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Hypo Strength for..

Carts69

Active member
Messages
435
Location
Dorset
Pressure washed a natural stone patio today, loads of black lichen spots remains.

any advice on what strength mix of 15% hypo will be effective, will a 50/50 mix be ok to use or can I go bit weaker?

 
How do you apply it - I use a electric sprayer which i find does not use loads,  i can then concentrate it on the bad bits and no over run onto other areas

 
Last edited by a moderator:
How do you apply it - I use a electric sprayer which i find does not use loads,  i can then concentrate it on the bad bits and no over run onto other areas
Ive only used it once before, I’ve made up a trolley system with a chemical resistant pump, it’s fully controllable but think last time I had it pumping out too much as I seemed to get through it pretty quick

 
Depending on the severity of the black spots we never use more than 50/50 usually 4-1 will kill it then pressurewash it off never had a problem removing it , what pressurewasher Do you have ? 

 
The best way I found cleaning sandstone is this. Spray whole area with water from a hose so that its soaking wet. Then spray the hypo on and try and get it to stick on bad areas. 45mins later PW whole area. Then inspect area and apply hypo to stubborn spots, neat on black spots. Wait another 30mins and PW off.

 
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