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What resin to mould from ABS plastic?

Discussion in 'Tech Tips and Advice' started by graeme, Dec 11, 2015.

  1. graeme

    graeme New Member

    does polyester resin or gelcoat melt or soften abs plastic (actually it's acrylic capped abs, whatever that is?) as I need to make a mould from something made from this.
    If I use epoxy, can I then make a polyester item from the epoxy mould or are they incompatible
  2. Gary

    Gary Administrator Staff Member

    Hi Graeme, sorry for the late reply on this one...
    ABS is softened by polyester resins and it absorbs styrene quite rapidly but some resins are designed to bond to it - they
    have short gel-times and are usually used filled and either sprayed with a resin glass depositor or hand layed.
    Scott Bader make Crystic 990PA for this application .- its very low in viscosity and is designed to be filled with a high level of filler to reduce costs.
    Acrylic sheets can be made with a layer of ABS plastic bonded to it and this makes it stronger and less likely to get damaged when vacuum formed
    over heated moulds , its then called acrylic capped ABS.
  3. graeme

    graeme New Member

    Ah OK, so in fact the moulding will be taken from the acrylic part, rather than the ABS part. So really the question should have been what gelcoat to use on acrylic to make a mould and ensure it releases and doesn't damage the acrylic?
    Can i work in polyester or should i use epoxy based?
  4. Martin @ EC Tech

    Martin @ EC Tech Tech Staff Member

    HI Graeme, to get around this you can use PVA release agent. If you get the Blue gloss version you will be able to see where it is being applied. Once sufficient coats have been applied this will create a polyvinyl skin and prevent the styrene from the gelcoat attacking the acrylic. PVA release is best sprayed on to maintain a good glossy finish although it can be applied using a foam brush (jenny brush).
    you could make an epoxy mould however to use epoxy you would still need to use PVA release agent to ensure a good release so a polyester mould would be more economical. If you would like assistance as you go along with your project you can call me on 0191 497 5134 to discuss and we can advise you on each stage as you come to it. Also if you can e-mail pics of the project to sales@ecfibreglasssupplies.co.uk this will also help. Kind rgds Martin
  5. Alan Tolliday

    Alan Tolliday New Member

    High with reference to the above '
    'What resin to mould from ABS plastic?' i have what i think is an acyrlic boat hatch with a broken off corner and wish to make a GRP mould from.
    I would intend to do the usual layers of wax then coats of PVA, would you think that this is a viable thing to do, and if not can you suggest a way forward.
    Many thanks Alan
  6. Steph

    Steph Administrator Staff Member

    Hi Alan, the same standard mould materials would be used, we have mould making kits containing these materials and release agents. All you would need to add is a GRP tool pack. The only thing I would change is to put the PVA release agent on first ,several coats, and then lightly wax and lightly buff off the wax before applying the gel. https://www.ecfibreglasssupplies.co.uk/category/grp-mould-making-kits

    Kind rgds

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