Author Topic: Question: High Strength Gypsum or Resin?  (Read 1984 times)

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Ztrains

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Question: High Strength Gypsum or Resin?
« on: April 18, 2009, 03:14:34 AM »
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Hi,

I'd like to ask a question regarding Z accessories and the choice of material made to produce them. I've previously made, and offered for sale, a few accessories such as abutments and portals. I've always cast these pieces in high strength gypsum. I'm now considering using resin as my casting medium and would like any opinions on both materials.

I've preferred gypsum in the past as I've felt it gave the pieces a nice bit of tooth for paint and weathering as well as for the feel of stone.

Pressure casting resin does offer some interesting qualities too however. I find once a fine coat of primer is applied, there is the tooth for the following application of paint and weathering. In addition of course... resin pieces are more durable.

Do you typically prefer one medium of another, and as a general rule, do you expect a piece cast in one medium to cost more than the other?

I'd appreciate any opinions on this.

Thanks
John
www.ztrains.com

John

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Re: Question: High Strength Gypsum or Resin?
« Reply #1 on: April 18, 2009, 07:28:33 AM »
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I personally like cast plaster for things like retaining walls, abutments, etc .. I like resin for the detail model things

sparky

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Re: Question: High Strength Gypsum or Resin?
« Reply #2 on: April 18, 2009, 11:26:36 AM »
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I agree with John.  I prefer to stain rather than paint rock or stone, and plaster is a perfect medium for that.

GaryHinshaw

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Re: Question: High Strength Gypsum or Resin?
« Reply #3 on: April 18, 2009, 02:44:38 PM »
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While not a Z scaler, I prefer the strength of resin and feel it can be finished reasonably well.  But I have found resin to be a *&^%$ to cut in cases where I've wanted to mod a piece (which is quite often).  Maybe this is less of a problem in Z with smaller parts, and maybe there are better cutting techniques than a razor saw. Just a caveat.

Ztrains

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Re: Question: High Strength Gypsum or Resin?
« Reply #4 on: April 18, 2009, 04:30:11 PM »
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One small point I should have mentioned. I give all my gypsum castings a coat of primer so paint rather than stain is almost a necessity. I do this because with my gypsum mix I use a dental surfactant in my mix and in my molds. This is done to eliminate all bubbles and it does a great job of it. The downside to this is the surfactant can cause uneven stain application so every piece gets a light primer.

On the resin pieces I pressure cast in order to capture detail and I find this works well. Of course as mentioned... resin is almost impossible (almost) to modify.

I'm almost thinking I may have to use both materials, gypsum and resin, for different pieces. I did attempt casting the shed (below) in gypsum and it does work... but surviving through the mail intact is iffy.

Gypsum bridge:


Resin shed:


John
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sparky

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Re: Question: High Strength Gypsum or Resin?
« Reply #5 on: April 19, 2009, 08:21:15 AM »
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I have to say, the resin shed looks as good as anything I've done with plaster.  Care to share the details on the finishing techniques?

Ztrains

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Re: Question: High Strength Gypsum or Resin?
« Reply #6 on: April 19, 2009, 04:46:27 PM »
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Hi,

Thanks on the compliment. The white resin shed was washed then given a coat of automotive adhesion promoter. A light coat of white primer then alternating coats of weathering powders and the adhesion promoter to lock to powder in. I like the adhesion promoter as it holds really well and dries almost immediately. I also use this for the ties on my flex track prior to paint and weathering.

John
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3rdrail

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Re: Question: High Strength Gypsum or Resin?
« Reply #7 on: April 19, 2009, 05:05:03 PM »
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Automotive Adhesion Promoter?? Tell us more about this stuff! Sounds like what might be needed to put light weathering powders on things.

Ztrains

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Re: Question: High Strength Gypsum or Resin?
« Reply #8 on: April 19, 2009, 05:53:32 PM »
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Automotive Adhesion Promoter?? Tell us more about this stuff! Sounds like what might be needed to put light weathering powders on things.

This is exactly what I use it for:

http://www.duplicolor.com/products/adhesion.html

I use the Duplicolor brand as it's stocked in the auto parts stores near me. It in many ways appears to work like Dull Cote but I feel it grips on "slippery" plastics a bit better. It also gives a very good tooth for powders. As I mentioned it dries very quickly and flat and it goes on nice and thin... another plus so you don't end up covering much detail.

John
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