Question for you resin casters...

[indydog]

I have decided to try my hand at casting small parts. I intend to do small parts... ie wheels, tires, suspension parts, etc.

I bought a couple Alumilite casting kits and gave it a try. I used 1 kit for a 2-part mold and it worked fine. The other I used for a 1-part flat mold and that's what I'm having trouble with. I followed the instructions EXACTLY (it said "pour this into that and use it all) but it will not set up. After 3 days, it is still about the consistency of white glue.

My question is this.... I can pour out most of it, but how can I remove the uncured rubber from my master?

[baddad5]

I use this for casting small 1/64 parts, and much it's simpler for casting small items...very easy to use, inexpensive and readily available at hobby Lobby or other craft type stores.
Then I use Alumilite AlumiRes part A and B resin for my poured part...also available at same.
Using these products, I've found thru my tests, your mold is a lot more durable to make repeated molds, less prone to overall mold shrinkage. They are very forgiving and easy to use.




In answer to your question -at this point you'll have to pour out and hope it stays to its shape.. wait for it to fully cure and maybe you might be able to pull from it.  Did you use a mold release (talc or liquid)?  -is this a plug mold or one casting?

[indydog]

Yea, I used a mold release on both the part and the box. I guess I'll just let it sit and hope it cures.

[Calvin]

Low temperature can slow down the curing (under 50°)

I use alumilte rubber for cheap molds for one time pulls and it does have the tendency to cure slow (1 day) but I don't bother calculating the ratio properly, I just eyeball everything these days. 😂 lol

But it's absolutely beyond me why it's not curing for you?

Paper towels and alcohol is what I would do to clean off a master.

[smbrm]

As mentioned, ratio and temperature is important to how rubber and resin cures and how long it takes to cure. You can be wrong either way. If rubber is too hard it can be brittle and tear easily or too soft and will be too stretchy after curing. The rubber actually never stops curing and can become brittle in storage. If rubber is too stretchy parts without enough margin cannot hold their shape properly. But you also don’t need three decimal point accuracy for your measurements. Volume measure of rubber components, I have usually found ok. Counting eye dropper drops,( dedicated droppers for each component and cleaning after use) i have found to be accurate enough for resin. Both need to be mixed well and uniformly. Age of the components is also a factor, more so for resin. I have also used alcohol for cleaning off uncured rubber, but it is tedious to get it all off the master.

I have used alumnalite and smooth- on products. Taxidermists also have rubber and resin products.

[indydog]

Thanks guys. If it hasn't set up by this weekend, I'll dump it, clean the master and repour.

[Chris]

I have used Smooth-On very successfully, cast some Flat Head Ford engines and a bunch of wheels came out nice. I found the Smooth-On to be almost free of bubbles if mixed up correctly. The Smooth-On site had some helpful videos too. Chris