One thing you're going to find is that an HVLP gun that has a small enough
fluid tip is not easily found without spending some money. Make super sure
you contact S-III tech support and ask a lot of questions here, and don't
fudge on anything. As far as I know, S-III water-reducible LPU is one of
the toughest coatings to spray well. I survived the process, but the
results could've been finer. Note: I have a DeVilbiss gun and it wasn't
'quite' the right thing, close but not quite. The only ones I saw that let
you go low enough on fluid tip size and had reasonable flow rates that would
work with my compressor were Binks guns. Here's my learnings (in addition
to practice, practice, practice with your spray system and the paint):

Prep and Notes:
- S-III LPU is like a defect-magnifier ...surface preparation, including a
fine and ultra smooth layer of primer, is of ultimate importance. S-III
paint is tough as nails, looks fine, but is cures to a very thin layer that
highlights defects
- I found it necessary to put the clear coat on (they call it 'optional')
and the final finish was still what I'd call 'satin', not 'gloss'. I'd call
the paint without the clear coat 'duller satin'.
- Do not do a large project until well experienced
- When painting in patches (how else?), the paint does not re-flow into
previous patches well. You must spray fast, heavy as you can without
causing runs and sags (this takes judgment), and figure out a spraying
sequence of events that lets you spray only near fresh paint. Example: Mask
off bottom of boat and transom, then spray around perimeter of the boat
sides, starting at one transom corner and ending at the other. After
curing, mask off the sides and spray the bottom and transom.
- The primer cures first by drying (water evaporates and the primer feels
dry) then by curing (epoxy) ...it takes closer to 3 days for a primer coat
to be fully cured. The primer is tough as nails too (good stuff), so sand
early not late. Sand after it dries, but before it 'cures'.
- The paint cures/dries in a funny way. At first, it skins over, then
dries to the point where it feels like a rubbery latex coating (not
sandable), then over the space of a couple of days cures to a harder finish
that you can sand. It is completely cured in 2 or 3 weeks in a warm shop
and it only gets tougher ...same rule as the primer: sand as soon as it is
sandable, not later.
- The catalyst is optional and makes the paint even harder to sand. I only
put it in the last coat and the total result is completely satisfactory in
how tough the paint system is. The only real drawback to the S-III paint is
that it takes experience to apply well and it cures quite thin and so
highlights defects. It is not a high-gloss system.

Application of the primer or paint:
- Spray a couple of cans of water through the shop first to humidify the
place as much as possible
- Thin as described on the label
- Use a very thin fluid tip ...atomizaton is very important with these
products ...not forgiving of a large nozzle (call their tech support and
press them for numbers)
- Do not use too wide of a pattern (outer edges will dry on the way to the
boat)
- Spray heavy enough to allow some re-flow, but not so heavy that the paint
sags or drips. HINT: A cool shop will cause you problems. Make sure you
are at around 70 F or so ...cooler and it may sag, warmer and it cures too
fast.
- Spray your boat in a pattern that avoids overspray onto previously coated
sections ...if more than just a couple of minutes has passed, the paint will
not reflow well and you'll get a 'dull' look where the overspray occurred.

Good luck! It's a good and tough paint system, but being water based
requires skill and experience to apply well.

Brian

--
My boat project: http://www.advantagecomposites.com/tongass


"Doug" wrote in message
om...
I am going to buy a pressure feed hvlp gun to spray System Three LPU.
Any help that you could give me regarding your experience with
different gun models, fluid tip sizes and LPU thinning would be
helpful. I am looking at new, used and import guns.

Thanks

Doug