Help with a 2 part Silicone Mold + Resin Casting

JoblessPunk

JoblessPunk

Well-Known Member
Hello!
This is not exactly a prop, but this is the best place I could think of to get help with this. Feel free to move/delete this if it does not comply.

I'm casting these parts:
photosy.jpg


I need them white.

I have made a 2 part silicone mold:
18851_259691608370_744203370_3558935_5965592_n.jpg


I'm using EasyCast Clear Casting Epoxy:
3527773w


And I'm using TAP Super Pigment White to color it:
156-super_pig.jpg


I have gotten two beautiful castings out of this mold I've made, but they are never "rock hard." Take in account I've only done two castings so far but here is my second casing:
photouq.jpg


The problem I think I'm having is that the parts are really small and the square one is pretty thin. My first casting I just left it room temperature and that one came out sticky/bendable. My second casting I made a "hot box" with a portable heater and kept the silicone mold/casting warm for about 36 hours. The casting wasn't sticky, and was harder than before, but still not "rock hard."

I have started my 3rd attempt and I'm planing on keeping the silicone mold in the "hot box" for 24 hours, then 24 hours of the silicone mold room temperature then take it apart.

Please if anyone can help that would be great. I'm very new to this and this is literally my first time doing any of this.
 
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I have never had any luck with easy cast. It never hardens for me. I've tried changing up the ratio's a little but no luck. I would just stick with a regular casting resin. A lot of hobby shops carry them now or you can order on line. Smooth-on is pretty good and I'm sure there will be some other suggestions.
 
Hi there,
I've have over 30 years experience in casting , in all media and can tell you it's the pigment that causing you the problem, but first a question - why are you using a clear cast resin? unless you want the part to be transparent or allow light to pass through it , use a proper two part thixotropic ( ABS ) style casting resin you'll find you will get much better results, most come in a basic white or cream colour, and your parts will not turn out like toffee - if you do want them transparent then use much less pigment and make sure it's completely suitable for use with the type of resin you're using as some are in compatible !! and once cast put them in a warm place ( like an airing cuboard ) for at least 48 hours before you de-mold and use a little unperfumed talc to stop them sticking. Wash and dry before use and use a good primer if painting.
 
I was going to say the same thing.The pigment may be inhibiting the resin,or if you are getting your mix ratios wrong of the parts A&B epoxy,other than that...good advice above.
 
Thanks for the replies,
I'm very new to this so I went into TAP Plastics and these are the supplies they gave me.

I want the part I'm making white-white, not a cream, does the ABS casting resin come in that? Does anyone have links to specific brands/products I should buy? Also, do I need a vacuum chamber? I don't have one and I'm really not looking to buy one.

Lastly, does anyone have "step-by-step" instructions on how to use ABS casting resin?

Thanks again!

UPDATE:

Do you think this product would work well for what I'm doing?
Has anyone used it before?
Alumilite White:
http://www.alumilite.com/ProdDetail.cfm?Category=Casting%20Resins&Name=Alumilite%20White

http://www.youtube.com/watch?v=T3uGvIu9czk
 
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No,the TAP Plastics urethane resin is not a "cream colored" resin,more tan.You may be able to change that with some white pigment,but you want to be careful about how much you put it,there is a limit.Too much can really ****** the cure if not inhibit the cure and the resin its;ef as you have discovered.You don't want to use polyester casting resins,they *SHRINK* like hell,are toxic and smell really bad.

The TAP urethane is a very good resin,if other resins you are interested in(and there are a number or other urethane casting resins),try Douglas&Sturgess Art Supply.They are Bay Area/local and have heaps of supplies.I believe they are still around/in business and they have to my recollection a wide variety of casting resins,but really get a thorough understanding of them.

Not all urethane resins are created equal and there is a trade off with each different kind.Some cure with a texture like ABS plastic, some are a very dark brown/tan color,some are off white to replicate a teflon or delren type plasit.Some cure very,very fast(short pot life),some off gass and leave an oily residue on the outside of the part,others are similar,have moderate cure times,have a tan to off white colors.Lots to choose from,so "pick your poison" carefully for what it is you want to do.
 
thanks again for the links and info,
I'm going to shop around and see what I can find. I want to say away from adding pigment to the resin because it sounds like that is what is messing up my castings. So, JPolacchi I think I'm going to say way from TAP Plastics tan resin and go with either Smooth-Cast 300, Alumilite White, or any other Pure White resin that is suggested.

One question,
How do I know if the resin is ABS, Polyurethane, Polyester, etc.?
It never seems like they Clearly state what it is made out of...

thanks!
 
How much pigment are you putting it? Are you weighing your amounts or doing it by volume? I've found that if I start going over 3%, it can "soften" (i.e. interfere with it crosslinking) the resin. Also, is the pigment compatible with the resin you're using? Some pigments are universal, some only good for a specific system (urethane or epoxy).
 
Mostly Fantasy said:
How much pigment are you putting it? Are you weighing your amounts or doing it by volume? I've found that if I start going over 3%, it can "soften" (i.e. interfere with it crosslinking) the resin. Also, is the pigment compatible with the resin you're using? Some pigments are universal, some only good for a specific system (urethane or epoxy).
Click to expand...

I'm putting a very small amount in, but since I'm only mixing a small amount of resin so I think the margin for error is higher.

ZOMBIEREPELLENT said:
I've used that resin before, about 7 months ago I cast a part for a model I was working on. It's still flexible
Click to expand...

Witch resin?
EasyCast Clear Casting Epoxy?
 
JoblessPunk said:
One question,
How do I know if the resin is ABS, Polyurethane, Polyester, etc.?
It never seems like they Clearly state what it is made out of...

thanks!
Click to expand...

You should be able to get the material saftey data sheet (MSDS) on line before buying.

I posted the link, but if you went to the main page, you would find the material under Urethane Liquid Plastic Resin.
 
Pzak said:
You should be able to get the material saftey data sheet (MSDS) on line before buying.

I posted the link, but if you went to the main page, you would find the material under Urethane Liquid Plastic Resin.
Click to expand...

Awesome, thanks. Since it is a Urethane Resin do I need mold release for my silicone mold?
 
foxbatkllr said:
No, you do not need a mold release. Mold release can help extend the life of your silicone but its not necessary.
Click to expand...

Sweet, thanks.
I'm going to buy "Smooth-Cast® 300 Series Bright White Liquid Plastic" when I get home later tonight. Thank you everyone for your help, I'll post my results once I get the resin.
 
thank you for your help every one!

photo3wp.jpg


I used "Smooth-Cast® 300 Series Bright White Liquid Plastic" and they came out perfect! The first one I did has a little marbling effect of clear/white, but I only needed two of these parts casted.

Thank you again for helping me find the resin I needed :)
 
Good to see you got the issue worked out. With Smooth-On, if you get a "marble" effect, that's just letting you know it's not mixed all the way. When they say scrape the bottom and walls of the mixing area, they mean it LoL
 
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