Paint Chip Prep/Prime/Paint Repairs

[Flymac]

I'm sure I'm making this far more complicated than I need to for the simple tasks I'd like to achieve, but I'm confused on all of the different prep techniques, cleaners, alodines, self etch primers, regular primers, epoxy,urethane, etc.  Have spent hours searching around the web and youtube but surprisingly havnt felt like I've found some nice clear videos on repair techniques and selection of chemicals.

I'd like to try repairing some of the common paint defects:

-chips/nicks on the wings, around inspection panels, including the SS screws with paint stripped away...so mixture of bare aluminum surfaces and SS screws

-chips/nicks on landing gear

I have access to a small airbrush and original paint(polyurethane 2k).  Confused on the prep/primers, sanding/blending into surround paint, filling in the lower level of the chip area, etc.

In a fully new paint job after stripping a plane, seems general process is

1. fully clean/degrease the surfaces...products?
2. Alumiprep 33 or similar
3. Alodine 1201 or similar
4. Primer..either Epoxy or Urethane? Seems different primers only accept certain topcoat types?
5. Top coat

 

For chips/nicks...again I'm probably making this too complicated, ha!  Is it simpler where you can really just:

1. clean/degrease surface...what do you like to use?
2. self etch primer...products? just a general zinc chromate primer that will accept polyurethane 2k top coat?
3. Urethane or Epoxy primer...and can be a hi-rise/fill or not to raise chip to good paint level?

How do I prep the surrounding paint edges? Sand with X Grit? Do you prime over the good paint alittle?

Prepping the aluminum skin vs SS screws?

Many question I know, sorry...still searching the internet thought I would have found better videos...a class would be awesome! 

[DXB]

Thanks for posting... following.  I have a few small areas I'd like to fix, possibly on my own, in a 12 year old Imron paint job that is otherwise in outstanding condition.

[carusoam]

I did my own chip and minor surface corrosion while working with my mechanic at annual.  This was on the original paint for a 65C. Spray can of aluminum surface treatment and a can of body shop paint.

When it comes to fixes to the O's updated paint, it goes to Reese Brothers in NJ who make things go unnoticeable...

Dev, check in with Reese... http://kdaviation.com/about-us/

Best regards,

-a-

Edited February 12, 2017 by carusoam

[Greg_D]

I'm definitely interested in this.  There are some spots around the air intakes on my cowling that need touching up.  I'm thinking about using an airbrush or Preval can on those after some light sanding.  The spots on the left wing near the tips are what worry me.  The red and white paint overlap underneath one of those chips.  I'm not sure how to handle that area.

I also need to do something with the exhaust pipe fairings.  I'm thinking of lining them with some heat reflective material on the inside to stop the paint and fiberglass from getting too hot and developing blemishes.

[milotron]

1 hour ago, Greg_D said:

 

I also need to do something with the exhaust pipe fairings.  I'm thinking of lining them with some heat reflective material on the inside to stop the paint and fiberglass from getting too hot and developing blemishes.

^^

This.  I am sure that the lower cowl of my K is supposed to have something in place to prevent the turbo from cooking the paint off, but the paint is bubbled off near the hot side of the turbo. I'd be interested about this process as well as the touch up process near around the cowl. All good stuff.

 My paint overall is pretty decent, but some worn/chipped parts that could use a little love. At least I have some Pratt and Lambert paint codes from 1990 to try and match. 27 year old paint is pretty good!

[RLCarter]

Repairing damaged areas of paint is actually harder than just painting. If you haven't ever painted before I wouldn't practice or learn on your aircraft, 

[jetdriven]

Easier than etch and alodine (for small touch ups, chips, etc) is use an etching primer such as axalta variprime. Then brush on catalyzed urethane paint, make it high. Then wet sand with 800-1000-2000 and hand buff to a shine. The repairs will disappear if you used a computer scanner to match the paint. 

[thinwing]

Good advice..or if the chip is small..1 mm or so forget the primer and place a drop of catalyse plus paint on chip and wait 2 weeks..than tape off and wet sand 400 / 600 wet ,use lots of water and sand even.Finish with 1500 /headlight restore paste/ white polish compound 3m.

[Flymac]

Great to see the interest of a few people also looking for guidance!  And thanks for some of the tips so far...Jetdriven I had to look up "catalyzed" urethane to understand if that was something special there, but I seem to understand now:

1. 1K Paints: No hardener, catalyst or activator required, single component, Air Dry
2. 2K Paints: Requires a hraderner, catalyst or activator....I know this is the paint on my plane, and seems the common choice
3. Single Stage: Does not require clear coat...I think this would be all the aircraft paints seeing its not common we clear coat
4. Two Stage: Requires clear coat

So as an example I find confusing, or where it seems all primers can't just be used as primers before paint, Jetdriven I looked up the Variprime you mentioned, but right on their instruction/application sheet was:

"Tips for Success For optimum holdout and performance, VariPrime® 615S™ Self-Etching Primer must always be primed or sealed prior to topcoat application."

So its a primer...but they still recommend another primer!  Thats what I was finding on some of the commonly available primers say from spruce or so that yes their a self etching, zinc chromate primer to protect the metal, but say not to apply the urethane paints right over them, ie made just for interior surfaces and such.

So theres

1. self etching primers really just meant for protection of the metals, but not intended(or best) to be top coated like exterior painting
   1. or have to follow up with a 2nd primer meant to accept paint better
2. maybe some self etching primers that are meant to matched with certain paint types as specified? Examples/Brands people like?

The more sample brands spray cans/small bottles that can be used for air brushes would be great to hear!

[Yetti]

Watching for proper technique.   Did notice this   

[jetdriven]

I wouldn't prime the whole plane with variprime then topcoat it, but shops around here do that and it holds up. For chips and small spot repairs it's fine.  

Specifically I usually use Nason Full-thane urethane 2k paint and the catalyst that goes with it. Don't use thinner to brush it on or spot spray it with an airbrush. It goes on thicker, then u can sand it and blend it in really good. 

[RobertGary1]

You guys get fancy. . Etch, prime with spray can and paint with spray can. 

Never sand as you'll remove the protection from the factory  

-Robert

[carusoam]

Never sand down to the aluminum surface....

See Alclad for more details on why this can be bad.

Best regards,

-a-

[jetdriven]

If you need to remove something or to scuff for better adhesion, use a red scotchbrite pad. Used gently this won't breach the alclad. Remember this layer is only like .0003 thick. 

Edited February 18, 2017 by jetdriven