need advice on paint, gelcoat, duratec

[ondarvr]

Re: need advice on paint, gelcoat, duratec

Depending on how much orange peel there is on the gel coat after you've sprayed it, you may end up sanding 10 or 15 mils off to get it smooth again. Plus its very common to sand through if its thinner and then you need re-spray some areas.

Also you typically need at least 10 mils left for it to hide the color of what's under it.

Did you read the hull extension thread yet? Its required before starting this project.

 

[SKIBUM1M]

Re: need advice on paint, gelcoat, duratec

I read it before but just went back and reread the gelcoat part. The thing is he stripped the old gelcoat off where I did not. The data sheet says if you have the gelcoat too thick (over 24 mils) it will crack and if it is too thin (under 12 mils) it will blister and wont cure properly. Does this refer to the new layers of gelcoat or to the combined old and new gelcoat?

 

[proshadetree]

Re: need advice on paint, gelcoat, duratec

Ive sprayed paint for years tried gell a few months ago.Its a brand new thing.Mine had load of flake in it but it didnt flow well with a 2.5 gun.I used duratec as it was labeled. 1/2 and 1/2.Try this on something before you do your whole boat.Im still going to do mine but I already know its going to be the biggest pain ever.

 

[ondarvr]

Re: need advice on paint, gelcoat, duratec

I read it before but just went back and reread the gelcoat part. The thing is he stripped the old gelcoat off where I did not. The data sheet says if you have the gelcoat too thick (over 24 mils) it will crack and if it is too thin (under 12 mils) it will blister and wont cure properly. Does this refer to the new layers of gelcoat or to the combined old and new gelcoat?

To the new layers.
On a re-spray you don't normally have a problem with this.... but you can...its just one of the possible issues with gel coat.

 

[SKIBUM1M]

Re: need advice on paint, gelcoat, duratec

In a search for patchaid a local marina suggested I use Styrene Monomer instead. Do you have any experience with this and would it be better to use? He said it was not as tempermental as patchaid when it comes to temperature.

 

[ondarvr]

Re: need advice on paint, gelcoat, duratec

Adding styrene will do one thing fairly well and that's reduce the viscosity, the down side is that it will discolor (turn yellow) in the sun, cause the gel coat to become more brittle and less water resistant. Not good things

Patchaid will do several things. It will have some styrene in it, but it will also have other monomers that aren't as affected by UV light. It will also use a base resin similar to the one used in the gel coat, only with no thixitrope to raise the visc like what's used in gel coat. It it will have extra promoters in it to help the gel coat cure in a thin film, It will also have wax in it so the surface will cure tack free.

Because it uses a good base resin it will have little effect on the water and UV resistance.

Can things like styrene and acetone be used....yes....they just have some possible nasty side affects if you over do it. Adding less than 3-5% may not be very noticeable, but doesn't help a great deal either.

 

[SKIBUM1M]

Re: need advice on paint, gelcoat, duratec

Ondarvr, you are the man when it comes to gelcoat. It is great to have your wealth of information available. Thank you so much for all your advice.

 

[lowkee]

Re: need advice on paint, gelcoat, duratec

This was an awesome read! I can't wait to see some posts on how you make out in your first few sprays, skibum. I'd love to gecoat the deck of my boat, but just haven't talked myself past the hurdles of gelcoat yet. I haven't seen a single photo in your resto thread in a while, skibum.. I've been jonesing! Seeing as you are in NY, I can understand the delays. It is warmer down here and I still have to drag my butt outside to do anything.

 

[SKIBUM1M]

Re: need advice on paint, gelcoat, duratec

Dont worry lowkee as soon as I start spraying there will be a ton of pics. I may even post a video of the spraying. I will have to put the camera in a plastic bag and shoot thru it so I dont get overspray on my camera.

 

[SKIBUM1M]

Re: need advice on paint, gelcoat, duratec

How much time should I allow (minimum and maximum) between coats. Also how much time (again min and max) before applying PVA on top of the 3rd coat? Thanks in advance.

 

[ondarvr]

Re: need advice on paint, gelcoat, duratec

The only reason to do more than one layer is because if the gel coat is thinned for spraying you normally can't build it up enough in one application without it starting to sag.

The window is wide, all you need to do is let the layer before start to gel, at that time you can apply the next one. Or you can wait until its hard, which depending on the temp may be from one hour to three or four.

When I say one application I don't mean one 30 mil pass, you'll need to spray several passes to build it up to the final thickness for that application.

If you thin the gel coat with anything you need to use the same mix each time. Thinning can change the color and look of the gel coat, so if you sand through one layer and into the next you want it to look the same.



Wait a few minutes before you spray the PVA and just fog it on and go slow.

Or you can just wax to the last layer of gel coat, it will do the same thing and is easier.

 

[SKIBUM1M]

Re: need advice on paint, gelcoat, duratec

Has anyone ever used a wagner powersprayer for gelcoat? It sprays house paint unthinned so I would think gelcoat would go thru it pretty well. The acetone may eat it so it may be useless afterward but would it work if I cant get the airgun to work right?

 

[SKIBUM1M]

Re: need advice on paint, gelcoat, duratec

also Is there anything other than acetone that cleans gelcoat out of a gun preferably that does not eat plastic like acetone?

 

[SKIBUM1M]

Re: need advice on paint, gelcoat, duratec

Just in case anyone was following this thread or wants to know whats going on with it. I sprayed the gelcoat unthinned with my wagner sprayer. It worked pretty well except the last quart kicked in the gun. It was a pita but I got it cleaned out. I am now sanding and sanding and sanding. Yes gelcoat is alot of work but not impossible and well worth it imho. For pictures and more information check out my restoration thread link in my signature block.

 

[proshadetree]

Re: need advice on paint, gelcoat, duratec

Did the power sprayer lay it on level?Good to see you didnt give up on it.Going to check out your other thread

 

[SKIBUM1M]

Re: need advice on paint, gelcoat, duratec

It did ok untill the last quart started to kick in the gun and splattered the whole coat. My fault I should have dumped it at the first sign. even with it spraying rough it just ment more sanding.

 

[proshadetree]

Re: need advice on paint, gelcoat, duratec

ever think of a light da sanding the to block out before buffing.Iv done cars this way,seems like it should work on a boat

 

[SKIBUM1M]

Re: need advice on paint, gelcoat, duratec

I am actually doing 3 heavy da sandings. 180, 240, 320 then wet sand 400, 600, 800, 1200, then 2 buffing compounds.