Foam brush marks on aluminiuim

[Greg_T]

One bay of our wash has aluminium sheeting on the lower half of the walls. In 2019 I used an aluminium cleaner called "Ali King", which has phosporic acid, hydroflouric acid and butoxyethanol. It worked very well, and it was nearly 12 months before I felt I needed to use Ali King again. So a few months back I used it again, and this time it appears that our foam brush chemical is reacting somehow and leaving ugly brown / black marks. I've spoken with our chemical supplier and cleaning product supplier, and neither could see a good reason why this might occur.

The foam brush chemical is Lustra 250.

I can't work out why everything was ok back in 2019 with this combination of foam brush chemical and cleaning product, but the same combination of chemicals a year later leaves the marks?

Any ideas would be greatly appreciated. Cheers, Greg

 

[MEP001]

I would bet the marks are from dirt off the cars.

 

[Greg_T]

I would bet the marks are from dirt off the cars.

Unfortunately it appears to be a chemical reaction with the aluminium, rather than dirt build-up. No amount of scrubbing / pressure washing / alkaline cleaner will move it, but it removes easily with the original aluminium acid-based cleaning product.

 

[cooll903]

looks like you have hog hair brushes. bet the acid has finally eaten through the treatment that they have gone under before being but on the brush. maybe try going to a synthetic brush?

 

[Greg_T]

looks like you have hog hair brushes. bet the acid has finally eaten through the treatment that they have gone under before being but on the brush. maybe try going to a synthetic brush?

Thanks, I never considered the hogs hair brush as part of the whole package. I'll change out the brush and see if it helps. Fingers crossed.