Cold/Hot flow Gelcoat !

Hi guy's I'd like to know if I had a compleat mould (top & bottom) seald closed could I just drop in a big blob of gelcoat and rotate the mould so the gelcoat spreads itself through out the mould.

Also what happens if you heat gelcoat before aplication ?

cheer's guy's
Buckie

 

Really not sure if it would work. Only one way to find out though.

If you heat the gel just keep in mind that for every ten dergees increase in temp your cure time will half.

 

I'm just thinking out loud really, just a lazy way of mass production. Once the gel had cured the entrance would be opened and allow access for the glassing to be done, a sort of all-in-one boat. with most of the work being done while in the mould. (you know get the small children from the local school to work 4 hours after school, inside the mould) LOL

Buckie

 

If it helps, we do make consoles for our RIBs in a rotatable mould. However we still can sit inside to gel coat as gel will not spread well - that is why it is called gel!!!

It does help however to rotate the mould during layup by hand to redue pooling of resin, however it is a very practised art since too much resin leads to the top lamiate falling off before it is set, and too little leads to dry spots.

Temperature is really critical to all GRP layup, as we find with our products they are completely unspreadable at 14 degree Centigrade, great at 17 deg but set too fast at 22 degrees.

Have a look at the website:
www.explorermarine.co.uk for pictures of what we make
Regards

Hugh Mattos
www.explorermarine.co.uk

 

Vey nice and interesting too.....If I go ahead it would be a 36' cruiser all-in-one, mainly to be water tight to withstand any type of weather, I'm also looking at a zink alloy mould to look at the possibility of a hot plastic outer rather than a gelcoat. I've looked at an Acrylic 10 mm sheet but can't get a sheet large enough, I'd have to make it myself. (you know like a glass reinforced bath) Its just the investment that's stopping me at the moment. I have enough to go a head and build GRP Boats but I wanted to do something different. I've searched all over to try nd find the name of the plastic thats used for the little red boats childrenn use in the bath as they are indistructable and would prove a great material to work with.

thanks for the info.....

Buckie

 

Remember also that the fumes from GRP layup are pretty noxious, so working in a closed mould will be very dangerous.
For 36 foot boats most of the industry are moving to Resin Transfer Moulding or RTM Light in two sided moulds or vacuum bags.

It is a much easier process to bond two halves, than to make a single piece integral boat.
Good luck

Hugh Mattos Chartered Engineer
www.explorermarine.co.uk

 

RTM Lite is pretty cool. Almost cheap enough to do at home.

 

how would you know how thick it is?, and i would think you need to keep it spinning till the gel-coat kicked off

 

Gel coat thickness is measured with a simple gel coat gauge - until the applicant is experienced enough to " know " how thick it is.
Gel is a thixotropic liquid, so spinning it to fast will result in all the gel being at the keel and cabin roof!
Have a read of IBI News, which regularly reviews manufacturing practice around the world and has never discussed rotary moulding. That is normally reserved for polypropelene kayaks and oil tanks and storage drums.

Good Luck

 

Buckie,

You mentioned earlier about acrylic, have you considered HDPE? It's weldable to any size sheet you need. Boulder Boat Works make their small boats that way.

 

yes i, we should know about a gauge, heh, what i meant was, how ya gonna stick ya arm in there while its spinning,and what kind of mark will the thickness gauge ( scraper lol) gonna leave. and if it was a half complicated part, wouldnt ya have to spin it in 2 directions or more to get it in the hard to reach areas evenly