Another auto clearcoat question

This question has sort of long preamble, so bear with me.
For people out there that have used catalyzed poly-urethane clearcoat. I shot clear today and found out two things. First. Go light over inklines. The first thing I did was shoot one of the control surfaces. Got a bit heavy handed and the ink on the surface melted and bled. Sigh... So, I sanded it down after the clearcoat flashed off and have already repainted the surface with new color coat. I'm just glad it was only one color. What a pain. Anyway, the rest I went over lightly, let it set for 20 minutes then laid on the clear as you're supposed to. Looks pretty good. I'll re-ink the muffed control surface and shoot it with clear tomorrow.

Now to the question. Although the overall finish is pretty good, I have 2 spots where I've got some pretty major runs. I started off using one spray gun and just couldn't get it to lay down the clear right. I suspect the nozzle is just too big. Like 1.8mm. So I ditched it and used my "good" gun and it was fine, but the result was two pretty major runs due to the larger gun. Should have known better. Now, historically, I just use some 1500 grit sandpaper and some Sikkens or similar and block the runs down. And I'll do that here. But does anyone have any words of wisdom on re-shooting the effected area? I really don't want to have to re-shoot another clearcoat on the whole plane. I'm trying to keep the weight down and catalyzed ploy-urethane weighs a ton. Well, not a ton, but a couple of ounces per coat. Is it possible to blend it over the blocked down run?

Thanks for any thoughts. I'm sure I'll figure it out, but just wanted some advice from someone that done it.

I just use some 1500 grit sandpaper and some
>Sikkens or similar and block the runs down. And I'll do that
>here. But does anyone have any words of wisdom on
>re-shooting the effected area? I really don't want to
>have to re-shoot another clearcoat on the whole plane.

Gosh, are you in luck.

I HAVE JUST THE THING!!!

Once again, this technique was taught to me by Bill Wilson.

Go ahead and sand the area and get it flat. Cover whatever you do not want clear on. Tape the immediate area on either a stripe (best to do it on a stripe where two colors meet) or a body line.

Load the gun with some reduced clear (1 to 1 reduced or a little less). LIGHTLY FOG THE AREA. Do not be afraid to shoot a wide fan in short bursts (you did cover the entire plane right?). Maybe only a couple will be neccesary.

Now wait!!!! You will need very little clear! The clear will lay out very nice with very little material on top of the old clear.

Remove the tape in the immediate area while wet. Pour the clear out of the gun. Without cleaning the gun, fill with 5 to 6 oz of reducer (medium or slow--I like slow). Shake up the gun and run an ouce or so out the gun to get the excess clear out of the nozzle. Turn the fan down to about 2" and turn the air down to get a very fine mist like an air brush.

Now you gun has about 1% to 2% clear and 98% reducer in it. Perfect.

Lightly (lightly!!!!) mist the edges of the repair job. Get all the overspray edges. Watch... you will be stunned, 98% of the repair clear will melt into the old clear. Let dry a few days and lightly sand the edges with 1500 grit and hand buff the edges. You will most likely never see the repair.

I have done this several times, including Mr. Hyde before the Nats in several places. Ask Doug...

Geiseke did this same thing on the nose of his Nats front row Bear with Chromaclear.

Brad,

That works? I've used a similar technique with dope, but didn't think it would work with a catalyzed material. I've shot a 90% thinner, 10% clear dope over the edges of an area that has been repaired in order to "blend" the edges of the previously shot clear, but didn't think this technique would work at all with catalyzed clear. That's great!!

Thanks, I will give it a try.

BTW: The Matrix premium clearcoat with the MH006 hardner worked very well. I cut it with Omni reducer 2:1:2 and it ran out fine. It was a little thinnner than I had anticipated which is how I got the runs. Just goes to show, even if you think you know what you're doing, shoot on a test piece first. I could have probably cut it even a bit more.

For all you guys who have used the automotive finishes:
can I shoot 2-part polyurethane clear coat over a conventional dope color job? In other words, if I start the finishing process using the standard dope-and-tissue technique, and take it all the way through the color and inking (with maybe a thin protective coat of dope on top), can I then finish by shooting 1-2 coats of the polyurethane clear, and be done with it? Will there be any adhesion problems?
I'm trying to avoid having to lay down a dozen or so coats of clear dope, since the temp / humidity conditions have to be just perfect (including the correct moon and star alignment) to avoid blush or orange peel with regular dope.

Mike,

Yes, you can do this. I've done it in the past. It does make any repairs that come up problematic, but it works fine in initial application.

>For all you guys who have used the automotive finishes:
>can I shoot 2-part polyurethane clear coat over a
>conventional dope color job?

Works better than dope clear.

Bob G. did the nose of his all Brodak dope 19 point Bear with auto clear.

Phil G. uses an all dope base with auto clear for his beautiful works.

I have use spray can lacquer and dope myself.

Yes clear goes over dope but dope clear cant go over two part paints. Dope uses thinner and it will attack the paint.

Doug,

Yea, and it crinkles all up. Try doing a repair over an open bay. Not a lot of fun. This is my first all non-dope finish. At least if I have to repair it (God forfend), it will all be compatible.

On another note, I fixed the runs (Sheesh!), but ended up having to mask off and re-soot some color coat. Nice to have a decent airbrush. Metallic paints can be such a paint to work with. Anyway, I've got it pretty much repaired and ready for the clear re-coat tomorrow. Just a small area on the bottom to finish fixing. It's not going to win the concours at the Nats, but it shouldn't embarrass me either. I'll let you all know how it comes out.

>On another note, I fixed the runs (Sheesh!), but ended up
>having to mask off and re-soot some color coat. Nice to have
>a decent airbrush. Metallic paints can be such a paint to
>work with.

I had to re-paint the bottom block of the Mr. Hyde after surgery to repair the belcrank moving in the wing. The bottom is Bug cyber green which is multi-colored metallic. I found the secret to be to NOT use a small gun, but instead shoot a big feathered fan in just a few short bursts. The other key was getting the gun back from the surface so as to make it blend.

Of course this means that the entire rest of the plane has to be covered and the immediate area of the repair has to be taped at a color line.

You will never find the Mr. Hyde repair...

'zilla,

I've had pretty good luck using an Iwata airbrush on wide dispersal (or what an artist friend of mine calls "fog") setting. I've got another area that was just going to ignore, but since the first correction came out so well, I'm going to go ahead an fix it. I mean, it's not like I could fly much right now. Weatherman says rain starting this afternoon...continuing through next Tuesday.

Anybody go a boat?

I think this is the near standard body shop spot repair method--they even use spot repair reducer and spray the edges of a wet spot coat with 100% thinner. It makes the boundary nearly invisible.

>I think this is the near standard body shop spot repair
>method--they even use spot repair reducer and spray the
>edges of a wet spot coat with 100% thinner. It makes the
>boundary nearly invisible.
>
>Curt

Valspar makes a "blending reducer". Bill is convinced it is just reducer with a little urethane resin in it. I think it is imperative to have the 1% to 2% reducer in the reducer. Slicks out much better.

LAST EDITED ON Jan-27-04 AT 01:53 PM (CDT)
 
Yes--that is propbably correct. Makes sense.

Come to think of it, it might be worth a try to see how light a finish you can really put down!