Help support TMP

"Making one sided silicone molds (hirst arts type)" Topic

12 Posts

All members in good standing are free to post here. Opinions expressed here are solely those of the posters, and have not been cleared with nor are they endorsed by The Miniatures Page.

For more information, see the TMP FAQ.

Back to the Moldmaking and Casting Message Board

1,017 hits since 4 Dec 2015
©1994-2018 Bill Armintrout
Comments or corrections?

Petrov Inactive Member04 Dec 2015 9:15 a.m. PST

Hey guys I was wondering how hard would it be to make those flat molds in 10mm/N scale for terrain.
I want to make some panels for buildings that will have detail similar to this panel:

Was wondering if that was doable with a silicone mold?

Razor7804 Dec 2015 9:33 a.m. PST

Its really very simple. Attach the piece to mold "bottom side" down onto a base (I normally use foam board ) then build walls around it high enough for the silicone to cover the object sufficiently to make a good mold, then mix the silicone and pour it in and let sit overnight. I use a company called Smooth-On. Cant say enough good things about them and they have how to videos on their site

VCarter Supporting Member of TMP04 Dec 2015 9:34 a.m. PST

Very easy. Pick up an Alumilite molding kit from Hobby Lobby. Some of the starter packs include the mold making mix and the casting plastic.

I've done quite a bit with it. One project was to build a space ship door. Instead of attempting to build 40 more, I just built the one out of plastic, made a mold, and cast away.

Petrov Inactive Member04 Dec 2015 9:36 a.m. PST

Ok I know I am going to need a vacuum chamber, but should I brush on some of the mold material on with a brush first since the details are going to very fine?

dampfpanzerwagon Fezian04 Dec 2015 10:00 a.m. PST

A vacuum chamber would help, but for one sided moulds as you are proposing a vibration table would work. If all else fails place the mould on top of a washing machine or a tumble dryer (while switched on – obviously).

This is usually enough to get rid of most air bubbles.

Good luck.


Petrov Inactive Member04 Dec 2015 10:48 a.m. PST

I was talking about making the mold itself.

VCarter Supporting Member of TMP04 Dec 2015 11:48 a.m. PST

I've had very few problems making the mold with Alumilite. Pour slowly from the side and shake the mold a few times.

There are more issues (with bubbles) when you attempt the casting.

Xintao04 Dec 2015 2:40 p.m. PST

I've done it. Very easy. I made some custom Dwarven Forge River pieces.

Get a very flat surface. I use Cermanic tiles from Home Depot. You can buy single tiles for about $1. USD

Get some lego pieces to build a dam around your piece.

Use modeling clay to seal the joint where the lego and tile meet, both sides. The clay also holds the lego dam in place.

Use smooth on mold products. I use Smooth-On PMC 121/30 wet. ONLY because my local hobby store carries it. I think there are better Smooth-On products than this.

Make your self a "bang board" as a manual vibrating table. Piece of wood and kitchen sponges that you bang while pouring.

Easy peasy.

Hirst Arts has pages of tutorials for newbs like me and you:


Zephyr104 Dec 2015 3:15 p.m. PST

"should I brush on some of the mold material on with a brush first since the details are going to very fine?"

By all means, yes. (I use a toothpick.) The object is to put on a thin coating and get rid of any air bubbles on & around the master before pouring the rest (the initial coat also acts as a barrier to air bubbles.) And, also use a mold release on the master.

Zagloba04 Dec 2015 9:52 p.m. PST

If you have a Reynolds Advanced Materials near you it is worth a visit:

I used OOMOO 30, stir well and pour from relatively high up to minimize bubbles.


HobbyDr05 Dec 2015 5:57 a.m. PST

I agree 100% with Zephyr1. Also, begin the pour in a corner, then draw your cup upward so you have the thinnest stream possible flowing into the mold. All of the large bubbles and most of the smaller will burst in the thin stream.

Good luck, it's a lot of fun.


Greylegion05 Dec 2015 7:52 p.m. PST


All of these folks are giving you good information and advise. You will not need the vacuum chamber. A little vibration goes a long way, during the casting process.

Sorry - only verified members can post on the forums.