Block paved area

[Richard Ivy 14]

Hi all,

I was doing a window cleaning job today, and I thought I would bring up the subject of pwing the customer's drive, as well as clean their algae (is that what you in the US call 'mold'?) off their gutters and soffits.

Anyway, on close inspection of their drive, which, like I say is block pavers, I can see four things to have to deal with:

1) The 'ordinary' grime associated with three years wear and tear

2) Some oil marks, quite a lot, from vehicles, including engine oil and steering mechanism oil

3) Rust stains from a builder's skip bing left in situ while some work was being carried out

4) Tyre marks from vehicles as they turned in the drive and have scuffed off tyre rubber

What you think? How would you deal with each of these probs?

I have a 200BAR cold water pw, and 20" whirlaway.

I am presuming that you are familiar with block paving - usually herring-bone shaped.

[Larry B 55]

Mold and algae are 2 different things. Most residential type mold is black while algae is green. They both however are cleaned with the same thing-chlorine bleach.

The black streaks on gutters are cleaned with a butyl based degreaser and is brushed on then rinsed off.

Oil spots are treated with degreasers as well, just spot treat the stains. You will lighten it but most likely not remove all of it as concrete is porous.

Rust is oxalic acid, although you will most likely have to treat the entire area to achieve a uniform look.

Tire marks may come off with just the surface cleaner.

Do a search on here of pavers. I remember some posts in the past and they had before and after pics as well. You need to investigate the pavers closely, be sure they are solid color all the way through. You will also want to do a test spot with the products before you actually spray them all over. You don't want to change the look of them by removing too much color or surface.

[Richard Ivy 14]

Hi Larry

,

Any idea how much coverage a 5l pump-up sprayer of oxalic acid would cover?

[bforbis 14]

Richard,

A 5 L sprayer is about 1.3 US gal. Depending on concetration/ need, I use about 1gal/150 + sf for saturation. It may go a bit further than that, but it is a starting point for calculations