[craigR]

How on earth, without rubbing, scraping or pressure washing them off can you get an instant result removing white lichen.
Biocide .. still waiting for any noticeable results  2 months in and Sh @  4%  {3:1} doesn;t touch it.
Any advice would be much appreciated.

Thanks.

[Splash & dash]

How on earth, without rubbing, scraping or pressure washing them off can you get an instant result removing white lichen.
Biocide .. still waiting for any noticeable results  2 months in and Sh @  4%  {3:1} doesn;t touch it.
Any advice would be much appreciated.

Thanks.

Simple answer us you cannot

[Smudger]

some lichens form a shell - applying biocide or hypo - even at full strength will be unlikely to remove or kill it - you need to pressure wash  with turbo nozzle to split/crack the shell - this allows hypo to get into the lichen and dissolve  it

Darran

[craigR]

Thanks Darren,
Would you pressure wash the whole roof in this way or just the lichen spots then apply soft wash to the whole roof.
would scraping not be kinder on concrete tiles or a lower pressure lance perhaps and once the lichen surface has been broken and sh applied does it dissolve and disappear quickly or take weeks and months to weather away.

Thanks

[Smudger]

I really don't get the kind to tiles thing - go and get a few and blast the things - its concrete are you really expecting them to explode ??  yet people are willing to scrape metal objects over them that dig in and scratch the surface .....

not I have that off me chest ....

I pressure wash the entire roof - turbo nozzle for clay and concrete and either 15/20 deg nozzle for slate/tin/other
older tiles ( pre - 60's I will reduce the pressure down by about a third ) - all roofs are them hypo'd all over

HTH

Darran

[craigR]

Full and complete answer.
Thanks Darren.

Craig