How To Repair and Refinish Interior Plastic Pieces

How to Repair & Refinish
Interior Plastic Pieces
by Lars Grimsrud
SVE Automotive
Restoration
Musclecar, Collector & Exotic Auto Repair &
Restoration
Broomfield, CO
Rev. New 5-7-01
Having seen some pretty rough-looking
‘Vette interiors, and some rougher-looking ‘Vette interior
repair & refinish jobs, I thought I’d put together a little how-to
on making your black plastic panels look better than new
again.
Supplies needed:
(All supplies are available from most
automotive paint supply stores. I have had very good luck with the PPG
stores and dealers)
1 qt can PPG Wax, Grease & Silicone Remover (part #
DX330)
1 gal PPG Vinyl Prep/conditioner (part # DX103) or -
1 pt
bottle SEM Plastic Prep or SEM Vinyl Prep (part# 38348)
1 aerosol can
SEM Original Trim Black Trim Paint (part # 39143)
1 aerosol can SEM
Vinyl & Plastic Color Spray (part # 452340)
1 kit SEM Rigid SEM-Weld II
plastic repair compound (part # 39508)
Lint-free paper towels
(available in big, cheap bundles at the paint supply store)
Tack
cloth
600-grit wet-or-dry sandpaper
Grey Scotchbrite pad
The
black plastic dash and console panels in your C4 are not bare plastic. The
are coated with what GM calls “Dulso.” This is what gives
them the unique satin black appearance, but it’s also what makes
them difficult to keep looking nice: as you rub and clean them, the Dulso
wears off, leaving shiny plastic areas. The Dulso also stains if you
spill things like acidic soft drinks on it, like Mountain Dew. A good
refinishing process is certainly needed…
Before starting an
interior refinish job, you need to be aware of the single biggest problem
with interior parts: Silicone contamination. Interior “care”
products, such as Armor-All, Son-Of-A-Gun, and others, contain HUGE
amounts of silicone. Once this had been sprayed on interior parts, it is
extremely difficult to remove. Silicone is a painter’s worst
nightmare: even the slightest amount of silicone will cause primers and
paints to “fisheye,” separate, and loose adhesion. Not good.
in order to do a good plastic refinish job, we must first address
preparation and silicone removal.
Silicone cannot be removed by
sanding or abrading (like with a Scotch-Brite pad or SOS pad). In fact,
any attempt to sand or abrade the parts to clean them will embed the
silicone into the parts, and you will be doomed to failure. DO NOT sand
the parts before doing a good cleanup on them.
First clean the
parts in hot water with dishsoap in it. Use a sponge (something
non-abrasive) and put some effort into it. Rinse them off and dry them.
Dump out the contaminated water and don’t use it again on the parts.
I have an automatic parts cleaner at my house: my wife thinks it’s
a dishwasher, but I know it’s an automotive parts cleaner. Just
turn the drier heat “off” before running your plastic parts
through it. I leave the heat “on” and put it on the
“potscrubber’ cycle when I run rods and pistons through it (I
don’t understand why this upsets my wife: don’t they advertise
that these machines remove caked-on grease…?).
Next, use your
silicone remover, following the directions on the bottle. You will soak a
lint-free paper towel, wipe once in one direction, flip it over, and do it
again. Then throw that towel away and do it again with a fresh one. If
you wipe back and forth with the same towel, all you will do is smear the
invisible silicone all over the parts with no gain. So do the one-wipe
thing and use up some of those cheap towels you just bought. Once
you’ve done this several times to all the parts, give them a
wipe-down with the grease and wax remover, using the same
technique.
The parts should now be about as contaminant-free as
they’re going to get. If they have nicks or etched-in
imperfections, you can now use some sandpaper or Scotchbrite to smooth
them out. If they are cracked or damaged, clean the damaged area with the
SEM Plastic Prep and use the SEM-Weld II two-part plastic repair kit to
fill the damage and sand it out like body filler. It sands really nice,
and is easy to form. If you sand the parts, make sure that the parts do
not have a finish any coarser than a wet 600-grit finish when you’re
done: anything less (even wet 400-grit) will leave visible scratch marks
in the finished product.
Final prep step is to clean the parts
completely with the SEM Plastic Prep or Vinyl Prep. This stuff actually
slightly softens and dissolves the surface of the parts, and makes the
surface “fuse” itself to the paint you will apply. So
don’t rub aggressively with these prep products: follow the label
directions and give the parts a gentle wipe-down. Rinse with water. If
your parts are perfectly prepared, the water will “sheen” off
the parts and will not separate or “break.” This is known as
a “water break free surface condition,” and indicates a
contaminant-free, clean surface. Dry the parts.
The SEM Trim Paint
is actually an exterior trim paint product, but it works perfectly on the
‘Vette metal parts in the dash, like the lid for the cup holder.
The Vinyl and Plastic Color Spray is to be used on all of the plastic
parts. Lay out your parts and lightly go over them with the tack cloth to
remove any dust or particles. Apply the first couple of coats of paint
very light and fairly dry, in a criss-cross pattern to assure coverage.
Observe if you are getting any fish-eying or separations. If you are, the
areas that are fish-eying must be coated with VERY light and VERY dry
coats at first until they are covered with the paint, allowing the paint
to dry between these coats. Be patient. Don’t try to cover it all
with a big wet coat at first. Once you have complete coverage with your
light mist coats and this has dried to a tack-free state, lay down two
medium, even coats. This will give you a perfect, even, beautiful sheen
to your parts.
Install the parts back in your ‘Vette and
admire how good of a painter you are!
For additional info on SEM
products, or for a distributor near you, contact them at:
SEM Products
1-800-831-1122