On Fri, 06 Aug 2004 12:04:45 -0400, "
wrote:

On Fri, 06 Aug 2004 16:54:47 GMT, "Yves" wrote:

I need some advice for paintinf mdf doors (Spray).

I used to spray lacquer with sealer over wood.

But If I want some other color on MDF, what product is best.

I don't know what type of product gives the best finish, or on what type of
paint can I put laquer on , or should I use lacquer at all.

Couple of opaque colored waterbased finishes available for spraying.
See www.homesteadfinishing.com as Jeff has a tinting machine for
matching commercial colors.

I've heard great things about products from Homestead, but have never
used them. I have used the Magnalac series from M.L. Campbell
(http://www.mlcampbell.com/pages/home.asp) quite a bit. The antiqued
yellow look is apparently "hot" these days, so we've been using quite
a bit of the MagnaMax White/Opaque Base that's been pigmented to match
the customer's color preference. Prior to this, however, we use
Magnalac Primer/Undercoater as the base coat.

A few things I've recently learned - I'm posting them here for those
who may be in the position I was about 2 months ago!

- Sand well, especially on any freshly exposed MDF areas. We only
sand the hardwood frames (usually poplar) to 120, but we take the MDF
to 220. Any tiny knotholes, cracks, dips or gasp gaps in the joints
will show up much more clearly with paint than they will with
clearcoat. You can putty after the primer (as well as after a coat of
the lacquer itself), but it's more efficient to try and do it all at
once,and proprly,the first go-round.
- When applying the primer, you needn't go real heavy when you band
the edges, as they'll get hit again when you do the other side. Plus,
since they are vertical surfaces they are more prone to drip. I take
a quick pass on all four edges and then lay on a thick coat across the
surface.
- After banding, I align the door so the long edge points into the
spray booth. It seems to make it easier for me to get even overlaps,
and thus even coverage. Then I stand just off the back right corner
of the door (I'm a lefty), angle the gun 10 to 15 degrees into the
booth and start on the nearest corner, moving the gun back and forth
across the board. Paint is much easier to see from a coverage
perspective, but still can present problems with bubbling, dry spray
and overspray. I *think* I hold the gun a little closer to the work
and move a little quicker back and forth. The first one or two passes
should cover the nearest rail/stile and now you're on to the junction
of the panel and the frame. This is where it gets just a little
tricky (for me). I've learned to sort of roll my wrist under a little
bit to get the spray to hit the inside edge of the board you just
sprayed. It's just for one pass, but it can really make a difference.
From there on out it's just a back and forth motion with a little
wrist action so the inside edges of the frame get touched with finish.
I go pretty heavy.
- After priming the first side, we only let it dry for an hour or so
before flipping them to do the front. When doing a full kitchen
there's no delay at all. After everything's primed, we let it sit
overnight before sanding.
- The next day you'll want to get your sanding station really well
equipped. I cut up a bunch of 220 squares for the quarter sheet
sander and for hand sanding, grab a can of putty and a couple
different knives, hook up an airhose with a blower nozzle (VERY
important) and get the whole stack of them set up right where I can
grab them. Since you didn't have any drips or runs, you won't need
any scrapers or pads in the vise....
- First off, I grab a door and check to see what needs puttying. If
it needs it, I make sure to cut away enough finish so it will stay
seated, and then I take pains to not glop it on there. A quick pass
with the putty knife should leave a nice smooth, slightly elevated
surface. Don't mess too much with it or it'll dry out enough to get
grainy and pull away. If it needed puttying, I set it aside at the
end of the line. If not...
- Then I whack both sides with the quarter sheet sander, and quickly
blow it off to remove the swarf. If you don't, it's likely to clump
up and reattach itself to the door. Since you'll be blowing dust all
day (you'll look like a drywaller) you definitely want to wear a good
mask. Better yet, have a dedicated sanding station equipped with dust
collection. We don't have one, so I put away the DustBeeGone and
break out the Dustfoe 88. It just feels like it's providing more
protection.
- Next I pass over the edges. making sure to knock down the little
burr of finish that's frequently there. Don't worry too much about
going through the primer, because the pigmented lacquer will cover it.
- Next up, I hand sand the profiles. I play around with folding the
sandpaper this way and that for a while, and then settle on "the best"
method - and then repeat it for each and every door. It makes it
easier for me to be sure I've hit all of the surface and provides a
level of consistency about which I'm a bit anal.
- Lastly, I blow off the door and then work surface. I give the door
a final runover with my hands to feel for rough spots, and then set it
in the "done" stack. Next door.

I'm sure I've forgotten some things, but that's the gist of it for me.

JP
****************
You'll need a sharp chisel to clean up the miters too.