your mold as a releasing agent as well.
 
I've got a basic question...how do you make the molds to start out with?
 
Mixed the plaster of paris in a cup then poured into a tupperware. It was supposed to set after about 30 minutes so after 20 I pressed the original grips into the mold.
 
Anyone have a clue how to safely break the molds without damaging the epoxy grips?

Too late I tried it the mook way and broke the grips in the mold.
 
I think you had too much hardener in your mix. It shouldn't have been that brittle. Mix exactly according to the directions, and walk away from it for 24 hours.
You can buy the latex molding rubber in that same artsy-fartsy store. The same mold can be used many times. It's VERY flexible, and is meant to peel away and stretch around odd shapes. That's how they cast chess pieces without a 2 or 3 piece mold.
 
Originally posted by El Pirata
Anyone have a clue how to safely break the molds without damaging the epoxy grips?

Too late I tried it the mook way and broke the grips in the mold.

Did the mook way involve a hammer?
 
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