Model Railroading > Alternative Source for Model Resin Casting?

I have utilized Micro Mark's resin and rubber mold set-up before and it worked great. But Micro Mark has had it on backorder from their supplier for some time now. What alternative sources are there for modelers?  Like I did before, I want to duplicate resin parts in rubber molds for some scratch-building projects. I have some material left over from the first kit, but it had limited shelf life.

Also, is there any risk of shipping the rubber and resin components this time of the year in cold weather?

The resin allows me to save time by duplicating scratch-built parts when assembly needs many duplicate parts or building more than one loco with similar features.

Victor A. Baird
http://www.erstwhilepublications.com
 

The Micro Mark stuff is simple repackaged Smooth On products.  

Smooth On is a good source, also check PolyTek in eastern PA. I use their soft urethane mold making compounds extensively, and occasionally their casting products as well. 

Hobby Lobby stocks Alumilite prouducts.

Vernon Sargent
Greencastle, IN

I have used the Alumalite stuff a bunch, but I liked the smooth on much better.  It is easier to get though, and one can use the Hobby Lobby coupon to get it.  

Sounds good but what I am concerned about is getting the right material for fine detail and a good finish to paint. Honestly, I wasn't a hundred percent happy with the material I got from Micro Mark as it was yellow, brittle and not as smooth as I would have liked. But it did provide fine detail.

I wonder if Micro Mark's issue with not being able to provide it for so long is the shelf life?

Victor Baird
http://www.erstwhilepublications.com

Color can be adjusted with dyes, which are available in concentrated form from all the major manufacturers.  I tend to cast everything in battleship gray, obtainable by mixing white with black.

Material properties (brittleness, warpage, etc) vary quite a bit from manufacturer to manufacturer, and from product to product.

Critical issues:  

Viscosity:  Do you have hyper-detailed molds that trap air readily?  If so (and if you don't have vacuum equipment) you may need a very low viscosity material.  Downside is that these tend to be a bit more brittle than others.

Cure time:  Urethane resins vary in how long they take to set up, from five minutes or so to over 30. Obviously, the faster ones allow higher production rates, but for most individual modelers, this isn't all that important.  And faster resins also require you to mix more quickly and to pour into the mold faster, increasing your chances of trapping air bubbles.  Faster resins, in my experience, also tend to warp more readily and to be a bit more brittle, and to be a bit more temperature sensitive.

There are also some issues with shrinkage during cure, but I'm not familiar with those because they don't affect my operation very much.  But if you're casting p[arts that have to fit together cleanly, look into it.

My experience with both Smooth on and PolyTek is that their sales people are very familiar with issues like this and are willing to work with individual customers.  Give them a call or drop an email and see what response you get.

As for weather., this is the bane of my existence, since most of my products are made of latex rubber which is highly freeze sensitive.  I can't order latex between December 1 and the end of March in most years.  But for urethane work, I routinely order from PolyTek in the middle of the winter, and have had no problems.  There is no water in a urethane mix--if there were, all hell would break loose with the chemistry.

BTW, I think I heard somewhere that Alumilite and Smooth-On are now under common ownership.  Not sure of that, though.

Gardiner Cross
Cripplebush Valley Models



Edited 1 time(s). Last edit at 11/27/20 19:09 by march_hare.

Thanks for all of your comments and information folks, particularly Gardiner. Since the material comes in a smaller quantity, I may try some samples from my local Hobby Lobby and see if it serves my purposes.

Victor

Victor A. Baird
http://www.erstwhiepublications.com



Edited 2 time(s). Last edit at 11/28/20 18:32 by wabash2800.