To prime or not to prime

[MF]

being doing a reparation on the sides of my old boat, a sea cobb - Italian shipyard Tullio Abbate, so i was considering gelcoat instead of two layers of international 880 and final paint...

[glassdave]

Originally Posted by MF

Hi, i take the opportunity to ask a few questions to the glass guru !
Never sprayed gelcoat before, is it a lot harder ti spray than awl grip or poliurethanes paints ?
What are the stages for painting with gelcoat and do you need a stronger compressor to do the job ??

actually in some senses its easier. Yes you will need a good compressor to spray gel. Using an automotive type gun you will need a big tip to, i use a 2.2 on my GTI gun and it seems to work pretty good. With paint the prep work before spraying is critical and the time consuming part with gel its the opposite. All the time consuming work is done after it cures, sanding fairing and buffing.

general steps for gel are:

sand and fair out all surfaces to about 180. Do any filling at this stage and also finish to 180. If you are confident in you ability to make things straight your ready for gel.

Mix gel and Duratec at about 30 to 50 %. Instructions call for 100% but I've never seen the need to go that much, cant imagine it would cover to good. At any rate the more Duratec you but in the more it flows out and I've found the best compromise to be in the 30-50% range. Catalyze the total volume at 2% and shoot a tack coat (dust coat) and allow that to flash for a few minutes then put on continous even wet coats until the desired film thickness.

Let cure till next day and your ready to tune up the surface. I break the gel usually pretty course like 180 again to get the initial straightening off to a good start then step up grits quickly 180-220-400-600-800 so on. Be careful of any edges as it may be possible to go through easily. I usually do the courser grits by hand up to 400 then move to a DA for the fine stuff, again be careful. I have found stepping to 1000 on a DA then 3000 Trizak wet makes buffing effortless but its very hard on expensive sandpaper.



A variation on this is to spray the gel with only a wax additive to get max fill properties and block that down in 180 and recoat with a heavily thinned (50-100% Duratec) gel for maximum flow. Will flow alot like paint and make follow up gloss building easier but this requires spraying the boat twice.

[racinfever]

Sometimes when spraying gel with just wax additive i end up with a sticky surface, do i need more or less wax ?

[persuaderboats]

Originally Posted by glassdave

actually in some senses its easier. Yes you will need a good compressor to spray gel. Using an automotive type gun you will need a big tip to, i use a 2.2 on my GTI gun and it seems to work pretty good. With paint the prep work before spraying is critical and the time consuming part with gel its the opposite. All the time consuming work is done after it cures, sanding fairing and buffing.

general steps for gel are:

sand and fair out all surfaces to about 180. Do any filling at this stage and also finish to 180. If you are confident in you ability to make things straight your ready for gel.

Mix gel and Duratec at about 30 to 50 %. Instructions call for 100% but I've never seen the need to go that much, cant imagine it would cover to good. At any rate the more Duratec you but in the more it flows out and I've found the best compromise to be in the 30-50% range. Catalyze the total volume at 2% and shoot a tack coat (dust coat) and allow that to flash for a few minutes then put on continous even wet coats until the desired film thickness.

Let cure till next day and your ready to tune up the surface. I break the gel usually pretty course like 180 again to get the initial straightening off to a good start then step up grits quickly 180-220-400-600-800 so on. Be careful of any edges as it may be possible to go through easily. I usually do the courser grits by hand up to 400 then move to a DA for the fine stuff, again be careful. I have found stepping to 1000 on a DA then 3000 Trizak wet makes buffing effortless but its very hard on expensive sandpaper.



A variation on this is to spray the gel with only a wax additive to get max fill properties and block that down in 180 and recoat with a heavily thinned (50-100% Duratec) gel for maximum flow. Will flow alot like paint and make follow up gloss building easier but this requires spraying the boat twice.

I still think gel is easyier to work with than any other paint. Some painters just can't deal with it, I just tell them quit thinking like a painter, gel is really just pigmented resin that you spray on.

In a pinch, I've brushed it on in places, and after sanding you couldn't tell.

[travisluman]

Thanks Dave. Let me know if you find those pics. I'm out on the West coast and have never come across a hull like mine although I realize it is quite popular on the East back in the day.

[glassdave]

Originally Posted by racinfever

Sometimes when spraying gel with just wax additive i end up with a sticky surface, do i need more or less wax ?

How much are you putting in now. I would guess more, to much just makes the surface very dull.

[MF]

Thanks for the advice, i'll give it a try.
Btw, How's the cig 20 resto coming ?