Cold casting shape with least finishing

[Mark Pearce 1Participant @markpearce1]

I want to cast some barrels for a friend (1 inch diameter, couple of inches high), I'm in two minds though.

I made a one piece mould and it seemed easy, but achieving a perfectly flat base is driving me mad.

I've tried resting a heavy, flat object on top of the polyurethane resin as it sets, which seems reasonably successful, but it's still a fiddly job when there's so many to make, and sometimes creates awful airbubbles- just wondering if there's an easier way?

One idea I had was to make a base sepeeratley and insert that into the end of the one piece mould as it cures- unsure if that would work??I thought maybe a two piece mould might be more successful, but I'm not sure, i'll end up with a sprue to irritate me instead!

Thanks for any help at all,

Mark.

[Mark Pearce 1Participant @markpearce1]

[JasonBModerator @jasonb]

Cast the item upside down and have a riser, when set saw off the riser and sand the base flat. That is the way model figures are usually cast and the maker than has to prep the mating surfaces.

[Mark Pearce 1Participant @markpearce1]

Thank you for the kind reply. Great information. Do you think I could also make flat things this way(like a coin or disc-6mm thick)-if so would I have the piece parallel or perpendicular to the riser?

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