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View Full Version : Epoxy or Polyester Gel Coat with Epoxy Resin



colinph
20-Aug-12, 08:56 AM
Hello All, this is my first post in here. I am starting on my first build of a hovercraft at the moment. I am currently making a mould for the fibreglass hull. I am not working to any particular design plans, but am looking at some common dimensions based on pictures etc. Planning on a Briggs Vanguard engine and combined lift/thrust design with segmented skirt.

I have 5l tin of West Systems epoxy resin and hardener along with a good sized role of powder bonded copped strand mat. To keep costs down I will be using these but on east coast fibreglass site they dont appear to list an epoxy gel coat? I have read varying success of polyester gel coat bonding to epoxy so was looking for some advice from the experts :)

Also can anyone suggest a good read for helping me make sure I design the volumes of air required for lift, skirt design, etc please?

Any help much appreciated.

Colin Heath

Keith Oakley
20-Aug-12, 09:41 AM
Are you in the USA? Our colleagues in the US www.hoverclubofamerica.org (http://www.hoverclubofamerica.org) may have more info on resin suppliers over there.
Keith

colinph
20-Aug-12, 11:49 AM
Are you in the USA? Our colleagues in the US www.hoverclubofamerica.org (http://www.hoverclubofamerica.org) may have more info on resin suppliers over there.
Keith

Hi Keith,

I am in the UK. I can find the epoxy coats elsewhere but it made me curious why east coast didnt list as they seem to do everything else? Do people perhaps just wet up the mould with a coat of epoxy and let it set first then lay down glass and will this give a decent finish?

I am counting on maybe painting it anyway due to being first time on anything this large.

pest619
21-Aug-12, 11:29 PM
Most moulds are made from polyester resin and gelcoat since its a lot cheaper than epoxy ~4/kg compared with more like 15/kg. I have seen epoxy glass laid up over polyester gelcoat before but its not usual. If only using epoxy make sure you wax very well and probably use PVA release agent as well.

turnbu3656
22-Aug-12, 01:56 PM
I have recently used normal polyester brush gel coat with epoxy and had no problems. However we did have problems with spray polyester gel as it did not bond with the epoxy stsyem we were using and flaked of in large bits.
Previously we have used vinalester gel as it is compatable with epoxies and has a similar youngs modulous so should not delaminate due to flexing of the laminate. If using epoxy stright onto the mould then as Peter says, make sure the mould is very well polished, and I recomend using a PVA barier film to ensure it does not stick.

Good luck
Dan