Opinion on if the PWR guy has damaged this Zinc Cladding?


I usually post on WCR but thought I’d reach across! The debut of this issue I wrote about here.



I have a builder asking me about some cladding. There is what appeared to be possibly a white rust or a salt deposit from sea air or a salt from the blockwork but then in the search for answers I sent photographs to some chemical suppliers and they allege this looks like sodium hypo oxidization. There is a powerwasher guy on site using SH in his powerwashing mix.

I do some softwashing myself - but I haven’t seen zinc affected like this before. I don’t use high concentrations. What do you think?

IMHO I’d walk away as quickly as possible (if possible). Life is too short for stuff like that.


That seems to be a consensus but happily I have promised the builder nothing - only that we’d look into it. I thought I might ask him to fund some chemicals and we could test them out because the situation is exotic. My suggestions to date have white vinegar or other weak acid, OneRestore and Sabre 2 - also A1 from Titan Labs.

I’m curious about the cause still - do you reckon it is SH?

Walk away….

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Yes on the SH

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Those other pics you posted show the door hinge rusting, as well as having that white stuff on it. Are you saying the guy just did all this in one day?

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This is a bit of a warning to myself actually too - I’m new to softwashing but I’ve been taking care to rinse the area and using Benzsoftwash products which are the minimal amount of SH compared to some of the purer mixes.

No not at all - the site is about 12 years old and has been derelict since the Celtic Tiger bust - that is why myself and the guy powerwashing are here. I should scan the other houses that aren’t worked over to check if the cladding has the same affect.

My guess is now his mix is too strong or possibly got sprayed on near neat by accident.

This pic leads me to believe the oxidation is from years of exposure to salty air. IMHO A hot mix would have discolored those doors or windows substantially if it was bad enough to do this to the hinges.

I don’t know what that is, because those hinges appear to sit behind the door, protected by wood. I am guessing the even if he sprayed those doors directly, there is no way he would have caused rust and that metallic corrosion in a day or two, unless he is spraying 12.5 directly and not rinsing.

I just found it odd. Go with what the pros are saying. I don’t live in the south, near the ocean, and I don’t do a lot of washing. Metal and salt don’t mix well, in the north all the cars rust from salt.

I had to google celtic bust, interesting.