Hi, my name is Ferg, from Ireland but living in Thailand, and I'm a complete rookie in the art world. I've been working as an architect for the last 15 years or so and now I'm trying to break out and do something more creative.
I was wondering if anyone could help me with a little art project I had in mind. I want to make plaster casts of some small manhole covers. I want to make them in plaster, so the first step is to take molds of the steel manhole covers out in the street, pavement whereever. the ideal material for this is a quick drying liquid (for working in the public street) which sets in minutes into a flexible rubbery mould( so the mould can be peeled off without tearing). normally its used for making dental moulds, but would be very expensive in this application. so I'm looking for an alternative, some kind of homemade paste? playdough? i tried acrylic latex sealer but it was far too sticky and slow drying.
any suggestions appreciated......thanks
Ferg

I know Sculpey makes a flexible clay mold, although if I remember correctly it needs to be oven-baked. I used it once several years ago. It would probably take quite a bit for a manhole cover, but I think it was reasonably priced.

If the relief is not to deep, you could use an oil based clay with a cheese cloth or burlap layer.

First dust the manhole with baby powder (or other fine powder) as a release agent. Then press the clay into the relief, next press the fabric into the clay. Smooth the clay that comes through the fabric, and add more clay. If you are careful, the clay will peel away without too much distortion. I have used this method to get shallow carving details from furniture.

Silicon would make a good mold that will have a rubbery and pliable texture it can also be cleaned and reused over and over again. The only downside is that it may be more costly approach for this project and I am not sure if it will require a catalyst to hold it together.