REFLECTOR: Painting with Awlgrip

Bob Jackson bobj at computer.org
Sat Jul 2 15:33:50 CDT 2005


Ronnie,

A few more comments:

1.  Mixing Proportions.  Did you weigh gallons of the AWLgrip topcoat, the
converter and the reducer and they were all the same weight?  I would be
surprised, but I didn't try it.  The directions say mix by volume, so if the
densities are different, mixing by weight could change the proportions
significantly.  I would assume the topcoat is much denser than either the
converter or reducer, and if so you'll be using too little converter and
reducer, which contributes to orange peel -- on the other hand, it would
minimize runs.  Using 30% reducer by volume to minimize orange peel
definitely makes runs more likely!

2.  Partial Coats.  I agree with Scott -- if you want to use AWLgrip, I
would do everything possible (including 'exotic' wing stands, etc.) to be
able to paint things like the canard, the control surfaces and the wings in
one shot.  I don't think you'll be happy with the overlap seams if you paint
the bottom and top of the wing, for example, in two steps.  In our case the
very bottom of the fuselage at least will be a different color so we don't
have to paint the entire thing in one step -- but if we were not doing a
'two-tone' design, I would definitely try to figure out some kind of rig to
allow painting the entire fuselage (canard, wing, etc.) in one step.

3.  Problem Correction with AWLgrip -- not as bad as it seems.  Even if you
can't get all two or three coats of AWLgrip down without excessive orange
peel, runs, or 'dry' spots doesn't mean you have to try over and over to
paint all three in one clean series.  I try to paint all three coats in one
session, then if there's a problem, let it dry sand out the problem, scuff
the rest (with 3M foam-sand pads, for example), and a couple of days later,
paint a single, final, topcoat.  So really, you only have to get one final
coat right.  Of course, if you're lucky and get all two/three coats on OK,
then you can do the whole thing in one session.

4.  Anti Orange Peel Additive.  Scott -- you mentioned the availability of
this additive -- can you give us a part #?  This could be very helpful,
because as it is we seem to need 30% reducer to minimize orange peel, and
that makes it more susceptible to runs.

5.  Outside Temperature and Humidity.  We have no choice in Orlando -- the
humidity is almost always over 75% and often higher (especially when it's
raining!!), so I'm not sure you should be too worried about that in deciding
when/if to paint.  AWLgrip 'standard conditions' are 77 deg F and 50%
humidity, but that doesn't mean you can't use it successfully in other
conditions.

6.  AWLgrip vs. Other Paints.  To Al's question about the PPG paints -- we
haven't done a physical comparison of AWLgrip with the PPG (or Dupont)
paints.  Obviously, you can achieve a great paint job with any of them.  I
believe that the AWLgrip 2000 version is more similar to the PPG Deltron and
Concept.  I think they're all 'acrylic' urethanes and two step paints (i.e.,
the second step is a clear top coat).  AWLgrip (and I think Dupont IMRON)
are both 'polyester' polyurethanes, which are supposed to be quite a bit
more durable and also flexible, which can be important for paint on
airplanes.

Don't lose faith, Ronnie!  If you can get the AWLgrip on (without orange
peel, the drys, or runs) I think you will be very happy -- it looks great
and is supposed to be extremely durable.  We were not able to paint our
fuselage this morning due to a thunderstorm.  This is probably not the right
time to be trying to paint a plane in Florida!

Bob


-----Original Message-----
From: Ron Brown [mailto:romott at adelphia.net]
Sent: Saturday, July 02, 2005 8:17 AM
To: bobj at computer.org; Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: Painting with Awlgrip

Good morning Bob!

You're up early or late going to bed!  Thanks for taking the time for your
excellent responses - I needed the moral support!!!

I will comment on each of your items in the text below:

----- Original Message -----
From: "Bob Jackson" <bobj at computer.org>
To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
Sent: Saturday, July 02, 2005 3:18 AM
Subject: RE: REFLECTOR: Painting with Awlgrip

> Hello Ronnie,
>
> Glad to hear you're painting now with AWLgrip -- here are my comments and
> questions:
>
> a)  you've got to wait at least 30-45 minutes between coats, i.e., for
> them
> to "flash off" first before going on to the next coat.  Waiting longer
> helps
> reduce the chance for runs.  We've usually been waiting 1 1/2 hours or so.
> If you don't wait long enough the next coat may not be able to flow and
> flatten properly.  I've had problems with what look like dry areas when
> coming immediately back over an area just painted, even though I'm sure
> there should be plenty of paint there.  In this manner, the early second
> coat may have created the "seeds" for the third coat orange peel.  How
> long
> did you wait between coats?

I waited about 30-45 minutes, looking for tacky feel to the paint.  It was
pretty sticky.  I'm thinking I could have waited a bit longer - with your
suggested 1.5 hours, I will certainly try that.

>
> b)  The AWLgrip literature says the first coat should be slightly wet,
> with
> the next coats (what sounds to me like full-) wet coats.  I know Scott
> said
> he had good luck with a full wet first coat, then lighter and lighter
> second
> and third coats.  But, I think if you shoot too dry of a second or third
> coat, there won't be enough there to re-flow and level out, perhaps in
> this
> way you created the orange peel by not getting enough on with the second
> coat.
>
A good friend of mine also made the comment that if the first coat of
Awlgrip is too dry, it just causes orange peel in the following layer(s).
Too bad you can't just apply one coat - my first coat was gorgeous!!!!  And
only one run on the end of an elevator where I shot the end and got too much
paint on the adjacent surface.

> c)  the first coat seems to be the key for us in minimizing orange peel.
> It's got to be what I would call a full wet coat otherwise it forms the
> "seeds" for later orange peel.  Also, I think I get the best coats if I
> put
> each on in a single pass.  Common practice would dictate putting a coat on
> in two passes, each perpendicular to the other to ensure a more even
> coverage.  But with AWLgrip the second pass, even though just a few
> minutes
> from the first, can look dry and doesn't always seem to flow in with the
> first pass.
>
> d)  I like 30% reducer for similar temperature and humidity conditions to
> yours, like we get here in Florida.  This seemed to be a key for us in
> minimizing orange peel.  But the literature says if you reduce beyond the
> recommended 20-25% you will need three, not the more usual two coats to
> get
> the required thickness.

I was very surprised at how well the Awlgrip covered.  I used Bondo
surfacing putty to fill in little nicks and pinholes that the primer didn't
cover.  This putty is dark red.  The Awlgrip covered it very nicely on the
second coat.
>
> e)  I've been told that 10 psi is the maximum you can use and still be
> considered HVLP.  We've been using 6 psi.  You may possibly be getting too
> much paint (and air) out at 10 psi and somehow that's contributing to
> orange
> peel.

I will try lowering the pressure to 6 psi.

>
> f)  Why did you paint just single sides of each control surface?  You can
> not blend together coats of AWLgrip where coat edges meet, like on the
> leading edge of the elevators.  We've been hanging ours up, with extra
> lines
> to prevent them from turning from the force of the spray, and painting the
> entire control surfaces in one step.  AWLgrip is not like two step
> paints --
> it's a base coat and top coat all in one (unless you're using AWLgrip
> 2000,
> which is a two step version).  There is no way to buff out the seams and
> overspray areas between two adjoining AWLgrip coats.

As I mentioned earlier, my purpose in just painting the bottoms is to learn
as I go.  I will tape, mask and sand the bottom nose of the elevators (only
place that there is an overlapping area) when painting the top sides.  This
joint will pretty much hide behind the canard.  I am planning on doing the
same for the noses of the canard and wing, with the paint joint on the
underside of the nose.  There is a lot less chance of runs if the surfaces
are flat - hence painting the bottoms separately from the tops.  Hopefully,
by the time I get to the fuselage, I will have the runs under control! (???)

> g)  Are you sure about the 40 sq ft and 29 ounce numbers?  My rough
> calculation for what you said you painted was only about 27 sq ft, but
> using
> your 40 and 210 sq ft/gal number, 40/210 x 128 oz = 24 oz.  Also, although
> we haven't keep accurate usage numbers, I was thinking we were getting
> more
> like 300 sq ft/gal coverage, but I could be wrong on this.  It depends a
> lot
> on the spray efficiency you're getting (how much overspray).  With smaller
> items like you painted I think efficiency might be a little higher than
> with
> large areas like wings and fuselage because it's a more "controlled"
> situation.

Awlgrip certainly covers better than the stated 210 sq feet per gallon.  And
by the way, my ounces are weighed ounces (16 oz per pound) instead of fluid
ounces.  A gallon of mixed paint weighs 9.34 pounds or 149 oz per gallon.
I'm using my postal scales to weigh out the exact amount of paint (color,
converter and reducer).  Oh and by the way, included in this painting batch
was the bottom cowl - sorry I left that out.


> h)  AWLgrip seems to be touchy WRT orange peel, but one thing to remember
> is
> that once it drys and you take it out into the direct sunlight, it becomes
> much harder to see the orange peel.  AWLgrip has such a deep shine, and
> with
> the diffuse light of direct sun, you tend not to see the orange peel.  I
> think that's why we've been advised that the worst error is the "drys",
> not
> orange peel or runs which are harder to notice in the sunlight.

I am headed to the airport this morning and will pull the pieces out into
the sun.  Being in the dark hanger with light coming in at an  angle
parallel to the surface certainly makes things look worse (like a ceiling
lamp shining across sheet rock - sure shows up the joints!!!)
>
> We'll be AWLgrip painting the fuselage tomorrow morning -- I'll let you
> know
> if we learn something more new from that.  With the temperatures now in
> the
> 90's, the AWLgrip literature also says we should be using almost 50/50
> blend
> of T003 and T005 reducers.  I think this is to avoid too fast of solvent
> evaporation and the resulting "solvent pop" pock marks, which we've seen
> almost none of so far.
>
I am only using the standard T003 reducer and saw no solvent pops, so I'll
stay away from the high temperature T005.  Let me know how it goes with the
fuselage!!!  I will paint the bottom of one of my wings today if the
humidity will get down to something closer to 50%.  Forecast is 60% at 2 pm.
Learning as I go!!!  Ain't homebuilding fun!!!

At least I have enough paint per your and my calculations - less than 2.2
gallons mixed paint for the whole 173 Elite.

AGAIN, THANKS!!!!!!!!!!!!!
Ronnie

> Good luck,
> Bob Jackson
>
>
> -----Original Message-----
> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]On
> Behalf Of Ron Brown
> Sent: Friday, July 01, 2005 5:12 PM
> To: reflector at tvbf.org
> Subject: REFLECTOR: Painting with Awlgrip
>
> I shot the bottom of my control surfaces today.  Temperature was 91 but
> with
> humidity of 49%
>
> I got a beautiful first coat - light but wet finish.  The second coat was
> shot after it started getting tacky.  It came out a little dry looking -
> still trying to keep it from getting too thick.  The third coat, light
> again
> but wet turned into orange peel.
>
> Did I shoot the first coat too wet?  I used the standard reducer in a HF
> HVLP gun (10 psi on the regulator) and mixed the reducer to 30%.
>
> By the way, after shooting the 3 coats, I still had 6 oz left.  I
> calculated
> the standard coverage of 210 sq feet per gallon.  I shot the bottoms of
> the
> control surfaces, one side of each rudder and the main gear leg doors.
> Equals 40 sq feet and calculated to take 29 ounces of mixed paint but only
> needed 23 ounces to cover with three coats.
>
> Thanks for the help AND HAVE A HAPPY FOURTH OF JULY!!!!
> Ronnie
>
>
>
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