Any chemists here?

[Donny osmond]

I've run a bit of an experiment, and while you could argue I should've done my research beforehand, we are where we are.

A few years ago we got some beautiful Yorkshire sandstone laid out front, but it's has gone black with mould over the years. Pressure washing doesn't work, it just damages the stone and doesn't touch the mould.

I didn't want to use commercially available patio stone cleaners as they're all desperate for the environment.

So I've got some hydrogen peroxide (3% soln), mixed it with a bit of detergent (biodegradable) and spread it over the stones.

Questions:

Is this actually an environmentally acceptable way of cleaning or am I delusional?

Will the peroxide and detergent react together and somehow neutralise each other?

Will the peroxide kill the moss while leaving the stone alone?

I realise it'll take months to see if it has killed the moss or not, so wondered if the RR collective had any predictions?

[Puja]

I've run a bit of an experiment, and while you could argue I should've done my research beforehand, we are where we are.

A few years ago we got some beautiful Yorkshire sandstone laid out front, but it's has gone black with mould over the years. Pressure washing doesn't work, it just damages the stone and doesn't touch the mould.

I didn't want to use commercially available patio stone cleaners as they're all desperate for the environment.

So I've got some hydrogen peroxide (3% soln), mixed it with a bit of detergent (biodegradable) and spread it over the stones.

Questions:

Is this actually an environmentally acceptable way of cleaning or am I delusional?

Will the peroxide and detergent react together and somehow neutralise each other?

Will the peroxide kill the moss while leaving the stone alone?

I realise it'll take months to see if it has killed the moss or not, so wondered if the RR collective had any predictions?

Peroxide and soap is a classic combo, so that's not a problem as far as I know. My one concern is that I don't think 3% is strong enough to do much other than make the stone damp - I'd've thought you'd need it a chunk more concentrated before it'd touch mould, especially mould that laughs at a pressure-washer.

Puja

[Donny osmond]

I am wondering about that but I can always get a higher concentration and run the experiment again in the spring. I'm very much stumbling around in the dark with this, but the only sensible thought I had was to start gentle and go harder if gentle doesn't work.

[Mellsblue]

Treatment: Find your local, reputable doff system cleaning contractor and save yourself the time.

Cause: I’m assuming it’s a patio? Tell me how you’ve laid it, particularly materials used for bed etc. I work with heritage stone built buildings in Yorkshire for the day job so may be able to advise albeit a patio isn’t in my wheelhouse.

[Donny osmond]

Treatment: Find your local, reputable doff system cleaning contractor and save yourself the time.

Cause: I’m assuming it’s a patio? Tell me how you’ve laid it, particularly materials used for bed etc. I work with heritage stone built buildings in Yorkshire for the day job so may be able to advise albeit a patio isn’t in my wheelhouse.

Some good advice and great questions there Mells, that I'm afraid I can't really answer? I laid it by paying a South African guy cash in hand. I'm pretty sure he didn't bed it in properly as it doesn't seem to drain very well, hence I guess the issue with mould, although it is north facing and quite sheltered so, being Glasgow its pretty much shady and damp all year round anyway, so again that's where the mould is going to be.
You could call it a patio. It's just our front 'garden' (about 5m x 5m) that is now paved and has a couple of planters in it for the tiny bit of gardening we do once a year.

As for paying a local contractor, yes that would be the best way but a) I don't know what product they would use and I want it to be environmentally friendly if poss, b) I'm a tight arse (Scottish innit) and c) I'm nearly 50 and this is exactly the sort of pointless long term project that middle aged men should have on the go that they can talk for hours about on the 2 occasions a year that they get to go to the pub ti meet their mates, so ...

[Mellsblue]

Treatment: Find your local, reputable doff system cleaning contractor and save yourself the time.

Cause: I’m assuming it’s a patio? Tell me how you’ve laid it, particularly materials used for bed etc. I work with heritage stone built buildings in Yorkshire for the day job so may be able to advise albeit a patio isn’t in my wheelhouse.

Some good advice and great questions there Mells, that I'm afraid I can't really answer? I laid it by paying a South African guy cash in hand. I'm pretty sure he didn't bed it in properly as it doesn't seem to drain very well, hence I guess the issue with mould, although it is north facing and quite sheltered so, being Glasgow its pretty much shady and damp all year round anyway, so again that's where the mould is going to be.
You could call it a patio. It's just our front 'garden' (about 5m x 5m) that is now paved and has a couple of planters in it for the tiny bit of gardening we do once a year.

As for paying a local contractor, yes that would be the best way but a) I don't know what product they would use and I want it to be environmentally friendly if poss, b) I'm a tight arse (Scottish innit) and c) I'm nearly 50 and this is exactly the sort of pointless long term project that middle aged men should have on the go that they can talk for hours about on the 2 occasions a year that they get to go to the pub ti meet their mates, so ...

Ha! Paying a dodgy saffa in cash is where your problems start and end.

Re a) that’s why I recommended the Doff cleaning system - there’s no chemicals. I specify it on all the heritage buildings I work with.

[switchskier]

Anyone else see this thread title and get Breaking Bad vibes?