Molds and Plaster Castings

@SLK posted his results with using 3d printed parts to create molds and resin casts. That prompted me to post up my own results. I also used prints to make RTV molds and then those molds to cast plaster copies

The model is of a Coke Oven face in 1:48. It consists of two columns and a large and small arch. The base is a piece of Sintra (PVC foam board) .. everything is glued together with epoxy.


I made a mold box and epoxied the model to it ..


I used Smooth On's 'oomoo 25' RTV. The only thing I would do different would be to use a brush to make sure the RTV was pushed into every crevice. Just pouring on did get 'almost' into every detail. One of the plaster castings in in the lower left


Close up of the cast piece


This is a test-piece I used to experiment with coloring. Since the brick in a coke oven like this would have been hard used, grimy etc. .. I sprayed some AI (Alcohol India Ink ) wash on, let that dry and then dry-brushed some FolkArt Terra Cotta acrylic

Very impressive. Could I ask what brand of plaster you used or does that make a big difference?

Glenn

Plaster is something I picked up at Hobby Lobby . something called "Pottery Plaster - for use in ceramics" .. it's harder then plaster of paris at least. If I had a choice would use Hydro-Cal .. but that's a pain to get my hands on.

Thanks. This is something I'd really like to try but I have no specific reason to order a large model and then make a mold from it - in other words I can't justify the cost to satisfy my own curiosity

Glenn

Glenn,
This is one oven in a bank of 16 for my On30 module. In reality, there would have been hundreds.



The 'brick work' inserted through the face of the structure and starting to add Sculpy 'stone' facing.



Still early in the process



This was my first time to use RTV. Went pretty well I think. The various 'bits' were ordered prior to the jump in cost for FUD along with some others so it wasn't that bad.

Holy c**p that is one impressive project... and I can see why you'd want to mold them rather than have them all 3D printed !