Clear Resin Casting - Possible At Home and Without Pressure Pot?

Hecubus114

Hecubus114

Sr Member
RPF PREMIUM MEMBER
If I want to cast something in clear resin, have no air bubbles, and safely in my own garage without a pressure pot, am I living in a dream? Is there any such product nowadays capable of this? I know a few years ago I was unable to find anything, but thought maybe some new options have emerged...
 
I suppose it's how big the item in question you're looking to cast is. I cast some small things in clear polyester resin quite a bit with the Castin' Crafts junk from the hobby store and I get fairly good results with it. Granted, I have to work in fairly warm conditions, use more hardener than it's recommended, and then post-cure every piece but it gets the job done. I can't imagine doing anything large with it though.

Smooth-On has some I want to try out but I can't buy it online and I can't bring myself to drive three hours to the nearest supplier for it.:wacko
 
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This is a cheap polyester resin. I did this pour back in 2006 when I could not get my then degassing chamber to work.

It is possible to mix and pour clear virtually bubble free but the results are very hit and miss. This part still has 6 bubbles. And this was done breaking all the rules. I let the resin stand so that it had no bubbles. I then slowly added the cat. I used a wooden stiring stick and never took it off the bottom of the pot. Once all the swirls were gone, I tipped it into the mold so it ran down the side. The mold in case was the foil wrapper of a big M&M.

I was attempting to make solid resin prisms back then and out 20 poured, just one came out bubble free.

So if you don't have a pressure pot, you really want to get a degassing system.
You still have to learn how to pour as you can still trap air and make bubbles.

You can find a complete 1 gallon degas kit on eBay. These are good little kits.

Sent from my SM-G900I using Tapatalk
 
I tried for a while to cast clear resin without a degassing chamber and I soon came to the conclusion that is is near impossible to get consistent casts without one. There are a few ways to cheat it, but the results are rarely repeatable.
 
Thanks all for the input - the item I want to cast isn't very big (about 6" on the longest dimension). I may be better off trying to find someone here who already has the capabilities, and send them a mold to just do it for me. While I would like to invest in a degassing kit, I can't imagine spending the money (plus casting materials) just for this one item.
 
Hecubus114 said:
If I want to cast something in clear resin, have no air bubbles, and safely in my own garage without a pressure pot, am I living in a dream? Is there any such product nowadays capable of this? I know a few years ago I was unable to find anything, but thought maybe some new options have emerged...
Click to expand...

Actually, you might get away with epoxy if you can do the pour in stages. Epoxy (there is now a UV stable version that stays water clear, as the older stuff goes yellow quite fast) has a long pot life like 35min + at 25 degrees C. It can take anywhere up to 6 hours to cure, but most bubble will raise to the top if the pour is not too thick, and you run over the pour with a heat gun.
 
If you pretend you are working with someone sleeping next to you and dont want to wake him up, meaning you will do everything very slowly and gently, you might reduce the amount of bubbles. From my experience you can get a "pretty good" finish if you are careful but I'm looking to get a pressure pot as well because I'm never able to get like zero bubbles.
 
I've used both polyester and epoxy resins to good effect. Bubble free castings with the polyester, though it has a 24 hour cure time. The super long cure time is part of what helps as it gives the air time to rise to the surface. And of course being polyester there's some shrinkage.
 
bookface said:
I've used both polyester and epoxy resins to good effect. Bubble free castings with the polyester, though it has a 24 hour cure time. The super long cure time is part of what helps as it gives the air time to rise to the surface. And of course being polyester there's some shrinkage.
Click to expand...

24 hour cure time? What stuff is that? The longest I have heard of 8 hours at 25 degrees C. If the ambient temp is cooler, it will take longer.
 
It's a polyester. I've also used the clear epoxy but I'm never happy with the results with it. There's yet to be a clear resin that's been made that's ticked all the boxes for me.
 
PoopaPapaPalps said:
For me, it means popping it into a small toaster oven at 200F for 6-8 hours after the initial cure.;) It helps this hobby-crafts resin cure to a hard glass-like finish but too long and it'll become brittle.
Click to expand...

Ah jeeze. That sort of finicky timing doesn't seem worth it. Have you tried sun-baking? Only slightly relevant: I've bought some polypropylene boxes that smelled really strong of silicone (not exactly sure why). Leaving them out in the sun for 2 to 3 days bakes the smell away. My hope is that clear resin might get some use out of the sun too.
 
I just got my first vacuum chamber. Probably one of the smallest ones out there for around $60. The single stage vacuum pump cost even less than that. A set up like this would work well for your small project. And If you ever plan to do any other casting projects in the future I highly recommend investing in this set up. I tried casting my kyber crystals without, and even though I took thorough care not to create bubbles when mixing and pouring, a few still developed during the cure stage. If you are looking for absolutely no bubbles, a vacuum chamber is a must. If you don't mind a few small bubbles then it can be done with careful mixing. Pour your A & B first and let them sit for 1hr before mixing. You'd be surprised how many bubbles will rise to the top. Once there are no visible bubbles in either parts A or B, carefully pour them together and slowly mix with a non porous plastic stir stick with no textured surfaces. Starbucks drink stoppers work well. Do not use a wooden popsicle stick or anything else wooden. Use a resin with a pot life of at least 9 minutes. Good luck with your project.
 
Good to see others doing this.

I still want a pressure pot as well. There is a rigid polyurethane I used (not cheap stuff either) and it basically formed bubbled over night (atmospheric pressure dropped?) even though I had degassed the stuff for several minutes prior to pouring. I also found another forum member had experienced the same issues when casting in this stuff. he claimed that they did use a pressure pot, but based on the size of the bubbles in the top of his parts, I'd say the pot lost pressure before the product had cured.
 
I just checked the site where I got my clear resin from and unfortunately it looks like they don't stock it anymore. It was about 5 years ago that I used it so it's possible it's no longer made.

If using epoxy you can add methylated spirits (denatured alcohol in the US, I think it's called) which will thin down the resin and slow down the cure time. This might help to prevent bubbles from forming in the first place, though I don't know how it would affect the clearness of the resin.
 
PoopaPapaPalps said:
It's a polyester. I've also used the clear epoxy but I'm never happy with the results with it. There's yet to be a clear resin that's been made that's ticked all the boxes for me.
Click to expand...

OK. Did you only mix say 1.5% CAT instead of the 2 or 3%. I've done this myself and it takes forever to go off. However I also did this because I was degassing and didn't want the heat from the degas process (water boils at room temp under vacuum) to kick off the resin.

- - - Updated - - -

bookface said:
I just checked the site where I got my clear resin from and unfortunately it looks like they don't stock it anymore. It was about 5 years ago that I used it so it's possible it's no longer made.

If using epoxy you can add methylated spirits (denatured alcohol in the US, I think it's called) which will thin down the resin and slow down the cure time. This might help to prevent bubbles from forming in the first place, though I don't know how it would affect the clearness of the resin.
Click to expand...

Actually that other expensive polyurethane I mentioned above dissolves in metho. I found that out by mistake, but not a bad thing as methos is way cheaper than acetone for clean up.
 
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