# Metal repaint prep, lots of chalk



## straight_lines (Oct 17, 2007)

Have over 10,000 sq ft of metal siding to put a bid in this week on. Metal is really chalky and I wonder what is your methods for best removing it. 

I normally use TSP, and have to bucket scrub with a pole brush to get the chalk off when it is this bad, followed by a good pressure washing. This job would be to labor intensive for that. I didn't take any pics when I looked at it, but rubbing your hand across a small area would pick up so much your hand would be covered.

Basically what chemicals/methods would you use?


----------



## TJ Paint (Jun 18, 2009)

use a good cleaner and pwash.
I would consider using an additive like emulsa-bond from flood, designed to bond to chalky surfaces. Or talk to your rep and see if there is a wash primer or other primer designed for chalk. I've had excellent results with emulsabond. Peel stop is supposed to work for chalk but I've had mixed results.


----------



## Lambrecht (Feb 8, 2010)

Check out a product from wash-safe called painters wash. It will remove all the chalking without scrubbing and leave a nice clean surface.


----------



## straight_lines (Oct 17, 2007)

Do you use painters wash? Says its hydrogen peroxide.


----------



## Lambrecht (Feb 8, 2010)

Yes, I use it all the time. Its main ingredient is sodium percarbonate which is the powder form of hydrogen peroxide. The stuff works great. It will kill all mold/mildew and remove the chalking. You can spray it on with a pump srayer and use a pressure washer on low pressure to rinse. You can get a sample size to try, that is what I did the first time I used it. The best part is that it does not kill the plant life.


----------



## johnpaint (Sep 20, 2008)

Sometimes chalk goes all the way to the primer, but if it's from old oil paint probably not.


----------



## straight_lines (Oct 17, 2007)

Its the original factory finish, probably some uv baked sort so I hope it isn't chalked all the way through. Still don't know what to finish it with either, was thinking an acrylic dtm.


----------



## NCPaint1 (Aug 6, 2009)

Lambrecht said:


> Yes, I use it all the time. Its main ingredient is sodium percarbonate which is the powder form of hydrogen peroxide. The stuff works great. It will kill all mold/mildew and remove the chalking. You can spray it on with a pump srayer and use a pressure washer on low pressure to rinse. You can get a sample size to try, that is what I did the first time I used it. The best part is that it does not kill the plant life.


Thats the same active ingredient in most concentrated wood brighteners. Most need to be diluted. BM's has an up to 8-1 breakdown. Maybe call tech support, tell them what you are doing and that the chemical recommended for washing is sodium percarbonate. Maybe they would give you a different breakdown needed for washing the aluminum.


----------

