I did a test sample for a potential customer on an old grey painted block building. The paint is discolored by vehicle exhaust. The building is about 10 years old. I did a test with a strong house wash and no difference. I then did a test with a light degreaser. This cleaned the top layer of paint off. I actually had paint wash on the asphalt I had to rinse off. I just used a soap nozzle to rinse. I took pictures and talked to the customer about the test spots. He doesn't want to repaint the building as it is quite large. The degreaser I used is the same we use on trash area walls all the time. I have never had it pull paint before. I was surprised by the result and there was still paint covering the block. As I haven't seen this happen before I didn't know if there is a more standard chemical that I can use for removing heavy pollutants from painted block? I'm on my iPad or I'd post pics too... Any thoughts would be much appreciated.
Heavily soiled white paint on block?
- Thread starter Jared
- Start date
Diamond Jim
New member
You can jack up the house wash solution with sodium hydroxide or potash flakes until you see it start to work. I ve done some pretty oxidized buildings. Chemsol from eaco chem is pretty good for for this but can get pricy . It has a sodium hydroxide base.
Paul Kassander
New member
The Hydroxides are dissolving a layer of the paint which is why the stains are coming off. Now it may just be the oxidation or it may be a layer of the paint that you are removing it just depends on the quality and condition of the paint. This process however may be your best bet for removing the stains. But remember if the paint is thin or the chemical is too strong you may remove it down to the substrate so be careful. Make sure you let the customer know if you will be cleaning it this way and inform them they may need to repaint some areas if the paint fails or is too thin.