I'll cc the list so others can add comments.
On Thu, 25 Aug 1994 S.G.Adderson@ukc.ac.uk wrote:
> I know I should really go out and buy a book on paint spraying
It would be money well-spent.
> but I'd be most grateful for some practical advice.
>
> This weekend I shall be attemping to respray my car. I have a
> small compressor (8 cfm, 25ltr, 2HP - yes I *know* it's too
> small) and a 1.2 nozzle spray gun.
>
> How do I set up the air and paint mixture? Do I put the
> compressor on max, open the air screw right up then open the
> paint screw until I get a reasonable mist or what?
>
In general, no. Choose a lacquer thinner formulated for the expected
temperature. Thinners for hot temperatures dry slower than those for
colder temps; if you use a hot temp thinner on a cold day you will get
good gloss but very slow drying and it will be tricky to avoid runs.
I routinely use a thinner for hotter temperatures than actual to reduce
later buffing, but for a first effort I would not do this.
Thin the paint according to mfgr's recommendations. The can will usually
recommend a pressure for spraying, often 40 pounds/in2 at the gun. Put
the paint feed and air screws in mid range. Then test the pattern by
holding the gun about 6-8" from a piece of cardboard and pulling the
trigger for a second. If there is little paint feed, open the paint
screw. If the pattern of paint deposition is round, increase air
feed. If the pattern is figure-8 shaped, decrease the air feed. You want
an oval pattern 8" high and about 2-3" wide.
Practice. The paint feed should coat the metal evenly and completely as
the gun is moved at a comfortable pace, and the air should be adjusted to
give an oval pattern so that overlapping strokes give an even film.
> How long should I wait inbetween coats? I'll be using a primer > first
then the colour a few days later. It's cellulose paint > by the way. > >
Wait for the paint to "flash over" (lose its wet gloss). If you are
applying lacquer to the whole car with a small compressor, you are
unlikely to have to worry much about recoating too soon. The bigger
problem is that the paint will have too long to dry between coats, and you
will have to do a lot of color sanding and buffing. If you are not using
metallic lacquer, I recommend masking the car into two or three sections,
and finishing one before going to the next.
Do not apply lacquer on a damp day. (In england, that is probably like
saying don't paint.) Excessive moisture can cause paint to have whitish
patches.
If you have not bought your paint yet, I recommend acrylic lacquer rather
than cellulose. It is more durable and just as easy to use. It can be
used with a conventional respirator.
Thanks very much for any useful hints & tips. > > > Steve - more at home
covered in oil and grease than in paint > with a 1966 Morris Mini Minor in
almond green (well, sort of).
Ray Gibbons Dept. of Molecular Physiology & Biophysics
Univ. of Vermont College of Medicine, Burlington, VT
gibbons@northpole.med.uvm.edu (802) 656-8910
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