Spot priming/painting fuselage

[Zzz]

This topic came up in the other thread about powder coating and reminded me that I've no idea what the best technique for touch-up is on the QB fuselage. I've got a few places where the packaged parts riding inside the fuse rubbed the paint down to metal. I also plan to do a little welding, so I'll need to touch up. I have zero painting experience other than some wet sanded rattle can work when I was young.

I got some of the 2-part paint from Mark that AviPro uses. Can I use a light duty HVLP gun? My compressor is nothing to write home about but for spot shooting will that be adequate?

For prep, is it as easy as rattle canning a little zinc chromate? If not, what should I prime with?

Thanks.

[N942VT]

For spot repair on your fuselage a good quality rattle can self etching primer should be fine, I like SEM products self etch. There is a big difference in the cheepo rattle can paints, don't fall for the price. Better though would be to do all your welding and repairs then mix up a small cup of 2 part epoxy like Poly Fiber's EP-420 or Stewarts Ekopoxy. If you're doing just a little at a time you can turn the gun fan way down and you should have enough air. Just make sure everything is good and clean before you shoot. Don't worry too much, most of the tubes get covered or painted over later anyway.
Dave

[jaredyates]

I think the main concern is just to be sure that before you cover, any paint that you've applied is not going to be lifted by the covering process. This is more likely to be a problem with Polyfiber than Stewart systems. Like Dave says, you can spray a rattle can primer as you go, and then apply an epoxy all at once at the end if necessary.

[Zzz]

So... a little epoxy primer overlapping the Avipro paint is no problem?

Jared, what was that paint color match that you found that matches the stock Avipro paint? Ford tractor something...

[N942VT]

Scuff up the existing paint and any to be re coated prior to priming, a grey 3M scuff sheet works well. The color on my frame was Juneau white. I resprayed it Insignia white.

[bestbearhawk1231]

ZZZ, I use an Iwata LPH-400 spray gun with my crappy air compressor. It is one of the only ones I found that I could use with my compressor which optimistically claims 4 cfm. It runs non stop when spraying the small parts and I will probably "T" another air compressor to mine when spraying the wings and fuse once I get to that point. The Iwata runs in the neighborhood of 12-16 psi at the regulator which is lower than the SATAs and others I tried, part of the reason my air compressor was able to keep up. The spray gun is ungodly expensive ($450 or so) but the cheap Home Depot gun I had had wasted so much paint that I couldn't see across the shop when spraying small wing parts. The Iwata has an amazing transfer rate and atomizes the paint like you wouldn't believe. If you are planning on painting your aircraft yourself, the gun will pay for itself in paint savings. Anything that is a SATA or a SATA knock off you need a pretty good air compressor since they are air hogs, my air compressor didn't stand a chance at keeping up. Devilbiss makes a pretty good gun also and they are easier on the wallet. I use an Iwata simply because I had a good friend trick me into trying his on a few parts...I couldn't go back to the cheaper guns after that...they are really that nice. Make sure you use a disposable air filter at the gun but before the gun mounted regulator. Make sure to drain the tank on your air compressor before you start and use a good respirator. Make sure you have good supply of fresh air, solvent based paints will screw up your world really fast if you don't have a fresh air supply... oh ya, turn off the furnace in your shop before you start spraying solvent based paint. Scuff the surrounding area with a scotch brite pad, wipe clean with a solvent ( reducer, MEK, Acetone, rubbing alcohol, etc... the reducer called for by your paint is a safe bet) and then mix the paint. Check your gun pattern on a piece of cardboard before you get close to the plane so you can get things adjusted right to reduce the runs, drips, and sags. I use water to get my gun close then run a bit of Iso alcohol through it to dry it out and do the final adjustments with paint...but I am also using Stewarts paint which is water borne so a bit of water only thins it a bit more.

I would recommend priming steel parts with an epoxy primer that is compatible with your top coat.

Hope this helps out, if you have any other questions, let me know.

[jaredyates]

I didn't bother with matching the paint color. I just painted all of the exposed tubes with the new color. If you peek into the tail, the shade is different, but then that's what you get for being nosy.

[Zzz]

I have some steel priming to do finally. I have new skylight welded in, and some other welds here and there. I think I'm going to try the Stewart's Ekopoxy 2-part.

Any other opinions?

[Battson]

Use whatever Bearhawk Aircraft uses - it's the best I've seen. I think they just use a standard epoxy primer, and it's the top coat which does all the work.

[Glenn Patterson]

The Stewarts Ekopoxy will work great. We used all Stewart Systems product for our project. Degrease well then scuff with the 3M 7447 red scuff pads, degrease again then prime. Safest is to use one family of paint products so there are no incompatibility issues. We buy the 3M 07447 scuff pads by the box from an auto paint supplier. The red pads give the right tooth for the primer to bond to the metal. Norton 180 or 220 non clog sand paper works well. The key to successful painting is to wipe down the surfaces with degreaser to remove skin oils etc before sanding so the oils are not worked into the surface being sanded. Prior to painting. If you are using Stewarts Systems then use tack cloths that are for water bourne paints. They should be available at NAPA or a seller of auto paints. Regular tack cloths are not friendly to water paint products. 70% isopropyl is a good degreaser between steps for Stewarts Products. I use a more aggressive degreaser on bare metal for the first clean prior to sanding the mill scale as there could be process oils on the steel.

One thing that cannot be over emphasized with Stewarts Systems & every other environmentally friendly paint is that they are as dangerous to a person as the conventional paints. Read the MSDS sheets for the paints. Always use a respirator preferably a full face with cartridges for paint. An acquaintance told me that he sprayed urethane without a mask & was not feeling good. I told him that he needed to read the MSDS as it could seriously hurt him. He told me that he read the MSDS sheets & then he bought a full face mask because the paint supplier said that urethanes are linked to eye cancers.

The SS part B urethane hardener is every bit as dangerous as conventional urethane hardener to humans. I have painted cars & trucks with the proper safety equipment for painting. With the Stewarts we used the respirators, tyvek coveralls to protect the body, nitrile gloves & built an effective temporary paint booth that had an air change about every minute. All the Eco friendly paints sound safe but the only product used that is safe is the water. It is "eco friendly" because it is not gassing off the volatile solvents. I developed a mild sensitivity to urethane while painting our BH that affects my breathing. My partner took over painting . If I continue it will get worse with each exposure. I knew that people can take serious reactions to conventional urethanes to the point where they may end up at emergency in severe respiratory distress. The hardener in regular paints & water paints or urethanes are mainly isocyanates which are dangerous to humans. The hardeners for epoxies are dangerous in their own right & the product precautions should be followed.

Zinc chromate primer is nasty because of the chromium, Chromium affects the body so use a mask when spraying the zinc chromate in a well ventilated area. I looked after the welding program and I was approached by the maintenance manager which a corporate mandate to make sure welders & trademen were safe with respect to chromium. Welders are exposed to chromium with alloy welding & painters with chromiums in paint products. Key is to ensure adequate ventilation and use respirators.

My intent is not to scare you but to keep you safe as one unfamiliar with paint. To raise awareness that care & safety should be used with paint whether it is a rattle can, bulk product or "eco" friendly. Read the MSDS safety sheets & follow the recommended personal safety requirements. WIth proper safety equipment & good adequate ventilation a person can get the job done safely & be healthy to fly when the airplane is finished.
Glenn
BH727

[jaredyates]

Compatibility with upcoming products is still the primary concern. Is the Stewarts product susceptible to being dissolved by the Polyfiber products, or are you planning to use Stewarts for the covering?

[Zzz]

Compatibility with upcoming products is still the primary concern. Is the Stewarts product susceptible to being dissolved by the Polyfiber products, or are you planning to use Stewarts for the covering?

I'm using the Stewart's system.

[Glenn Patterson]

Agreed x2 with compatibility of paint & fabric systems.

I am not going to advocate one brand over another. We worked in a 26 x 55 shop with a 14 ft ceiling heated with a Valley comfort wood. We would warm the shop up to about 90F when it was -30F outside to primer. The advantage of water bourne paint & fabric systems is no risk of blowing the shop up with volatile solvent atmosphere. A lot of time & money is invested in building an airplane so it is best to stick with one manufacturer to have peace of mind.

[Chris In Milwaukee]

I wasn't aware of Polyfiber products dissolving the Stewart's stuff. It's an epoxy primer, so I thought it was like any other epoxy primer and wouldn't be attacked by "foreign products". I guess I need to look into that.

[jaredyates]

I don't want to imply that they aren't compatible, rather just that it's worth verifying.

[Chris In Milwaukee]

Oh yes, definitely! :-)

I know that you can't use the paint systems together. Mainly because Poly* paints are essentially liquid vinyl (based on my recollections from the fabric class at OSH this past winter), and Stewart uses different compounds.

Definitely going to verify before using either.

[whee]

I don't know if that is true, but it could be. I know some guys use Stewart's up till paint then they switch to PolyFiber.