J small and large paint touch ups

[Thedude]

I recently got this plane and I want to fix up some minor paint issues as well as a larger bare spot. Some seem to still have primer and some seem to go down all the way to the metal. I'm looking for recommendations on what I can do now to clean it up and prevent any issues that may come.

 

 

[Mark942]

I'm also interested in other people's experience with this. My E is probably overall in worse shape with paint than his. I've been upgrading and restoring my plane for 5 years and it flies Great and is becoming very mechanically sound, but the paint sucks.  I really don't want to spend north of $20K to have it repainted, although I know that is what attracts a new buyer. I'm 73 so I won't be flying too many more years and will need to sell. I'm a DIY guy and have a very experienced and good AP/AI that helps me. Thank you "TheDude" for starting this thread.

[anthonydesmet]

I’m also interested to see where this goes. I’ve been wanting to do this for awhile.  My mechanic has walked me through it but I have never pulled the trigger.  We walked through the different sanding grits (can’t remember) and pre coat/corrosion. But then many questions like - do you use an air compressor sprayer, what nozzle, do you need a catalyst, do you use a clear coat….yada yada ….so standing by for someone to walk us through this from start to finish.

 

thanks Dude!

[Rwsavory]

Find a shop willing to do small-scale paint jobs. Most likely candidates will be in rural areas.

[Marc_B]

This is a good thread.  But I think the issue is to properly clean and prepare the exposed metal to coat with paint.  Just sealing over corrosion won't fix it.  But if you try to sand down to bare metal you may be removing the alclad surface layer.

For small touchups I went down to my local auto paint store with my access panel (has all the colors in use on the aircraft) and had them color match a two part paint match in a spray can.  You can spray in a container and use a brush to apply with small chips.  But once you activate the paint you have 24 hours to use it.  Cost about $30 for a can.

[anthonydesmet]

46 minutes ago, Marc_B said:

But I think the issue is to properly clean and prepare the exposed metal to coat with paint.  Just sealing over corrosion won't fix it.  But if you try to sand down to bare metal you may be removing the alclad surface layer.

Yes, you will want to prep by sanding and feathering an area larger than the bear spot so your patch is smooth around the edges then prep with zinc chromate I am told.  
 

I like the idea of the paint shop putting it in a ready to use can and not messing with an air compressor or brush.

[Utah20Gflyer]

I’m doing this now, in fact I spent several hours at the airport this morning taping off the area I’m redoing next, maybe tomorrow morning.   In my case I have large areas of sun faded blue metallic paint that I am restoring.  My white paint has flaked off and chipped in a few areas which I’m going to start addressing once I’m done with the blue.  I anticipate the whole project costing maybe 1k.  So the money isn’t bad but all the prep of sanding, cleaning and taping off is a real killer.  
 

So if you have lots of time and motivation you can make a plane look really nice with very little money.  Maybe I’ll post a few pics. 

[kortopates]

The paint has to have good adhesion to make it worthwhile to touch up. But picts look like paint is peeling off indicating the prep on the original paint job was sub-par.
It’s really not worth trying to patch up the paint if it’s that the case. Just like it’s not worth trying to patch a leaky tank if the sealant is in poor shape.
I suggest to go visit a professional paint shop and see if they think the paint is in good enough shape to patch but i bet they’ll tell you the problem now is because the prior job was very poorly done. This isn’t a little touch up either but a lot.


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[Brandt]

2 hours ago, kortopates said:

The paint has to have good adhesion to make it worthwhile to touch up. But picts look like paint is peeling off indicating the prep on the original paint job was sub-par.
It’s really not worth trying to patch up the paint if it’s that the case. Just like it’s not worth trying to patch a leaky tank if the sealant is in poor shape.
I suggest to go visit a professional paint shop and see if they think the paint is in good enough shape to patch but i bet they’ll tell you the problem now is because the prior job was very poorly done. This isn’t a little touch up either but a lot.


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So couldn’t you sand down to aluminum and redo the alodine to prepare the surface?  Haven’t tried it.  Just curious.

[kortopates]

9 minutes ago, Brandt said:

So couldn’t you sand down to aluminum and redo the alodine to prepare the surface?  Haven’t tried it.  Just curious.

You have to do that very carefully, since you don't want to sand the bare aluminum and sand off the thin Alclad surface.  The Alclad surface provides corrosion protection for for the underlying aluminum alloy. But as you try to remove the loose surrounding paint it will likely keep flaking off. There are also signs in places where it appears the prior paint job wasn't stripped fully but just painted over (but could be signs of prior owner touch up too). It would be very easy to ruin the aluminums skins without the proper professional guidance/supervision in prepping bare aluminum.  

[RoundTwo]

I’ve got an issue of filiform corrosion around rivets in several places that I’m attacking every now and then. I have tried multiple methods of mechanical paint removal, but by far, the best way has been the Harbor Freight soda blaster to clean each small area without affecting neighboring paint. 
 

At first I tried it without a compressed air drier and it was a tortuous job. Now that the air runs through the refrigerated drier, it’s a cinch. 
 

After paint removal, I feather each spot then treat with etch, Alodine, epoxy primer and top coat.

[jamesyql]

Following!

I also recently purchased a J with some rough paint spots including leading edges. I have been trying gentle wet sand (200-600 grit), a product called final wash, acid etch spray on primer and colour matched spray cans from a local auto body supplier.

To answer someone’s earlier question : single colour no clear coat unless metallic is what I have been told for airplanes. Single stage “1K” paint (no catalyst needed) is how they mix up the spray cans for me. 2K paint needs a catalyst. 

So far I have made very little progress. Other challenges are doing this outdoors to avoid overspray to other aircraft, and the bugs that come with being outdoors. 

Any tips welcome!

The remainder of the paint is flat and oxidized so going to have it buffed and see if I can avoid a paint job and put my money where it really counts… certified aircraft parts

Quote on a paint job up here in Canada is $35k CAD ($26k USD)

I am the exact opposite of an expert on this, so take everything above as hypothesis until you do your own fact checking

[ArtVandelay]

If you know the colors, you can order paint from here:

https://www.aerotouchups.com

I’ve never used them , so I don’t know if what they have is better than going to auto paint shop. I do know that they can’t match white, the subtle differences between white colors won’t match up perfectly.

[Thedude]

Thanks for the advice here, this sounds more complicated than I was hoping for... I live pretty close to artcraftpaint.com, I'm going to reach out to them for advice and I'll let everyone know what they say.

[PT20J]

Mine is doing the same thing. I live on a field with a museum that has a restoration shop and a paint guru and I’ve discussed with him ways to touch it up. It’s a lot of work to do it right, so I keep putting it off. And, the longer I have waited, the more areas need attention. I have finally concluded that I’d be playing whack-a-mole and it’s time to get it painted. The paint is original from 1994. Paint doesn’t last forever. 

[Pinecone]

Small chips are best painted with an artist's paint brush.  You want to fill the chip to the level of the surrounding paint without getting any of the new paint on the oil paint which makes a bump.

Larger areas need to be feathered to the new paint and sprayed.  I would recommend a high quality airbrush to do this.  I have a Grex that would be great.  A little larger than your hobby airbrush, almost like a very small paint gun.

Doing paint touchup well is almost like being an artist painting a painting.  

[PT20J]

The problem my paint guy explained to me with painting larger areas is that polyurethane isn’t designed to blend by feathering by sanding. It has a minimum film thickness and when you sand it down thinner it will eventually show a witness line. All the pros I talked to want to paint entire panels to avoid this problem.

[Pinecone]

4 hours ago, PT20J said:

The problem my paint guy explained to me with painting larger areas is that polyurethane isn’t designed to blend by feathering by sanding. It has a minimum film thickness and when you sand it down thinner it will eventually show a witness line. All the pros I talked to want to paint entire panels to avoid this problem.

That is best.

Yo can paint to the seams and no blending.

[MikeOH]

7 hours ago, PT20J said:

The problem my paint guy explained to me with painting larger areas is that polyurethane isn’t designed to blend by feathering by sanding. It has a minimum film thickness and when you sand it down thinner it will eventually show a witness line. All the pros I talked to want to paint entire panels to avoid this problem.

While very true, I view the issue a bit differently.

Namely, right now I have some larger areas (a few square inches on leading edges) with missing paint; those areas are, not surprisingly, rather obvious and ugly.  If I can even poorly feather and fill those areas the fact there is a 'witness line' visible up close is still WAY BETTER than the ugly bare spots now visible.  That I can do this myself for not much money is far preferable to spending >$20K to paint the whole plane, or entire panels!  My paint is near 30 year old Imron and still is in good condition with good shine...touching up the bare spots, even if not perfect, for little money sounds like a pretty good compromise to me

[Utah20Gflyer]

As others have said you don’t want to sand bare aluminum because of the Alclad layer.  The technique I use for this situation is I prep the bare aluminum with alodine and then spray the area with primer.  The transition will be very noticeable but at this stage that’s ok.  Take a small piece of 400 grit sand paper and use your finger tip to sand just that transition line.  The goal is to remove the line without going through the primer.   If you begin to go through, apply more primer and then continue.   Once the line is gone spray again with primer and sand again.   Use Wet/dry sandpaper and use plenty of water.  Then you should be ready to spray your color coat.  
 

This probably sounds time consuming because it is, but it’s also very cheap if you don’t value your time.   You’ll probably never get a 10/10 paint job but I think you can get it to an 8 with some effort.  
 

here is a before and after from last weekends work,  keep in mind I need to wet sand and buff the clear coat to even out the sheen,  currently it looks a little splotchy.  I also need to respray the silver stripe.  While I’m doing the one in the blue I’ll also respray the one above in the White.  
 

This project probably took 8 hours of labor so far and is not complete.   All but an hour was monotonous sanding, cleaning and taping.  
 

 

[Utah20Gflyer]

Here a little better picture of the results.  The second picture shows the one spot where the transition is noticeable.  With some forethought you can hide the transitions a lot of the time.  All in all I think it’s a big improvement.  FYI I took the picture in a way that made the transition as noticeable as possible.  Few people would see it at 10 feet.  

[Pinecone]

Just realize that any paint line forward of the spar may hurt performance.  

According to Bob Kromer, just waxing the leading edge, top and bottom, back to the spar is good for 2 knots.