Latex Mold Builder Review

[FJ and G]

My limited experience with mold builder latex product sold at Michaels.

http://www.michaels.com/art/online/displayProductPage?productNum=gc0514

This latex product’s strength is its flexibility. When what you are casting is an odd shape, the flexibility helps to get the part you are casting out of the mold. Also, you don’t need to mix parts, as it’s ready to use out of the container. It smells like ammonia, even when used outside.

I tried casting a number of things from wheels to other railroad parts. The main difficulty in doing this is sagging. Thus, I’ve really only had good success with rock molds, although the product claims it can be used for other objects (I’d be interested in hearing some successes and how it was done).

As to the advantage of its relatively low cost, that is offset by the large number of brush on layers that are usually required and the drying times needed. It may, in fact, be more cost effective to purchase a ready made commercial rock mold. It is recommended that medical gauze be used to fortify the mold.

After about a dozen latex brushings, I soaked gauze in the mold builder and slapped it upside the rock. After it dried, I added about a half dozen more brushings (the amount of time spent doing this, I could have delivered pizzas and earned enough to buy a commercial mold). The whole process took 3 days and the mold endured bright sunshine and driving rain.

When I peeled off the mold, I had slaking in the rock, which resulted in layers of rock peeling off and embedding in the latex. Some pieces came out OK but others pierced the mold. In our area, there’s mostly sedimentary rock. I’d advise casting igneous or metamorphic rock instead to prevent slaking.

For mold release, I used canola oil and for casting material I used vinyle concrete patching concrete mixed with some red and brown latex for coloring.

The process worked but is messy and time consuming. I think it better to purchase commercial rock molds or to get the right types of rocks for your layouts in the first place.

In the meanwhile, I have half a bottle of this stuff left. If someone can tell me what to do with it, I’d appreciate.

Here’s some pix:














This last photo is unrelated but shows a 30’ long bridge I tore up b/c I didn’t like it. I saved the uprights, however, as they look like industrial archaeology stuff.

[tangerine-jack]

I've had zero success with making my own molds with latex and gauze.  I always end up, hours later, with a useless mess on my hands.  You're right; it's more efficient to purchase a commercial mold to do the job unless you have a very unusual subject you wish to cast.  The problem is that in order for the mold to have any stability (gauze prevents tearing only), it must be very thick which would use up the entire jar of latex for just one mold.

 

Take the unused latex to mold some GI Joes and have a little cattleman war.....

[dwbeckett]

Try the Dump site near you. rock casting has been a large scale problem for years. you could try coultred stone used in construction. My plan.

[Anonymous]

I have done several molds, if you want to do rocks you can use a latex mold use several coats (10) then use a backing material (i use left over static cling sheets). If you need the mold to keep it's shape ( say bridge enbankment) you need to have a rigid mold and a mold form then use something like bondo and bondo resin mixed 50/50 after it starts to set pour another coat of just bondo over it and added fiberglass chunks and let it set (of course you should have vasleline or a mold release before you start).