i spray painted this primed piece of MDF. After it dried, the paint seemed
uneven. you can see the overlap parts and other unsightly marks. This was my
first time spray painting so I guess I'll live and learn. however, for this
piece, is there anyway to smooth everything out?
If you want it as smooth as possible (assuming you are using typical spray
paint cans) you should spray the piece with it facing up. Let the paint
fall onto the piece and spray it thick. It won't run that way and you can
avoid some overspray problems.
You may also be able to coat the entire thing in clear... But generally
spray paint is a bad idea if you want a nice finish. We spray the small
parts we use on our drills (www.autodrill.com) but for large parts and/or
high production runs, we have them powder coated. Not sure you can do that
with MDF as it uses static, right?
Some wood finish experts can chime in with better ideas I'm sure.
Joe - V#8013 - '86 VN750 - joe @ yunx .com
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----- Original Message -----
Sent: Thursday, November 25, 2004 3:00 PM
Subject: evening out spray painted piece
Your point is well taken Joe, but really paint is paint. I'd much rather
mix up paint and shoot it with my gun but to the point of spray bombs, one
can get very good results with a bomb. At least, in the context of this
discussion. Like I said, paint is paint and it's much more about how you
put it on than it is about what type of container it's in. I use bombs
frequently, for various small things and I'd bet you could never point out a
piece that was painted with a spray bomb in a lineup. Not that I'd try to
use a bomb for large scale coverage, or for certain types of paint, but for
small scale, it can be perfectly acceptable.
The OP has spray problems that are much more basic than which type of
application he's using. If he's getting the type of blotchy coverage he's
describing, a good gun isn't going to help him any.
Paint from a can, especially lacquer, can be rubbed out to finish
worthy of a classic car. You need to use more coats from a can before
rubbing, as the gun lays a thicker coat.
I've finished many solid body guitars using spray can lacquer and high
quality auto body products to rub it up to a mirror finish.
My local auto body paint store will even custom mix colors in PPG
paints and sell them to you in a spray can.
No kidding... <G>
I usually send owners home with a custom mixed bomb of enamel matched to the
color of their car. Save me from dealing with a lot of pesky stone chip and
scrape touch ups. Spray it in the cap and touch it on with a fine brush.
For larger areas they can mask and spray it if they are even a little bit
Likewise, I've finished a few guitars with bombs. I really prefer one of my
guns for a guitar but there have been times when I just used a bomb.
Not to mention the fact that it needs to be baked in an oven (400
degrees for 15 or 20 minutes, IIRC) You might be able to get the
powder on if the air was dead still, and you let it fall on the piece,
but it'd probably start the wood on fire while the powder was curing,
or at least cause some very nasty warping or cracking.
Canned spray paint can give excellent finishes. If any of the
edge will show, you really need to get it sealed as it will absorb
tons of paint compared to the top surface. A very light sanding
between coats with 220 paper or steel wool will get rid of any
dust nibs that are stuck in the paint.
There are very few, if any, that can achieve finish results in one
coat. Spray again crossing the pattern of your first work. You
will get better results to give it 5 thin coats, than to put it on
too heavy and get runs. The object is to give it a full wet coat
that does not run.
Keep the whole world singing . . . .
DanG (remove the sevens)
If you have runs then sand it down. If it's just blotchy then spray it
again....and again...and...I've just sprayed a bed base using those smallish
cans you get at the DIY. (won't do that again). But, the finish is good. It
just takes a few more coats than you might want to give it. And of course
you only get a finish that is as good as the preparation of the MDF primer.
I sanded each primer coat to 600 wet&dry and the finish is like glass.
(don't do it in the lounge like I did.... next big thing I make that needs
painting is getting built in smaller bits that can be sprayed in the garage
before I assemble the whole damn thing...boy the wife was only upset with
First - contrary to another comment I saw posted here, spray painting is a
perfectly acceptable procedure and will yield excellent results if done
properly. Powder coating does not yield fine finishes. It's a durable
finish but it is not a fine finish. Spray painting is.
Two things will cause an uneven finish. One is bad application. Make sure
when you spray you don't hold the can or gun too far away. No more than 12
inches with a can, 6" with a gun. Spray in slow, even and adjacent coats.
You should not see a dividing line in the overlap between two passes. Each
pass should blend in with the previous pass. You want to spray a wet coat -
which is to say it is flowing on, not dusting on. You want to put it on so
that it shines as it goes on but does not run. Imagine yourself stretching
a piece of thin plastic wrap over the piece. That's how you want your spray
to go on. It's really not a big deal whether you spray with the piece
vertical or horizontal. Horizontal will yield fewer runs, but will puddle
and that will be as big of a problem as a run. Concentrate on getting the
flow right as you spray and not on cheating it. Watch your spray from ahead
of it. Watch it flow on to the piece and gauge your speed and distance by
what you are seeing.
The other thing that will cause your problem is poor surface preparation.
MDF soaks up everything that touches it so you really have to prime it very
heavily, especially on the edges. Very heavily. As many coats as it takes
to achieve a good solid, even color and texture. Knock down any dust nibs
with 600 grit paper and thoroughly clean it. You should not sand down
through the primer when doing this. You're just looking to knock down the
nibs. Use a sanding block to keep from sanding divots into the primer.
Prime in the same manner as I described above. Remember that with something
like MDF or wood, which unlike metal, will soak up paint, you don't want
areas that are sanded through the primer or you'll end up with an uneven
Practice, practice, practice. Shoot on scrap and get a feel for the
technique. You'll screw up a lot, but you'll get it. Post more questions
if you get frustrated.
On 25 Nov 2004 20:00:55 GMT, email@example.com (Ah10201) calmly ranted:
You need to practice a bit more to learn what a wet edge is, Ah.
When you spray, the edges are thinner and can leave dry overspray.
That shows when the paint dries. When painting, you need to overlap
the passes just enough to eliminate that overspraying; to keep the
wet look of the pass intact as you move down. Proper side lighting
helps immensely. It lets you see the gloss of the wet area and keep
Lt your paint dry thoroughly (48 hours should do it) then sand it
down a bit with 320 grit paper and wipe it down with thinner. Let
that dry and give it another coat. It should look better this time
now that you know what to look for.
Drop by a local body shop and ask to watch the painter for a few
minutes. He'll show you precisely what you need to look for if I
didn't explain it well enough.
And check for Andy Charron's "Spray Finishing" book in your library.
PESSIMIST: An optimist with experience
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I was also taught to spray into the overspray. In other words, to
move each pass towards the direction of the spray, so that the bounced
finish from each previous pass is covered with a wet coat.
I really don't know if I'm explaining that right. <G>
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