Welcome to the UK Window Cleaning Forums

Starting or own a window cleaning business? We're a network of window cleaners sharing advice, tips & experience. Rounds for sale & more. Join us today!

Efflorescence and red Algae removal from render

I think I would advise to softwash it and then a few coats of white paint. There must have been a lot of salt in the mortar maybe coming from the water they used. Even if you did get rid of the surface salt it would just come back through time.
 
If it was brick I'd say brick cleaner / hydrochloric acid. It's a VERY nasty chemical but used correctly is excellent. But I've never tried it on render. You could try a test patch and make sure its thoroughly wet before and don't allow it to dry out on surface.
Do you now if its Weber, K Rend etc? If so, get in touch with them to see what they recommend.
Or you could try dry brushing to draw out the salt and then wiping clean.
White vinegar is another method that is sometimes suggested on reputable sites like inspectapedia and Brick Development Association. It's still acid based but less harsh although I've never tried it myself.
You could even try giving it a vacuum - which is another sometimes recommended option.
If you can draw out all the soluble salt it won't keep coming back unless water is getting in another way?
 
Thanks for your reply guys,

I like the idea of a vinegar application, think I'll try a test patch to see.

It might just be water staining, I've done quite a few sand & cement render cleans with some similar type staining but in much smaller areas.

A good 4% agitated hypo wash would do the trick

cheers
 
Thanks for your reply guys,

I like the idea of a vinegar application, think I'll try a test patch to see.

It might just be water staining, I've done quite a few sand & cement render cleans with some similar type staining but in much smaller areas.

A good 4% agitated hypo wash would do the trick

cheers
Water staining? - like limescale do you mean?
Hypo for the red algae but it won't help with efflorescence or limescale
 

Latest Posts

Back
Top