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Discussion Starter · #1 ·
I feel like I've left Mr. Wood hanging, so I'm going to try and post a quick tutorial. There are better products than what I used, more experienced people that have used them, and better idea's than mine, but here goes...

I purchased an Alumilite starter kit from Hobby Lobby, About $45.00 with a 40% off coupon. After reading the instructions, I purchased a digital kitchen scale from Walmart to get the exact ratio for the 2-part latex mold. I mixed the product with tongue depressors in paper coffee cups I already had.

I had a "master" (the part you want to reproduce in resin) built, but thought it was too thin, which it was, so I glued a thin piece of hobby wood to the backside of the master, bringing the total thickness to about 3/16th. of an inch. I really don't think you could go much thinner with Alumilite, but I don't know.

Then, I built a high-tech box out of a 1x4 piece of lumber, and screwed paint sticks to it for the sides, making it both longer and deeper than the master. Then I brushed on 3 coats of shellac to keep the latex mold from sticking. Did the same with the master. After the shellac dried, I used two-sided clear tape from Michaels to secure the master to the bottom of the box, and used the clay included in the kit to seal the sides. You don't want the master floating to the top of the latex.

I poured the mold, then waited for the time the instructions stated before removing the sides of the box, and carefully removing the latex from the master. Came out great on the car-side, not so great on the roof, as there is an "undercut" on the roof.

My first resin pour led to the resin sticking to the latex mold. Had to purchase an Alumilite latex mold kit from Hobby Lobby and try again. This time I brushed on 3 coats of mold release on the latex before pouring the resin. It was too much, and left the resin car-side waxy looking with some of the detail blurred. The next pour, using the same mold, no mold release, gave me a perfect car-side. My experience told me to use no more than 2 coats of mold release. The undercuts on the roof were the biggest problem which I have yet to solve.

Some pics. of the process:

Table Rectangle Tableware


Wood Box Plywood Hardwood Coffin
 

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Thank you !!! This is very helpful. I have been wondering exactly what and how was involved in using resin like this. This is interesting and clear.
 

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Harry Henning III molds a lot of stuff using a Latex material painted in multiple coats on the master to make the mold. To mold the actual parts, he's using a 2-part epoxy in the rubber molds, the mold just peels off and is reused. I don't know if it could do the details that are in the car sides, but it works well for stuff like bridge sides, etc.
 

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Midland, Thank you! I assume if you bought the kit at Hobby Lobby it comes with directions which is great. My one question is:

I had a "master" (the part you want to reproduce in resin) built

That is my biggest concern. I seems the master would be something you construct or use a piece from another model to serve as the "master". I would be concerned about the art work in building my own Master.
 

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I have done some of this. Let me add a few points.
I have always made my containers using 1/16" styrene sheet. The club bought a 4'x8' sheet and we split it up. Its been a while but buying from a plastics distributor you can get it for a fraction of what a small sheet of Evergreen or Plastruct costs.
I have never had to use mold release with it.
I am using Smooth On products. They make a few dozen types of mold making compounds. Some you mix by weight, others by volume.
The ones you mix by weight tend to have better tear resistance. Better if you plan to mass produce something.
I mainly make castings for repairs or replacement parts.
I have a friend who does a lot of castings and uses ready made items like a freight car or building part (think DPM kits) as his master.
Not sure its cost effective though.
One thing to keep in mind if you want to try it is many of the compounds have a short shelf life. Smooth On Oomoo 30 is only good for a year unmixed. Line up your projects before jumping in.

Pete
 

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Discussion Starter · #10 ·
We're back from vacation, and I'm getting got up.

I'd like to Thank Norton for replying. He's more capable to answer these questions than myself.

I imagine it would be quite possible to reproduce a freight car using resin. I think the time and cost would really prohibit it, though. Even if you wanted to produce in quantity, it would be cheaper to purchase something already built. If you are wanting something that isn't produced, resin casting becomes a consideration. I only had to build one car-side (master), instead of trying to build multiple sides.

I'm considering building a Colorado Springs and Cripple Creek steam engine using a railking chassis. I'm thinking it might be easier to cast the parts as I go rather than build the whole engine from scratch. I would also like to make a smaller tender for the Williams 10 wheeler. Using resin, I would only have to build one side of it. The possibilities are almost endless.
 
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