Bleaching grey from Camphor Laurel

I have a fair bit of Camphor Laurel here with a lot of dirty grey through the pale areas. I was wondering if anyone has had any success bleaching the grey out, and if so what bleach is best?

I've tried 'Exit Mould' with very limited success - it makes the grey a little lighter but doesn't go close to removing it. I was going to try 'White King', but a look at the label tells me it's pretty much the same as the 'Exit Mould'.

Maybe hydrogen peroxide?

It's still a bit moist, but the grey is easily visible. Would a second go with the same bleach make a difference?
This was going to be a box top, but I'm not so sure now: -

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Sodium hyperchlorite works pretty well. brush it on liberally in the shade somewhere let it sit for a while then hose it off. It should make the timber as white as bleached driftwood when it dries out.If first time doesn't bleach enough then repeat untill desired result is achieved. Just be carefull to wear rubber gloves, eye and breathing protection. You should be able to get it from an industrial cleaning supply place.

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Originally Posted by artful bodger

Sodium hyperchlorite works pretty well. brush it on liberally in the shade somewhere let it sit for a while then hose it off. It should make the timber as white as bleached driftwood when it dries out.If first time doesn't bleach enough then repeat untill desired result is achieved. Just be carefull to wear rubber gloves, eye and breathing protection. You should be able to get it from an industrial cleaning supply place.

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Thanks for the reply ab. Both 'Exit Mould' and 'White King' are sodium hypochlorite, at 42g/l, so I was on the right track. Probably just a little weak to work quickly. I'll try to find a supplier of a higher concentration.

Meantime, after drying overnight it's looking much better, bordering on acceptable, so I'll give it another go shortly.

I've been pretty much using the method you describe - brushing it on liberally in the area I want to bleach, then letting it stay there for an hour before rinsing off under the tap. I re-brush it on a couple of times during the 1-hour soak to keep it nice and wet.
When rinsing, I also used a nylon brush to scrub the area under running water, to make sure I left no bleach. I was also wondering if a rinse with dilute vinegar afterwards might help to lower the pH a bit nearer to neutral.

I'll brush on another coat or two today, then when dry I'll post a pic of the final result, for anyone else reading this.

The stuff I used was Hunters (brand). Its got 130g/litre of sodium hyperchlorite and 125g/litre of available chlorine.
At the time I did also look into using hydrogen peroxide which could have been purchased from a chemical distributor in an extremely high potency, however I was talked out of using it due to the dangerous nature of it. I was told that if I spilt any onto leather boots they would instantly burst into flames! Heaven only knows what a splash in the eye might do?

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Originally Posted by artful bodger

The stuff I used was Hunters (brand). Its got 130g/litre of sodium hyperchlorite and 125g/litre of available chlorine.
At the time I did also look into using hydrogen peroxide which could have been purchased from a chemical distributor in an extremely high potency, however I was talked out of using it due to the dangerous nature of it. I was told that if I spilt any onto leather boots they would instantly burst into flames! Heaven only knows what a splash in the eye might do?

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And I thought my dogs had a big bone! I'd love to see the cow the one in your pic came from.

130g/l sounds good. I'll see what I can find.

Yeah, usually peroxide is only 3%. I used to use it for sterilising my home brew gear, further diluted 30ml/l. I think the industrial stuff is about 30%. Like you, I think I'll stick to sodium hypochlorite.

Sodium hypochlorite is used in household bleach @ 3-8 % sodium hypochlorite; water treatment @ 10-25%. Good source of affordable sodium hypochlorite @ 12-15% is widely used in pools but be very aware of the concentrations. Do not use “pool shock” products as they have very high concentrations of sodium hypochlorite and far above what is required to bleach timber or safe to use in a hand application.

Sodium hypochlorite gives off chlorine gas and is also very corrosive so not good to store in your workshop with tools. Definitely a no no using metallic containers, stirers etc or mixing with hydrogen peroxide..

Some key phrases from MSDS's

Incompatible with acids , metals , metal salts , peroxides , reducing agents , and ethylene diamine tetraacetic acid . Incompatible with ammonia and ammonium compounds such as amines and ammonium salts.

Causes severe skin burns and eye damage. Do not breathe dust/fume/gas/mist/vapours/spray. Wear overalls, chemical goggles, face shield, elbow-length impervious gloves, splash apron or equivalent chemical impervious outer garment, and rubber boots.

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Originally Posted by Mobyturns

Sodium hypochlorite is used in household bleach @ 3-8 % sodium hypochlorite; water treatment @ 10-25%. Good source of affordable sodium hypochlorite @ 12-15% is widely used in pools but be very aware of the concentrations. Do not use “pool shock” products as they have very high concentrations of sodium hypochlorite and far above what is required to bleach timber or safe to use in a hand application.

Sodium hypochlorite gives off chlorine gas and is also very corrosive so not good to store in your workshop with tools. Definitely a no no using metallic containers, stirers etc or mixing with hydrogen peroxide..

Some key phrases from MSDS's

Incompatible with acids , metals , metal salts , peroxides , reducing agents , and ethylene diamine tetraacetic acid . Incompatible with ammonia and ammonium compounds such as amines and ammonium salts.

Causes severe skin burns and eye damage. Do not breathe dust/fume/gas/mist/vapours/spray. Wear overalls, chemical goggles, face shield, elbow-length impervious gloves, splash apron or equivalent chemical impervious outer garment, and rubber boots.

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:oo::oo::oo: Yeah, looks like a bit of care is in order. Even the household stuff is pretty harsh when undiluted.

I've spent the last few days giving it a coat of bleach then drying it out for a day before applying the next, so the bleach didn't soak into the darker figure.
I couldn't find a local supplier of sodium hypochlorite, so persisted with the Exit Mould.

I didn't manage to completely bleach out the grey, but it's much better. I'll have to make an effort to get some higher concentration sh for next time.

Pics are after one coat on the left and after 4-5 coats on the right. I'm sorry I didn't take one before I started now. It was a fair bit worse.: -

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