Old plaster molds

[Disbanded Designs]

Good morning everyone,

I recently got my hand on some old plaster molds for a really good price, as I'm going through them I'm noticing some of them are not in great shape.  I was wondering if anyone had any experience with re-creating plaster molds?

 

My initial thought was to make a silicone "mother" that I could recast in Plaster to make a new mold.  Just wondering how people have done this and any tips are much appreciated.

[Chilly]

If you use plaster to cast from these moulds, you will then be able to re-carve the poor areas. 

And then use them to make new moulds.

[PeterH]

Video of making a flexible block mold:

... also see the comments on its web page  https://tinyurl.com/2nceucyy

A short thread discussing the best flexible compound to use.

Of course the old-time industrial  mold makers -- who didn't have the materials we do -- made plaster block molds, often requiring multiple parts. Probably cheaper, but more labour and skill intensive (and easier to damage).

[Jeff Longtin]

To answer your question: yes I have done this. First I cast a clay piece to see what the casting actually looked like. After I decided that the parting lines were pretty good I then sealed the mold and poured a plaster reproduction. THEN I cleaned up this form and began remaking the mold.

The molds in question were made by an artist who attended the original Bernard Leach/Shoji Hamada workshop held in Minneapolis/St Paul in the 50's. I was honored to be  involved in the project.  (His widow had no use for the molds, once clay pieces were made, so she just discarded them. Such is life.)