Gel Spraying Techniques

Back home and back to work on the 87 SN. Only half of one side still needs to be filled. Then I can start sanding in prep for the gelcote.

Yeah glad to have you back Bill. I thought you were home a little early but can't wait to see more photos of your progress.

Bill:

Everytime I see your pictures, I am in awe of your hard work and dedication. Believe me, I know how difficult a task you have undertaken.

Can I make a picky observation? Oh well, here it is anyway...you should remove the bow eye before you gelcoat (if not too late). Why? Well, it will be better if the gelcoat is contiguous (sp?) under the eye. The gel will be more likely to flake, crack and peel if terminated around the perimeter of the eye. Plus it will just be a cleaner look ultimately. All you have to do is remove the nuts from the inside and pull it out.

I looked up that gel spray rig you purchased from US Composites. My oppinion is that you would get better results by using an automotive spray gun and thinning the gelcoat. The gun you are using is for applying gel to molds before the fiberglass is laid up. When spraying molds, it does not matter how much orange peel there is because the surface against the mold will be smooth no matter what. Also, you want fast build-up and thus a lot of gel out of the gun at one time. Just my thoughts...I could be all wet on this as I have never seen or used the gun you have.

Bill, After you posted buying the gun, I too looked at it on US Composites web site and my impression of it was the same as Davids! I think you would be better off with a regular gun with the proper fluid tips which will give you a decent fan spray pattern. There are spray additives that are said to do a better job than styrene. They only have a 90 day shelf life though. I've never used them, just the styrene. Have you looked at any of them? I have heard that the new product of Mini-Craft that was reported on a earlier post, (the high gloss orange no sand) may be gel that simply comes pre mixed with the spray additive.

Looking good!! Sorry to hear that the bow eye wouldn't come off!

I just read through the entire listing. It is good to start with a smooth surface, so your prep work seems to be the way to go. I used a remote pressurized gun. Not expensive and it worked well pumping up the thick gelcoat. This way you don’t have to thin it. You’re going to get orange peel no matter what you do, so don't worry about it. Put the special wax in the finial coat and wet sand with an orbital sander. The wax will cause the gel to dry without a sticky finish. I used a porter cable electric one and it worked great. Start coarse and work to a 500 then 1000 wet paper. I used a liquid rubbing compound (pink stuff) to buff it out. It came out great.

Regarding mixing color. You can do it in batches, but make sure you buy your base gelcoat at the same time. Then pay close attention to the amount of color added to the first batch and do the exact same thing each time. I do mean the exact amount. A syringe with a cc rating works well. Drop by drop also does.

Good luck,

Gary

Bill, You know that you have done lots of wet sanding when the water bucket you are using is turning pink! That's from the tips of your fingers bleeding!

Bill, one nice thing about runs in gel is that since it's catalized, the run is hard unlike normal paints which are soft under the surface. We have all been there!!

My wife asked if I was about finished yet. I explained that I have half-finsihed sanding half of one side of the bottom of the boat. She was not amused. It is snowing outside so it still doesn't matter but the clock is ticking.

Last night I applied gelcote thinned heavily with styrene from a pressure gun. It gave a much smoother finish than I was getting before. Today I applied trace on the new gelcote. Then I used an orbital sander with 120 grit and knocked down the bumps. I followed with the orbital and 220 grit sanding until the trace was light grey. Then I wet sanded with 500 grit until I was soaked and all the trace was gone. Looks pretty good so far.

Problems are that I am out of gelcote for a few days and I am concerned that maybe I have not made it thick enough. I know it is supposed to be 22mils and I have a thickness guage. I am thinking the 22mils should be the final depth after sanding. I have two quarter sized dark spots where I sanded so much the dark color of the hull shows through.

Anybody got an idea on how I can make sure I get the gelcote thick enough but not too thick to cause problems later?

Thanks

Since I ran out of white gelcote I started on the blue stripe. Taped it off with blue tape and paper. Applied four coats at 8psi with my pressure gun. Used overlapping circular strokes like waxing. The last coat I added wax. Only did the one side. I have enough left to do the back. Trying to figure out how to remove the tape without damaging the gelcote. As I see it I am making progress.

I hate to tell you I told you so on the spray gun, but I am glad you tried it. When I repaired my boat, it took at least two and most of the time three coats of get to get good thickness. If you have a high spot that you sanded through, then you will continue to sand through on subsequent application of gel. You need to sand the high spot down before applying the second coat.

You should pull the tape immediately after spraying and before the gel kicks.

Warning: Make sure ALL traces of the tracer are gone before apply a second coat of gel or you just might end up with a nasty black halo in spots.

Keep up the good work.

Bill, Just wax the last coat. It really is just a sanding aid because it floats to the surface sealing the gel preventing the tackyness. It is also said to be a lubricate for dry sanding.

I sanded down the blue stripe and it turned out pretty good. It is still plenty thick. I taped off the stripe and mixed up some white. Sprayed on the white and right after I cleaned the gun I removed the tape. Once it dried I sanded down the bad spots and applied a second coat. Sniffing fumes and waiting for the second coat to dry right now. This system should produce a pretty good finish.

Thanks again Pete and Dave.

Yes, I think I agree with that. In fact on my boat, if I had one very minor low spot, I would forgo the sanding block and use my hand to get into the low spot. Impossible to notice on the final product. Pinholes and divots are something else.

Thanks for all the support. I sprayed a final layer of white gelcote below the blue stripe on the stern and right side. It was the smoothest finish so far. I am sure that is because I sanded between layers. I just started wet sanding that area. My plan is to hit it once with the 400 grit then finish what I started below the boat. Not getting to spend as much time working on the boat as I wish I could but I'll keep at it.

I am determined to get this project finished. Spent a few hours sanding then cleaning the side and bottom of the hull. Then sprayed on the first layer of white gel on top of the blue stripe. Took two shots to get it all. The first I bungled at the bow and made some big orange peel. The second I bungled by over-thinning causing it to run like crazy. The bottom already had one coat of white that was sanded. I mixed it just a little too thick. Three sprays and I jacked up all of them.

Not worried. I mixed in wax. I will dry sand with 320 to smooth it all out. The next spray can only be better.