Hi! Mark Corke here from BoatUS Magazine. Today I'm going to show you how to repair a large
area of gelcoat by using a disposable sprayer. So before I get started, I'm going to wash this down,
but the whole reason for this repair is the fact that there is a previous repair here.
I can see it close up -- you probably can't see it on the camera. But what I want to do is
sand this down again, spray this so it matches the surrounding, gelcoat, and it's far easier to
do that with a disposable sprayer than trying to do it with a brush. So the first step is to use
good boat soap and some water to wash the area down that'll get any surface dirt off there.
With the soapy business finished, I'm going to rinse it down with some clean water just to get
the soap off the surface. With the rinsing out of the way, next step is just to dry it
off. I'll wipe up as much as I can with a rag, then I've got to leave it to air dry.
Safety is very important, so you'll notice I'm wearing safety glasses. I've got disposable
gloves on, and I'm wearing overalls because I don't want to get this acetone all over myself.
Also, when I come to actually doing the fiberglass work, I'll be wearing a respirator.
So before we mask off, I'm going to wipe down the area with acetone just to get any
remaining contaminants off there -- any wax or detergent that's left over from the water.
So we don't get gelcoat everywhere, I'm putting plenty of plastic down, painters tape masking
off the area so that any overspray doesn't go on my boat and it doesn't go on the deck
or on that handrail -- and more importantly, I want to make sure that I don't get any
blowing off on the boat next door [UP TEMPO MUSIC]
There we are. That should do it. [GUITAR STRUMMING]
Incidentally, here's a really handy tip. If you're using masking tape,
keep it in a Ziploc bag. That way, when you put it down, you don't pick up dirt on the
edge. So if you're painting anything, you get a nice sharp edge without any fluffy bits on it.
Before we actually apply the gelcoat, the next thing is just to give it a quick rubdown with
some wet and dry paper used wet. This is 400 grit, and all that does it just gives a bit of tooth
or a bit of bite for the gelcoat to actually attach. You'll notice that I'm using a block,
and that keeps it nice and flat against here so we don't put any ridges in the gelcoat.
We're just going to wipe this down with some nice clean water and then let that air dry,
and we'll be good to go. [GUITAR STRUMMING]
We get loads of questions about should i use waxed or unwaxed gelcoat?
I'm using wax gelcoat, but either will work. The difference is that if I use wax gelcoat, the wax
floats to the surface as it dries, keeps out the air, and allows it to harden.
If you're using unwaxed, that won't happen and you either got to cover it with something
or cover it with PVA, which will exclude the air and allow it to harden. [GUITAR STRUMMING]
The gelcoat I'm using is precolored to match my boat. It's obviously Spectrum Color -- that's
just one manufacturer. There's lots of others, but if you go to the website you
can buy it for almost any boat precolored so it'll match your gelcoat precisely.
One of the main things that we need to do when we're spraying gelcoat is obviously have some kind
of sprayer. Now, if you're doing a large area, you would use a compressor, and we're not at
that stage. We're going to do a very small repair, and for that I'm going to use a pre-valve sprayer.
These are great. You can buy these almost any hardware store and essentially it's a
can of propellant with a glass jar. I'm going to put gelcoat in there,
and then that will obviously spray that onto the boat. So now we're ready to mix things
up. I'm obviously going to use the gelcoat, and I'm going to use 5 ounces of gelcoat,
which should be enough for my repair. Obviously I've got to catalyze that, which is this stuff,
and then I'm going to reduce it with styrene. In other words, I'm going to thin it slightly because
it comes out through the spray gun easily. Once I've mixed all the components together,
I'm going to put it in the glass jar, then we can go around to the side of the boat and spray.
I've let the gelcoat cure, and it's nice and hard now. Next thing is to remove the masking so that
I can then sand it and feather the edges in so it'll match in seamlessly with its surrounding
gelcoat. [UP TEMPO MUSIC] So we've taken off the masking, and already it's starting to look
pretty good, but we're not finished yet. To make it blend in with the surrounding area,
I'm going to use some 600 grit wet and dry used wet wrapped around the block.
I can use a fine paper because spraying the gelcoat already gives you a smooth finish, so
we don't need to be too aggressive with this.
That all feels really good. It's nice and smooth, there's no bumps or hollows or
anything in that now, so we're almost complete. Wipe off the sanding residue with a clean,
damp cloth. The next stage after we've sanded it and it's nice and smooth and it's looking good,
we're going to put some rubbing compound on there. I use 3M Marine Rubbing Compound.
It's basically just an abrasive but in liquid form. So we put some of that on a rag.
Some people use the rubbing compound directly on the pad, and I can do that, and I do do
that when I'm doing large areas, but for small areas, I tend to use a rag because it doesn't
fling the stuff everywhere. So the next step after I've rubbed on the compound is to use my
slow speed buffer. This has got a variable speed and I'm going to be running this at
about a thousand revolutions per minute. And you'll also notice I've got a yellow
buffing pad on here so it's not too aggressive because I don't want to take too much off,
but I'm just going to polish this with this. [MACHINE WHIRRING]
With the compounding out the way, the next stage is to use a glaze, and we get loads of questions
about this. But this is basically a very very fine polish. It's still slightly abrasive but
it's a fine polish. This will put a nice shine on here. I'm going to add a little bit with my cloth,
and then before that dries, I'm going to pick up my buffer again and I'm still
using the same pad but I've reversed it so I've got a nice clean surface,
not using the side that had the compound. I'm using the buffer at the same speed
as I did for the compound and we don't want to go too fast. [MACHINE WHIRRING]
Now that's looking pretty good. It's nice and shiny, and it's blending in much much better
with the existing gelcoat. The final stage is to use a nice wax to protect the polish that we've
just put on. I like to use Collinite fiberglass boat wax. There's plenty of others, but this is my
preferred choice, and i've always had good results with this. I'm going to apply this by hand.
The last stage is I like to polish this off by hand. You can use a buffer,
but i like to do it with a microfiber cloth. In case you're wondering what tools and materials
were used I'm going to put those in the description so you can find those yourself.
Anyway, I hope you learned something here today, and I'd like to thank you for watching,
and we'll see you on the water! [WAVES LAPPING]