TheSamba.com :: View topic - Removing old paint...treating rust...sealing...

Wed Feb 08, 2012 11:28 pm

Ola,

My apologies for the loooong post.

I am busy cleaning up an old bus of mine and have run into two problems...

1. There was fairly substantial tar spray (I am assuming it was tar as it was the most logical thing and seemed to fit the profile) along the RHS sill. Based on a modern VW we had 'de-tarred' at a specialist car place last year, I used paint thinners to remove the spray.

The paint is now covered in a yellow 'film'.

Mineral Turpentine has proved to remove the most of the lighter areas of yellow, but the majority of the area is still very yellow.

Have I done irreparable damage or is there something else I can try to remove the yellowing?

2. Both cab doors had signwriting on them. The PO painted over the damaged areas and over the signwriting with a very sh*tty paint and no prep'. The RHS 'writing was very bad, so I polished it off entirely. I've removed most of the this nasty paint with acetone.

If I look up at the door, I can clearly see three lines of 'writing, which I would love to preserve, if possible. If I hit it with the acetone, which is harsh, it will no doubt take all of it off. How can I preserve the 'writing but remove the very fine layer of outer paint?

3. There is a fair amount of rust on this bus, nothing substantial, but still. I don't have the funds to repaint it now nor do I want to respray it. I have read that I can 'treat' the rust and stop it with phosphoric acid. Is this true, and if so, where can I purchase it? A chemist? Will this affect the metal when it does eventually get painted?

4. Sealing in the patina...I've been getting a lot of mixed information on this. The prominent suggestion has been to cover the paint with linseed oil, which sounds rather odd to me. Is this correct? Any other suggestions, please?

I don't necessarily have access to the same brands that you do, so if possible, please let me know what substances, etc. you use rather than POR-15 this or 'wax-oil that'.

Many thanks and kind regards,

Nic

Thu Feb 09, 2012 10:33 am

Sounds like you are ready to buff out/polish/wax the paint. Thomas @ folksWerks in Beaverton, OR just posted some before/after pics of an original paint Ghia he just polished out/detailed on facebook! 8)

Thu Feb 09, 2012 8:41 pm

The acid will definitely get rid of your surface rust problems, just make sure you dry and clean it well.

If you start polishing over the writing you'd like to preserve you're going to be disappointed.

Thu Feb 09, 2012 9:56 pm

Thetinwizard wrote: The acid will definitely get rid of your surface rust problems, just make sure you dry and clean it well.

If you start polishing over the writing you'd like to preserve you're going to be disappointed.

Is the phosphoric acid just brushed on and wiped clean with water, or what?

The writing it currently covered with a fine layer of paint, so all I can see are the slightly-raised letters. I haven't yet figured out a way to remove just the top layer. :/

Thanks for the advice, chaps.

Thu Feb 09, 2012 10:31 pm

#1. Water is your enemy.
#2. Take a piece of red Scotchbrite about 3" x 3"
#3. Put 10 to 15 drops of Phosphoric / alcohol mixture on Scotchbrite (enough to cover small area).
#4. Scrub rusted area with medium pressure using circular motions over the rusted areas for a few minutes.
#5. Leave wet for 5 minutes
#6. Take your wet scotch bright and scrub the area again for a few more minutes.
#7. Wipe dry with paper towels, and polish clean with clean towels until slick.
#8. Now wipe it down with acryliclean, or pre-cleano, and let it sit for 5 minutes.

Note: Do not touch the the cleaned metal surface with your bare hands.

#9. Gently scotchbrite, with a fresh, dry, clean piece
#10. Blow off your dust.
#11. Wipe off last of dust with towel.
#12. Spray catalyzed epoxy primer to provide adhesion and seal.
#13. 30 minutes later apply your catalyzed urethane sanding primer / surfacing primer.

These steps will provide you with a surface you can wet or dry sand before applying color coat.

You can purchase a very weak solution from PPG products.

Remember, private, water is the enemy!

Thu Feb 09, 2012 10:39 pm

Dang! Now that's detailed info'. :D

I'll be printing and rereading this for the duration of the weekend...

I'll have to do some shopping around to find local variants of some of those.

Thanks, ttw. Much appreciated!