Touch Up Paint

[jetdriven]

4 hours ago, Seth said:

I'm following this thread.  Very fascinating.  I'm not the best artist but I can mechanically make things work.  I'll practice on some scrap prior to touching up the airplane, but this could be a great way for me to touch up my leading edge and other small areas.

I do have the paint codes for my airplane.

And if I mess it up, I can always go to a real paint shop and have them remove my bad work and respray the leading edge and other areas.

The problem is my hangar does not have high walls and there's a lot of dust/particulate in there.  I wonder how this will harm the finish of my paint job/touch up

-Seth

i wouldn t attempt to spray anything in the hangars we got, even a rattle can spray job of a small bracket. That spray can carry a very long way and next thing you have 3 other plane owners demanding a repaint on their plane or a sand and buff because of overspray.  This goes even for hangars with real walls.

[Davidv]

49 minutes ago, Seth said:

Around 3k was my quoted price for leading edge and other touch up areas.  But those quotes are old now and I’d need new quotes.

-Seth

Between the paint (AF-400) and other supplies it probably cost around $250 and that would have been enough paint to touch up the entire plane.  I just did the tail sections.  The downside is that the finish isn’t as glossy as the original paint but unless you’re looking under a shop light it’s tough to tell.  Is it perfect or as good as a paint shop? No way.  However, the color matched extremely well from Finishmasters and the “brighter” leading edges below are mostly from the light outside the hangar.  @jerrodmonaghan was kind enough to help me with the job as well as applying some bravo decals afterwards! I’ve included a few before and after pictures below:

[FastTex]

9 hours ago, Davidv said:

Between the paint (AF-400) and other supplies it probably cost around $250 and that would have been enough paint to touch up the entire plane.  I just did the tail sections.  The downside is that the finish isn’t as glossy as the original paint but unless you’re looking under a shop light it’s tough to tell.  Is it perfect or as good as a paint shop? No way.  However, the color matched extremely well from Finishmasters and the “brighter” leading edges below are mostly from the light outside the hangar.  @jerrodmonaghan was kind enough to help me with the job as well as applying some bravo decals afterwards! I’ve included a few before and after pictures below:

 

Great! Can you describe the process? Did you use primer? If yes, what type? Did you wet-sandpaper before painting, or? I have the same paint ready to use.

Thanks!

[jetdriven]

there is also an Alodine pen.  no wipe off. let it dry, then  coat over it

 

[Davidv]

38 minutes ago, FastTex said:

Great! Can you describe the process? Did you use primer? If yes, what type? Did you wet-sandpaper before painting, or? I have the same paint ready to use.

Thanks!

I’ll start off with an @carusoam like disclaimer and say that I’m by no means an expert but here is what Jerrod and I did:

1. sand down to bare metal around the areas that we were painting in order to get smooth transitions without ridging

2. Spray primer that was recommended by finish masters based on the paint and color (this was gray). 

3. If you use the high quality AF-400 paint you’ll have to mix it with activator at the prescribed portions.  
 

4.  We used a paint gun very similar to the harbor freight one above and sprayed very lightly (you can add more but not subtract.  If I had to do it all over again, I may have taped off the area but there are differing views on this. Yes, you may get a slight color line but without tape you’ll be spraying tiny particles further back on the elevator that you’ll have to sand out later and may mask your original clear coat.  
 

5.  Let dry for several days and then wet sand using rough to fine sand paper.

6. Buff and wax 

Again, not a painter, just a PPL and please consult someone who knows what they are doing before working on your plane! :).

[RLCarter]

2 minutes ago, Davidv said:

4.  We used a paint gun very similar to the harbor freight one above and sprayed very lightly (you can add more but not subtract.  

6. Buff and wax 

Too heavy of a coat is very common and will chip easier, nothing wrong with a cut and buff once dry but I would hold off on waxing, waxing seals the paint and won't allow the solvents to vent. Trapping the solvent causes tiny air bubbles in the paint (solvent popping). Rolling the edge of the tape will help with the hard line, making it easier the blend in

[FastTex]

2 hours ago, RLCarter said:

Too heavy of a coat is very common and will chip easier, nothing wrong with a cut and buff once dry but I would hold off on waxing, waxing seals the paint and won't allow the solvents to vent. Trapping the solvent causes tiny air bubbles in the paint (solvent popping). Rolling the edge of the tape will help with the hard line, making it easier the blend in

When would you wax? Are you implying it is not needed?

[RLCarter]

4 hours ago, FastTex said:

When would you wax? Are you implying it is not needed?

Depends on temp (time of year), generally I would wait 60 to 90 days, then Wax away. 

[ArtVandelay]

Too heavy of a coat is very common and will chip easier, nothing wrong with a cut and buff once dry but I would hold off on waxing, waxing seals the paint and won't allow the solvents to vent. Trapping the solvent causes tiny air bubbles in the paint (solvent popping). Rolling the edge of the tape will help with the hard line, making it easier the blend in

What is “rolling the edge of the tape with the hard line”?


Tom

[RLCarter]

5 hours ago, ArtVandelay said:

What is “rolling the edge of the tape with the hard line”?

instead of sticking the tape down fully, leave the edge that will be painted loose and rolled back, this gets rid of the hard line from the tape, if you shoot too much paint or get too close to the tape it will leave a hard line even with this method, blending in also helps if to color isnt spot on perfect

[milotron]

Hi, sorry to resurrect this old post, but I am undertaking some touchups with the advice within.

I see that primer comes in zinc phosphate and zinc chromate. Which one do I use?

thanks,

[EricJ]

3 hours ago, milotron said:

Hi, sorry to resurrect this old post, but I am undertaking some touchups with the advice within.

I see that primer comes in zinc phosphate and zinc chromate. Which one do I use?

thanks,

Whichever you can get.    Zinc chromate is environmentally undesirable so is not sold/marketed as much.   Zinc phosphate is the presumed replacement for zinc chromate.    Either works.

[milotron]

4 minutes ago, EricJ said:

Whichever you can get.    Zinc chromate is environmentally undesirable so is not sold/marketed as much.   Zinc phosphate is the presumed replacement for zinc chromate.    Either works.

Thanks, how would the previously mentioned alodine pen come in to this? Is this a prep for the primer or an alternative?

 

Thanks for the help.

[EricJ]

14 minutes ago, milotron said:

Thanks, how would the previously mentioned alodine pen come in to this? Is this a prep for the primer or an alternative?

 

Thanks for the help.

Alodine, which is now Bonderite, is a chemical conversion coating that goes on bare aluminum, as in fresh bare metal, prior to priming or painting.   AC 43.13 has some discussion of the general processes (using older names , like alodine), in Section 6, if you want to wade through that.

[jetdriven]

Prekote works just as well just scrub it on with a red scotch Brite, and then you rinse it off with water and then dry it and then you paint primer over that

[MikeOH]

39 minutes ago, jetdriven said:

Prekote works just as well just scrub it on with a red scotch Brite, and then you rinse it off with water and then dry it and then you paint primer over that

@jetdrivenWhen the term 'bare metal' is used in the present context of preparing aluminum skins for painting does that mean aluminum is just showing, or that it has been sanded/scrubbed?  It was my understanding, perhaps incorrect, that the aluminum skins are Alclad which forms a natural protective oxide layer.  If so, then I would think you need to sand that off and then alodine/Prekote before prime and paint?

Educate me, please.

[jetdriven]

No, you want to preserve as much of the Alclad as possible because the underlying 2024 is very reactive. There’s a certain shop in Arkansas that scuff sounds all the airplanes to get the paint to stick better but what they’re doing is removing the Alclad  and after about five years filiform corrosion covers the entire airplane.

So prekote is an environmentally friendly substance  that passivates surface, so you basically use the scotch brite  to knock the surface protective corrosion layer off of it and the prekote is a non-reactive layer then you put primer over that.

[MikeOH]

14 minutes ago, jetdriven said:

No, you want to preserve as much of the Alclad as possible because the underlying 2024 is very reactive. There’s a certain shop in Arkansas that scuff sounds all the airplanes to get the paint to stick better but what they’re doing is removing the Alclad  and after about five years filiform corrosion covers the entire airplane.

So prekote is an environmentally friendly substance  that passivates surface, so you basically use the scotch brite  to knock the surface protective corrosion layer off of it and the prekote is a non-reactive layer then you put primer over that.

@jetdriven

Thanks, but I'm still a little confused.  Are you saying that Alodine/Prekote will adhere properly directly to unprepared Alclad, which will have a highly oxidized layer of aluminum (Al2O3), by design?  Or, are you saying to remove that aluminum oxide with scotch brite vs. sandpaper before applying the Alodine/Prekote?

[jetdriven]

5 minutes ago, MikeOH said:

@jetdriven

Thanks, but I'm still a little confused.  Are you saying that Alodine/Prekote will adhere properly directly to unprepared Alclad, which will have a highly oxidized layer of aluminum (Al2O3), by design?  Or, are you saying to remove that aluminum oxide with scotch brite vs. sandpaper before applying the Alodine/Prekote?

The Alclad  still looks shiny but it does have a very thin layer that you can’t see of corrosion that protects it. I’m not sure of the exact interaction but I would just follow the prekote directions which says to scrub into a lather with a scotchbrote, rinse, dry.  then apply primer. Obviously you want to take sandpaper and feather the edge of any chipped paint around the area so that it blends well. Just go easy on the Alclad.  It’s very thin. 

[BobbyH]

6 minutes ago, jetdriven said:

The Alclad  still looks shiny but it does have a very thin layer that you can’t see of corrosion that protects it. I’m not sure of the exact interaction but I would just follow the prekote directions which says to scrub into a lather with a scotchbrote, rinse, dry.

Hopefully this may help.  Alclad is manufactured by placing a very thin layer of almost pure aluminum (corrosion resistant) on the aluminum alloy (which is stronger).  The pure aluminum has a natural oxide layer on it's surface that helps with the corrosion resistance.  The art of it is to remove imperfections/dirt/old paint etc. while not removing the pure aluminum protection layer.  It is nearly impossible to get off all the old paint or finish without touching the pure aluminum layer.  Not to mention other scratches already present.  Therefore once prepared for finishing, the Alodine/Prekote helps establish an oxide layer on the aluminum and improves bonding of the primer.  Without the Alodine/Prekote it is easy to get corrosion on the parts in a few years.  A good primer with either the phosphate or zinc chromate also help with the corrosion protection.