Filling old holes and touching up Gelcoat

JBlumhorst@aol.com
Thu, 22 Apr 1999 13:06:53 EDT


- - - - - - - - - - - - - - - - - - - - - - - - - - -
West Wight Potter Website at URL
http://www.lesbois.com/wwpotter/
- - - - - - - - - - - - - - - - - - - - - - - - - - -
Hi Webgang,

A few folks have written me to ask about filling holes and gelcoat touchup in
the deck when they move hardware. So here's how I do it.

Regards,
Judy B.

Judith Blumhorst, DC
HMS18/P19 Fleet Cap'n, Potters Yachters
1985 WWP19 #266 Redwing
(Rigged so a petite woman can solo)
Sailing on SF Bay, CA
(5-35 knot winds, 2-4' chop, 2-6' swells, and currents up to 6 knots)
Visit <A HREF="http://members.aol.com/jblumhorst/HomePage/index.htm">Judy B's
West Wight Potter Pages
</A>
and <A HREF="http://songbird.com/potter_yachter/">The Official Web Site of
the Potter Yachters
</A>

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

If these are small diameter holes, under 1/2", I'd do it one of two ways.
Either one is good, it depends on what materials you have at hand.

In both cases, first use clean the area to be repaired as follows: Use a
drill bit to remove any remaining bedding compound inside the hole. Use a
razor to remove any bedding compound on the surface. You may need to use
laquer thinner or acetone as well to clean the area well. Don't use WD40
(which works well to remove gook on gelcoat) because it might get into the
core and mess up your repair.

Method 1:
Materials --
-polyester filler with cream hardener (like Evercoat Formula 27, sold in
hardware stores, marine stores),
-two or three plastic spatulas, (available in automotive stores, hardware
stores, marine stores. You'll find it right near the filler) ( I buy mine at
Tap Plastic. They're very flexible, yellow polyethelyene(?) (like
tupperware). They're about long, double sided and easier to clean with
acetone than the ones you find in hardware stores. I cut them down to about
3" for small jobs like this. Clean them with acetone immediately after each
use.)
-acetone,
-disposable gloves to protect your hands (acetone eats the white latex ones
so wear two, or buy the blue ones from an automotive store or marine store)
-small wood mixing sticks, (tongue depressor, popsilcle sticks. Cut off one
curved end to make it square for better mixing and scraping.)
-several pieces of smooth cardboard for mixing surface for filler putty (or I
use a clipboard with a large ziplock baggy opened up and caught under the
clip. That way I can quickly change the bag on the clipboard for each new
batch of filler or putty)
-gelcoat from IM ($5/half pint) and liquid catalyst (methyethyl ketone
peroxide, I think )(or gelcoat patch kit with ivory coloring agent from
hardware store),
-paper towels, rags.
-three sheets each of wet/dry sandpaper 300, 600, 1200 grit (available in
good hardware stores or automotive stores).
-Unwaxed paper cups make good mixing containers for gelcoat.
-7-day blue masking tape from 3M (not the cheap stuff, buy the good tape)

Step 1: Filling the hole with filler putty

Tape the underside of the hole.

Use water resistant polyester filler to fill the hole as follows: Mix up
the filler according to directions. Using a plastic spatula, mix the creamer
hardener in well according to directions, working it on the cardboard until
the color is even and there are no air bubbles. Use a plastic putty spatula
to work the putty into the hole in several directions to be sure you've
really got enough in there. On your last pass with the spatula, get every
last bit of putty off the deck. Take a cloth dampened in acetone and gently
wipe off the surrounding deck area and just a little out of the hole to make
the surface recessed 1/32-1/16" for putting gelcoat in later.

[ First, practice using the putty on a scrap of wood with a hole drilled into
to get a feel for the putty. Pick a time of day that's under 75 degrees or
the putty will set up too fast, under 5 minutes. If it's hot, you can reduce
the amount of hardener to a little more than half the recommended amount. .
If the putty starts to set up before you're done, QUIT NOW. One more pass
with the spatula and you'll pull all the putty out of the hole. You'll just
make more work for yourself. If you do mess up, wipe as much as you can off
with acetone on a rag and start over]

Once the putty has set up (usually about 20 minutes is plenty, this stuff
sets up REALLY fast), you can apply the topcoat of gelcoat to the hole

Step Two: Applying the top gelcoat from the kit as follows (see below for
instructions on matching color):

Follow directions on the gelcoat patch kit and put gelcoat on the top of the
patched hole. After it's fully cured, wet sand (with a block) using the 300,
then 600, maybe 1200. Wax.

Or if you order gelcoat from IM do the following: Spoon 3 tablespoons (one
oz) of gelcoat into a paper cup. Let it sit in the sun for about 15 minutes
(more or less) to evaporate the solvents and thicken to the consistency of
ketchup or mayonaise. Then add 12-15 drops (less if it's over 75 dgrees) of
liquid catalyst (methylethyl ketone peroxide, you can buy it at any marine
store, automotive store, or good hardware store) and mix well for 60
seconds. Scrape the sides and corners and bottom of the cup to mix the
catalyst in well. Transfer the gelcoat to a new paper cup and throw away the
mixing stick.

Using a new mixing stick, put a dab of gelcoat on the hole. Over fill it a
little, since gelcoat shrinks. Let it cure. When it's hardened to a hard
rubbery consistency (somewhere between 5 min and 1 hour, depending on
temperature), use a razorblade to trim it flat, but leave it a little high.

When it's fully cured(at least 4 hours or longer if its cool out), wet sand
with 300, 600, 1200 grit.

You may need to do the gelcoat thing a second time to get it perfect, since
the gelcoat shrinks. On areas that aren't non-skid, you can spread the
gelcoat with the spatula 1-2 inches past the edges of the hole and then sand
it flat (instead of just filling the hole)

By the way #1, the gelcoat from IM has a surfacing agent in it, so you don't
need to worry about sealing it off from the air to get it to cure.

By the way #2 -- the polyester filler usually comes with red cream hardener.
That's good because you can be sure you've mixed it completely with the grey
filler when there are no more red streaks in it. However, if you can get
white cream hardener, your repair will show less. Just be VERY sure you mix
the cream hardener in very well or else the filler won't cure.
~~~~~~~~~~~~~
Second method. This is how I do it. It makes the repair (almost) 100%
invisible if your gelcoat color matches well. This method uses thickened
gelcoat instead of filling putty to fill the hole.

Additional materials needed: Silica thickener(from West System, Colloidal
Silica #406. Generically also called Cab-0-sil)

Put 1 or 2 oz gelcoat in a mixing cup. Add liquid catalyst (10-15 drops per
oz) and mix well. Add silica thickenr until it's the consistency of warm
peanut butter (the creamy style, not the crunchy style <g>).

Fill the hole, following the directions as described above for putty. At the
end, use a rag wetted with aceton to remove 1/32" off the top ( you want the
hole to be not quite full so you can put in gelcoat as described above.) Let
it cure for 4 hours at 70 degrees, or longer if it's cooler. Aim a shop light
at it to warm it if it's cold)

Put the final coat of gelcoat over it, as described above, using the
evaporated gelcoat from IM. Wet sand with 300, 600, (maybe 1200).

~~~~~~~~~~~~~~~
Color matching:

If you don't get your gelcoat from IM, you'll need to to check the color
match on the gel coat. Here's how to do that

Put about 3-4 oz of gelcoat into a paper cup, or enough to do the whole job.
Add the tiniest amount of ivory you can (1/8" x 1/8" x1/8") and and mix
well. The coloring agent is REALLY concentrated so add it just a bit at a
time.

Don't catalyze it yet! Put a drop of UNcatalyzed gelcoat on the hull and
smear it around with your finger to check the color. Add more white or ivory
to change the color. When you have the color right, wipe it off the boat with
acetone. Now you're ready to get to work.

~~~~~~~~~~~~~~`
That's a lot of instructions. Hope they're not too confusing. It's not as
hard as it sounds. Read the directions carefully on the filler can and the
gelcoat repair kit. If you buy the repair kit, use just a dab of ivory
coloring agent to tone down the base white gelcoat.

One last reminder: Read the directions on the cans at least three times
before you start. Practice first on a piece of wood to get the hang of it.
Make your mistakes on the wood, not your boat.