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Casting Resins

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  • Member since
    January, 2016
Casting Resins
Posted by Liquid Magma on Thursday, April 07, 2016 11:10 PM

I'm curious if anyone knows what materials the aftermarket companies use for resin casting. I've used the standard Alumilite but the short pot life can be annoying, especially for complex parts. Haven't tried the "slow set" with a still fast pot life of 7 minutes. Time to work out bubbles has been my biggest issue. I know you can use vaccum chambers and pressure chambers to reduce bubbles in the resin, but that takes more time too and more expensive hardware to buy.

Most aftermarket parts these days seem to come in a gray color resin. Is this a different resin system or just died for coloring? Any idea what processes they use to get such nice looking castings?

  • Member since
    November, 2009
  • From: Twin Cities of Minnesota
Posted by Don Stauffer on Friday, April 08, 2016 9:24 AM

Yeah, the short pot life doesn't make things easy.  Micro Mark has a couple of options on speed of the casting resins they sell.  I get most of my resin and RTV from them.

Don Stauffer in Minnesota

  • Member since
    September, 2009
Posted by Cobra 427 on Monday, April 11, 2016 5:38 PM

Try www.specialtyresin.com this is where I get my resin from. Theirs allows you more time to pour your resin, and work with it. I use www.uscomposites.com for their silicone rubber. There aren't too many things that are required to cast good copies of parts. I've made my own X-wing fighter in 1/48th scale with their resin. I need to finish making the rest of the parts before I can release it as a kit. Before that I need to make multiples to finish the wings. Then I'll post that here on this website. You can also go to www.smooth-on.com but be warned that their prices are expensive as you'll have to buy quite a bit of resin - maybe more than what you'll need. Which is why most people who buy from them do so when making a "garage kit" so that they can get their moneys' worth out of it. Either way, this should give you more options to work with than just using one product that isn't satisfying! 

 As far as colouring - you can get dyes to add to your resin for either an effect, or to match parts that you're copying, or to add your own tint for identification - to set them apart from other garage kitters' parts. As far as pressure pots I don't use them and I get perfect results without bubbles, or deformation. You'll want to wait the full fifteen minutes after the resin has cured enough to be removed from the mould otherwise you'll get what is known as "soft pulls" that will deform the part before the plastic can cool. You'll want to make single moulds so that you can remove the rubber from the mould box once it's cured so that once you decide to use resin with it that you can squeeze the air from the mould while the resin is still liquid. Most resins are clear when you first mix them. This is so that you can see bubbles in one part moulds, and remove the bubbles before the part(s)cure up. Some people use corn starch to make the mould less sticky to allow the surface tension of the resin to spread out more evenly. However, this can stick to the surface of the resin, and give undesireable results. You can also use silicone release agent to make the mould last longer, but my good friend Scott (Captain Cardboard) says not to use this as it has never done any good for anything he's ever made. I agree with this too, and the silicone rubber isn't affected at all when simply stored properly. The rubber I use is sufficient to make parts without using a pressure, or having to degas it before doing so.

Put into a drawer after wrapping in plastic wrap will keep (moulds) fresh, and prolong their shelf life - what the manufacturers call "library life". You can keep them longer if you decide that you want to use them for a later use, and not have to worry about stickiness, or becoming hard over time. Keep in mind that when you pour resin into small moulds that it will resist going into every part of them as the surface tension is affected by the viscosity, or thickness of their formulation. Look to see what the Viscosity of the resin is. The centipoids - NOT centipedes is the CPS rating you should see on most resin sites. Use this to determine how thick, or thin you'll need your resin to be so that it will conform to the smallest of places in your mould(s). The higher the number the more viscous, or thicker it is. The lower the number the thinner it is. You want thin to get into tiny crevises, and for crisp detail without voids, or "shorts" in the cast part. Another thing to consider is to ensure that when you remove your resin that you remove all of it from the mould (once cured) so that there are no small pieces that sometimes fall off in it to interfere with future casting. I hope that this helps. If you need more help, just ask. 

~ Cobra Chris 

Maybe a picture of a squirrel playing a harmonica will make you feel better?

 

 

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