In Need Resin Casting Advice

[Rahn420]

In working on my 1/350 TOS E, I had my doubts on how well I could detail the bridge as it is supplied in the kit.

I thought it would have been nice to have had it as (at least) a three piece ‘mini’ kit (two walls and a floor).

I did so experimenting that I think look hopeful, but I need some advice.


First I made a silicone mold of the original bridge part.







The resin I am using is old. It’s two years past its ‘use by’ date, but had never been opened. I went ahead and tried using it as this is only a test of ‘possibility’. You will notice a lot of bubbles from foaming.

I partially filled the mold to the upper floor level of the bridge. I then flat sanded what floor there was away, leaving only the walls. I reinserted the walls into the mold.



I had a aerosol can of a mold release (previously untried) that I sprayed over the mold and inserted resin parts.

I poured another layer of resin covering the upper floor level and just a thin layer over the lower level (sorry, no photo of this stage).

I removed the parts and flat sanded off the lower level and command island.

I reinserted the parts into the mold, sprayed the release and poured another layer of resin to fill the lower level and command island.

So, three layers total.



Here is where I need some advice regarding resin and a separator.


My walls separated without too much difficulty, but my two floor levels would not come apart.





Question 1: What is a suitable resin to resin separator?


I also want to cast the final parts in clear.

Question 2: What is a suitable clear casting resin?

Thanks for any advice that can be given.

 

[Rahn420]

Well, I did manage to get the two floor levels apart, but not without cracking the upper level and putting a 1 inch slice along one of my fingers. Ouch!



The roughness around the edges come from the bubbles revealed during flat sanding. They then transferred themselves when casting the next layer.

They do help key it all back together, though.

 

[Pro Mod]

I've used Vaseline (petroleum jelly) as a release between resin layers and it worked okay.
I'd recommend you try a sample first to check it works with your brand of resin.

 

[NormanF]

Do you really need to separate the floor into two layers? It does not look like that is worth the effort.

Also, do you need a clear casting of the parts? If so, I have been using EpoxACast 690 lately for some indicators I am making and it is working really well for me.
EpoxAcast® 690 Clear Casting Epoxy Resin Product Information

Two issues to be aware of though:
1. It is epoxy which is an adhesive so you really have to use mold release for it.
2. You have to measure out the parts by weight. And for the small amounts I am using a kitchen scale just does not cut it. I ended up getting a reloading scale that measures thousandths of a ounce. Amazon.com: Frankford Arsenal Reloading Scale: Sports & Outdoors

 

[Rahn420]

Separating the floors was a "while I'm at it" afterthought.

I thought with the lower floor being a different color than the upper, you could paint them separately then layer them back together giving a clean paint edge between colors. The stairs and railing would also be easier to paint.

When I say easier to paint, I mean with the aim of straight, sharp definition between colors as much as possible.

I know I don't have the hand to paint so small and be happy with it. Wavy edges, etc.

Having parts broken down, I think I could get where I want.

Overkill? Me?... probably. I am picky.

Making the parts was pretty easy. I just need to find the right material.

 

[Rahn420]

I tried Easy Cast epoxy.

It came out crystal clear with no bubbles.

The problem I had was that it did not cure rigid enough. Maybe my mixes have been off.

After 3 days of curing, with moderated pressure, the bridge walls would deform. It would not stand up to the handling during sanding.

I've tried a couple of times, but still not getting what I want.

I may try a clear urethane next.

 

[NormanF]

I had bad luck with the EasyCast too, that was part of the reason I switched to EpoxACast. And for small amounts you need a seriously sensitive scale.

Sent from my Etch A Sketch.