Rust Measles

[Air-Cooled Head]

I’m pulling an old project out of deep storage and putting it on the front burner.
The car was sand blasted and primered to prevent flash rusting. Looks like repairs were made on the fenders, and then rattle-canned.
10 years later, the fenders appear to have developed “Rust Measles”. Little spots/pits of rust. Lots of ‘em.
So now I’m taking it down to bare metal to prep for paint. Problem is, while the rest of the fender is shiney, the “measles” are now little pits of black.

My question is how do deal with these? Someone suggested sand-blasting again, but I REALLY don’t want to go there. That means paying to have the car blasted, repaired and primered, again.

Is there something I can treat these spots with before etch primer?

Suggestions please!
_________________
Everything known to man has been written.
Readers are Leaders!

[BBSquarebackChick]

I would just buckle down and either pay to have it done or do it yourself,better safe then sorry then to try and do something half ass.
_________________
Its not just a VW!!!!Its Family:)

[74vwbaja]

the only way to fix it right is to strip it again

[Air-Cooled Head]

Ha Ha! Around 7 years later, I’m reviving my old thread.

Same situation, different car. After sitting under a car cover for years, I’ve got “rust measles” all over the car, as seen in these pictures.

So, what would you do to cure the measles?
The simple answer is “re-spray”. But I don’t want to go that route because, altho you can't tell in the pictures:
1) Its all OG paint, and
2) Has a wonderful patina, and
3) Has to original fender beading which cannot be replaced (except by black)

I have some ideas, but would like the input of my knowledgeable Sambanista brethren.
_________________
Everything known to man has been written.
Readers are Leaders!

[Mike Fisher]

Lemon Juice will dissolve rust and is pretty gentle as an initial treatment.
_________________
https://imgur.com/user/FisherSquareback/posts
69 FI/AT square Daily Driver
66 sunroof,67,70,71,71,71AT,72,72AT,73 Parts
two 57 oval ragtops sold
'68 Karmann Ghia sold

Society is like stew. If you don't keep it stirred up you end up with a lot of scum on the top! - Russ_Wolfe/Edward Abbey

[W1K1]

The bad part about those spots is on the outside it can be a 1/8" spot but under the paint it will be the size of a quarter on the sheet metal. BTDT
_________________
http://www.thesamba.com/vw/archives/manuals/jim_martin_engine_build.php

1973 super
1965 squareback 1500E
1971 bay window westy- subi swap

[Mike Fisher]

After lemon juice use phosphoric acid & finally good wax.
_________________
https://imgur.com/user/FisherSquareback/posts
69 FI/AT square Daily Driver
66 sunroof,67,70,71,71,71AT,72,72AT,73 Parts
two 57 oval ragtops sold
'68 Karmann Ghia sold

Society is like stew. If you don't keep it stirred up you end up with a lot of scum on the top! - Russ_Wolfe/Edward Abbey

[raygreenwood]

It does not matter what you do.

The rust measles....meaning rust spots anywhere means that the paint is porous. It means that water has gotten to metal.

Unfortunately rust is not just vertical. It spreads horizontally......even if its only a few microns thick it will keep growing. Unless you can strip it...even with an acid...from all sides.....you will never get it all. Recoating with anything on top of that....will make it 100 times worse down the line.

As for OG paint. ...who cares.
Its paint. Lovely and historic though it may be.....what is more important....metal or paint? Which can be replaced.....metal or paint?

I am more impressed with OG metal with no rust than I am with any paint. And patina....dont get me started. Ray

[Air-Cooled Head]

[Air-Cooled Head]

Well, after months of putting it off, I finally dove into my rust measles problem.

And made a few “discoveries”.

First, the car isn’t as “accident free” as I’d thought. There is no evidence of a previous repair (No creases, hammered out wrinkles visible from inside trunk), hood & fenders look like they’ve never been removed, all stickers present. But I found quite a bit of filler in the hood, I finally found a small crease, under/beside the hood emblem. Repair would have required removal of the latch mount, so they just covered it w/ filler.

When I say quite a bit of filler, I mean A LOT of filler.
After quite a bit of work, I found this;

MORE rust spots!
Look closely. Those spots are rust spots that didn’t make it to the surface (yet).

This is when I realized/understood where the blisters came from: Pinholes in the filler.
Whomever did the previous filler work, left a lot of pinholes. Over time the paint absorbed enough moisture to allow the metal underneath to start to rust. Leaving it under a car cover for a couple of years must have provided the perfect conditions for the rusting to accelerate, with some spots eventually bursting onto the surface.

So now, I’m taking most of the hood down to bare metal. This oughta be fun. (NOT!)
Fortunately, the fenders are not nearly as bad.
_________________
Everything known to man has been written.
Readers are Leaders!

[wcfvw69]

I hate rust.. I just went thru straightening out my front bumper on my 70' bus. It had been poorly repaired. They spread filler right over the dent, rust and then, the original paint before applying a cheap coat of paint over it.

What was surprising to me was when I got to the original paint. As some of the other posters already stated, you could see clearly where there was a rust spot from a rock chip on the original paint. The rust spread underneath the original paint a further 1/2" all the way around the little knick..

It was a great reminder to ALWAYS use touch up paint on rock chips going forward..
_________________
Contact me at [email protected]
Follow me on instagram @sparxwerksllc

Decades of VW and VW parts restoration experience.
The Samba member since 2004.

**Now rebuilding throttle bodies for VW's and Porsche's**
**Restored German Bosch distributors for sale or I can restore yours**
**Restored German Pierburg fuel pumps for sale or I can restore yours**
**Restored Porsche fuel pumps or I can restore yours**
**Restored Porsche distributors or I can restore yours**

[Bobnotch]