spraying gel coat

drewpster

Commander
Joined
Oct 17, 2006
Messages
2,059
I was wondering about how difficult it would be to set up for spraying gelcoat. I have not heard bad things about problems spraying it. But like everything else, it depends on who you talk to. I have a small compressor, two spray guns (gravity fed HVLP and cup fed primer gun). I was considering the possibility of gelcoating the little tri-hull below. (link) I made an earlier repair to the outside of the hull using epoxy, would it need to be removed? Just how difficult is it to do and get a good finish?
 

Yacht Dr.

Vice Admiral
Joined
Feb 26, 2005
Messages
5,581
Re: spraying gel coat

Hello drewpster m8 :)

Gel is actually very simple .. and forgiving..

Get the cheapo HF Siphon gun.. largest tip you can find. flush with acetone 3 times..

Prep with 80-180 ..

** gel mix **

4 parts gel.. 1 part patch aid ( cook composits 970x-*** ) http://www.ccponline.com/products/products.html

reduce with if needed depending on the gel you get.

cat 10cc/qt.

I mix/spray out of a 1 qt bucket.. mix as I go. flushing gun with acetone every 2 qt. ( I dont use the cup with gun.. I put the gun tube right into the mixing cup holding with hand ). You can also put a 1/4 hose on the end of the tube .. put that in your cup ( hold cup above gun ) and you can use your gun like a pressure gun ( upside down if you needed to ).

1 tack and 4 wet coats - 5-6 if thinned out over 30%.

You can spray PVA over gel after tacking..If you thinned too much .

Use a magic marker and acetone to guide coat your orange peel.

DA with 320/400 depending on how it flowed out..then 600 dry DA. Rub/buff out with 3m heavy duty. finish with 3m imperial compound..

http://solutions.3m.com/wps/portal/...E3E02LECIE20S4K7_nid=5FR43SWD04be9NQK7NZ8TZgl

YD.
 

drewpster

Commander
Joined
Oct 17, 2006
Messages
2,059
Re: spraying gel coat

Is the epoxy products I already used going to be a problem, (watertite epoxy filler, epoxy resin to repair cut).
 

ondarvr

Supreme Mariner
Joined
Apr 6, 2005
Messages
11,527
Re: spraying gel coat

Do you want to gel coat it to learn how, or do think it will cost less and be easier than painting?

To re-gel coat the hull it would be best to flip it over, because sanding upside down is no fun and will take about 4x as long, but at least on the hull you're sanding large somewhat flat areas.

To do the deck it can be a nightmare to sand around all of the details and contours, so look forward to many hours of sanding and raw finger tips.

Cost wise, gel coat and paint (depending on the type of paint) may be about the same up front, but after you spray the paint you're about done, after you spray gel coat is when the real work and additional cost begins. Good sand paper is pricy and you'll go through a bunch sanding the gel coat and if you sand through, you need to respray that area.

For a rookie spraying gel coat can be very difficult, the main reason is that you don't have much time after you add the catalyst to get the entire batch sprayed. It may only be 15 minutes or less until it gels and even less time in the heat of the summer, so people tend to destroy their spray gun when it cures in the pot. With paint you have a very long pot life even with two part products.

Gel coat also needs more air (CFM and possibly pressure) when spraying than paint does, so if the compressor can't keep up it slows down the process causing more problems.

Respraying a small area isn't that difficult with gel coat, resparying an entire boat is a huge project.
 

ondarvr

Supreme Mariner
Joined
Apr 6, 2005
Messages
11,527
Re: spraying gel coat

The epoxy can be an issue, gel coat doesn't bond all that well to it, and if stressed or banged it can pop right off.
 

drewpster

Commander
Joined
Oct 17, 2006
Messages
2,059
Re: spraying gel coat

I am planning to paint the topside regardless if I gelcoat or paint the bottom. I was thinking about trying the gelcoat to learn how, as well as add some durability to the bottom. (i have a bunk trailer)
Flipping the boat is no problem, I intended to do that anyway to finish the bottom. I think the epoxy issue is going to be my sticking point though. I knew epoxy does not like poly and I do not want to re-do the work I have already done.
I am going to use two part paint on the bottom. (if I dont lose my mind and try gelcoat.) I may spray some gel on some smaller projects first, just to get feel for it.
My compressor is an issue too. It is a lay down single stage with only about a 20 gal tank. (20+ yrs old) It kicks on when filling tires! It worked itself to death when I blasted my trailer the first time. I cannot bring myself to get a stand up one until this one completely dies.
Thanks guys,
Drewp
Btw- I have an idea on how to get that woven roving to lay down on my stringers. Im thinking of coming up with a bagging technique. I just have to come up with a vac pump first. (shop vac maybe?)
 
Top