Chris,
I've used Imron and Imron industrial on my planes for 20 years and I love and
hate
the paint.
As 51 commented, I too made the mistake of painting urethane without proper
ventilation/protection
back in the 80s. Nasty stuff. I was lucky, as soon as I
realized I was "poisoned" I ran out of the booth and stopped trying to paint
without
proper equipment. I will occasionally paint in the shop (like one wing
top) with only a good mask and lots of ventilation, but I am extremely careful
now.
Orange peel and urethane are inseparable. You are right, there are degrees of
orange peel. Some are visible but when you run your hand over the skin, it
squeaks
and feels slick. That kind of orange peel is fine with me.
When Johnny (my painter) was still able, he could shoot even industrial Imron
dead
smooth. He used a Binx #7 and moved extremely fast and steady laying a light
wet coat at about 30 PSI, followed by a medium at 70 PSI then the final at
120 PSI. The paint cloud was horrible, but he could get it smooth just about
every time. Once cured on top to the touch, he would mist the plane with water.
Keeping the paint cool or it would orange peel in the hot Florida days.
He said the key was a good 150 PSI compressor that put out cool dry air. An air
conditioned paint booth was a must in Florida. A gun that atomizes extremely
well, and of course good technique and overlap consistency. (At his home he
painted at night in the cool fall and used water to cool the paint.) Once the
government forced him to go to HVLP guns, he never got the technique down again.
Using the HVLP guns (DeVilbiss mostly) the Imron serious orange peel started
us cutting and buffing for a week on the last few planes he did for me.
He and his guys could clear coat pretty well with today's car base coat clear
coat urethanes with the HVLP but on old style high solids urethanes, it remained
a challenge. I've seen Aerothane go on smooth using an HVLP with 1.3 nozzle
and it was still a bit lumpy without reducing, but not bad so they seem to
be doing it right. However, Johnny's guys did not like Aerothane as they never
got the settings right (of course they never read instructions either). For
that much money per gallon it should go on perfectly. The only car paint I've
ever put on an airplane was a brand called Autobaun from Germany. It was a very
nice paint. Expensive but still not as hard and wear resistant as Imron or
aircraft quality paints.
Imron, like most urethanes is so sensitive to flash, temperature and gun
settings
that it would orange peel just looking at it. If the air supply isn't dry,
the humidity and temp controlled in the booth and the part also cool I can't
do a nice HVLP job. The factory rep came to the body shop and he couldnt get
the Imron industrial not to orange peel. Dupont called for a first coat of
medium
wet using a 1.1 nozzle. Then two more medium wet coats. The aileron looked
like a golf ball finish. We found like A51 said, doing it on the flat with
a HVLP with a larger nozzle helped on the thicker paints. I can't emphasize
enough that these aircraft paints like to go onto a cool surface (70F or so)
and prefer cool air or they flash. I got rid of my turbine gun years ago
because
of the heat they added. I hear reducers help but in my experience, keep it
cool and let it cure at 75F or below overnight.
Cutting and buffing became a way of life for paint finishers with urethane if
you
wanted that glass finish. I've even tried adding the roller additive we used
on boats for roll and tipping, and a reducer which cut the orange peel somewhat,
but it was still somewhat there.
I hate doing the labor, but if you put enough paint on, then cut and buff
starting
with 800 wet sanded on significant orange peel then 1000, 1200, 1500, 2000,
3000, 4000 changing pads frequently and then buffing at low speed with fine
compounds, you can get a glass finish in only a weeks worth of work. If you put
on the paint very thick here in Florida's summer heat and try to cut it, you
can often see microscopic air bubbles in the paint if it dried too fast on top
and trapped the air in the paint. In that case, wet sand all the way down
to the primer and start over.
When it is done well, it sure does look pretty once polished out. Problem is we
don't do it often enough to get the learning curve firmly set in our brain.
So, today, once it dries, I'm back to cut and buff. I'm still not motivated
to paint the top of my wing delamination repair. Primer sure looks good, but
I've got to scuff the top, tape and drape and get psyched up to finish this
project.
Best Regards,
Bud Yerly
-----Original Message-----
From: owner-europa-list-server@matronics.com
<owner-europa-list-server@matronics.com>
On Behalf Of Area-51
Sent: Thursday, July 13, 2023 3:52 AM
Subject: Europa-List: Re: Making an Europa pretty
All valid and wise... It's an aircraft, not a static show pony at the hotrod
meet
where guys debate near useless aspects of OCD cosmetic indulgence found nowhere
else except in the fashion industry.
And it is white.
There are actually some paint guys that can get a glass mirror finish off the
gun.
All they do is top coat paint and nothing else; and they sure charge for it.
They number very few. In the olden days brushes were of the finest sable and
the pot of paint was heated to get the paint to flow out flat; then it was all
finished in wax.
Orange peel is controlled by several factors; the pressure exiting the nozzle,
the amount of paint metering through the nozzle, the flash time factored by the
amount of reducer/extender added in the mix, temperature and stability while
inside the booth. The longer the flash time the more the paint will flatten out,
partly why rotisseries are used, but the more opportinity for dust, runs and
bugs to ruin the show. What ever panel can be laid flat the better.
Flow coating clear will build the depth illusion; not really noticeable on white
unless it has a fleck or pearl factor in the base coat. And it will turn
slightly
yellow as it ages. Not really necessary. Better off going for three to four
coats of base colour and leaving it to cure if it meets the grade.
I painted a car in a home made garage booth with Glasurit system in 1987; it was
a great finish straight off the gun and never got cut or buffed. 35 years after
it still looked as good as the day it was assembled with just a wash chamois
and wax. And was ill with mild cyanide poisoning for the first two enjoyable
years.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=511092#511092
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