Question about gelcoat spraying for Rich H and the rest of the gang.

[Dan H]

I am re-gelcoating my boat. What I'm having trouble with is getting a very crisp line at the boottop. What is the best way to get a crisp edge where two colors meet?
I am spraying .025" thick. I tape off the stripe with 5 layers of 3M 213 fine-line tape.
The process that has worked the best so far is spraying the gelcoat and letting it cure hard. Then I sand the gelcoat that is on the top layer of tape until I have a crisp line and then pull the tape. I am still getting a little chipping along the edge of the line. This process is costly at 5 layers of tape and the sanding is time consuming.
What is the best way to get a very crisp edge to the gelcoat where two colors meet and still achieve a very thick buildup?

 

[James V]

gelcoat

Dan

Have you considered letting the gelcoat set up and then removing the tape?

Jim

 

[aa.aunins]

I know nothing about spraying gelcoat, but with every thing I do work with, paint, caulking stuff like that it is best to let things set up half way then remove the tape while the applied product is still soft.

I have learned that your work piece is the last place you want to get "on the job training". I would find something like a board or old boat hull to try different techniques on until you find one that you are happy with. That way you are only working with small areas and you can test two or three ways at a time.

 

[sailaway78]

Not sure if this will work

I have never done this on gel coat, but have done it with paint and it works very well. Learned this from my son, who is a real pro painter. On cars that is. What is happening is that the gel coat is stuck to the edge of the paint. When you pull the tape, it pulls some of the gel coat with it. Take a good sharp double edge razor blade, a carpet knife works well, and lightly scribe a line along the edge of the tape. This will let the edge of the tape release from the painted surface.

 

[r.w.landau]

The problem is that polyester resin,

Gel coat or lay-up, it is thick enough to need to be reinforced. You already have 20 mils of un reinforced gelcoat on the baot and you are adding 25 more mils. That may be another problem later.
It will be hard to make a crisp line, You should be able to sand then buff those. If you are hand sanding, Go to a palm sander with 220 paper then clean it up from there. 25 mils is a lot of gel coat. Don't be bashfull.
Next question,
Why do you want an obvious step to the boot strip?
r.w.landau

 

[sailingdog]

One problem with laying gelcoat that thick is that it'll be far more likely to crack or craze.

 

[Dan H]

R.W.,
I'm re-gelcoating the entire boat. I need to spray the boot and cove first. Then when I srpay the rest of the gelcoat and sand, it will all be one level surface with permanent stripes, just like it came out of the mold.
How do they do stripes in the molds I wonder?

 

[Maine Sail]

Dan..

I agree with some of the others. Be very careful in your gelcoat thickness. Thick gelcoat crazes and cracks. It's a fine line between too thin and too thick. Cape Dory was famous for laying on the gelcoat too thick and as a result many cape Dory boas have considerable crazing. Track a few downa dn you'll see what I mean.. Personally I'd rather err on the side of too thin rather than too thick. Dremeling, filling and fairing crazing is not fun future work..:cry:

The easy way to do the boot and cove is to do the hull one color then paint the toe and boot with a durable two part marine paint such as Interlux Perfection. This with the fine line tape will look amazing!

How are you air inhibiting the gel for cure???

If you're not to far into it you might consider one of the two part urethanes like Interlux Perfection..?? Without a mold Gel can be very finicky and tough to work with..

One more thing if you are using WaxSol or any sort of wax based air inhibitor for cure then you need to wash with Solvent wash 202 De-Waxer or equivalent and sand before applying any more gelcoat or paint. This wax must be removed for good reslults before proceeding to any further hull work..

 

[Dan H]

I'm using Duratech HGA to thin and cure the gelcoat. It air cures just like paint. Sprays just like paint but thicker.

I'm spraying about .025". After it cures it measures .020 - .018. After sanding I'm hoping for .015"

I could spray the field color and paint the boottop and cove, then in a few years paint the boottop again and again This way, when I'm done, I'm done.
Obviously I'll need to take care of the gelcoat but I'm hoping for a permanent finish.
http://www.duratec1.com/Application_Guides/ag7.pdf

 

[Maine Sail]

This way, when I'm done, I'm done.
Obviously I'll need to take care of the gelcoat but I'm hoping for a permanent finish.
http://www.duratec1.com/Application_Guides/ag7.pdf

Unfortunately the reality is that nothing on a boat is permanent.:cussing: You're also NEVER "done"..

.015 - .018 is fine and should not crack and craze. The way I read it was that you'd have areas approaching .050 mil.

You seem to have all the answers and have formed your opinions around "paint" so I won't dwell too much. Just know that a top quality two part paint such as Imron, Sterling, Awlcraft 2000 or AlexSeal will last longer before requiring any sort of yearly maintenance than any gelcoat will. I'm NOT a gelcoat hater and in fact it is exactly teh opposite and I'm about he biggest gelcoat supporter you'll find here on SBO but paint is a good idea for a cove and boot for a number of reasons.

You can expect a minimum of 10+ years of service if you do nothing to them and considerably more if you maintain them using the right products. Two part coatings are NOT regular paints!!

Tim R's Ericson (below) has a fire engine red Imron finish, the most fade prone color, and it's approaching the 19-20 year mark. I think the picture says it all. .015 mills of a colored gelcoat will be wearing quite thin by the 19-20 year mark as it will require more "attention" than the white.

You'll also spend far more time maintaining, compounding, polishing and waxing a gelcoat finish than you will with a cove and boot paint every 10+ years maybe 19 or 20. Another consideration is that colors other than white or off white in gelcoat have substantially shorter life spans. Green, red, navy, royal blue will all fade significantly faster than the white hull..

19-20 year old red Imron..