[evil genius]

Turned up to the job this morning. Timber decking, around 5 years old, need sealed or painted and never cleaned either by the look of it!

 Usual hypo mix, a good scrub and a very low rinse with the Whirlaway. For some reason it didn't even touch it. Repeated process a few times with not a huge more improvement. Hypo all gone so only choice I had was to nip to DIY store and all I could get my hands on was some swarfega deck Cleaning. This again didn't do a great deal.. Dilution says 10:1 for heavy soiling, I even tryed it neat on a small 100mm square section that was hidden away.
It's better than it was but still half a job and I'm far from happy. The customer was over the moon for some reason but that's not the point, I want to get it to where I'm happy with it.

Anything else I could try?

I'm Hoping roger might be along soon 

[Blast Away]

What was your hypo mix?

I know what you mean, not all timber comes clean as fast as any other. Do you just do hypo and water in your mix? No surfactant?

[Kenny83]

maytbe the hypo was a few week old and weaker? sometimes that happens to me and I do a weak hypo mix and leave it on as the algae is in the wood so needs to soak down into it which could take 24 hours, thats what I find anyway, not an expert on decking though...

[evil genius]

Blastaway,
Was 14% stuff. Started off weak and got down to 1:1, at this point I had used all my hypo.
No surfactants,just hypo and water. What would you recommend?

Kenny,
Does the strength weaken as the chem ages? I would say it was a good 10 weeks old since bought.

Thanks.
Ian

[Kenny83]

Yes evil it does weaken, ask Lee, he knows, i gave him some to take on a job once that I'd had in the garage a month or 2, and he may aswell have used just water lol. and 10 weeks is a long time mate, I think it evaporates out the holes on the drum

[Neil Jones]

What surfactant do you use? Also I used it today but i'm always worried about killing plants, how likely is it?

[evil genius]

You learn something new everyday. I would say that's played a big part in me struggling so much with minimal results then. Thanks.

Blastaway,
What ratio would you use and would be interested to know more about the surfactant used too.
Thanks.
Ian

[Blast Away]

It's deffo lost its strength.

Here's one we did in Wigan a couple of weeks ago.

Amine Oxide is the surfactant. Long name Lauryldimethylamine oxide.





About 5 litres of hypo cleaned that decking. That's £2 worth.

[Blast Away]

I'd like an image of it dry. 

[evil genius]

That's what I was hoping this would turn out like.
Is the surfactant a foaming agent? And what ratio was that mixed at if you don't mind?
Thanks very much.
Ian

[Blast Away]

Yes and it doesn't weaken the hypo. The more water the more foaming. 5l hypo and 5l water and about 300ml of amine.

[Roger Oakley]

Evil,

That is pressure treated deck/wood from the photos, so can and usually has a certain amount of "green" in the wood from the pressure treating process. the other problem is the deck is very close to the floor and the gap's between the boards are really close , so no real air flow, so the deck holds moisture thus giving it the "green effect. The cleaned deck photo looks ok from what I can see, so you can do one of two things, re clean with a hypo mix of 1:1 with a longer dwell time, but this might "bleach" it out to much and if you re-oil/seal the deck can tend to go very Yellow as opposed to the warm pine finish it should be, or you could apply a stripper, then brighten, allow to dry then re-oil.
This way you would have done all that you can do with pressure treated pine, you never get rid of the green that is in the wood naturally, oiling will darker it a bit but it still there, the pain of working with pressure treated wood unfortunately.

[Blast Away]

Well that's something I never knew. Pressure treated. Hmmm, I've had my fair share of meetings with them then.

[Roger Oakley]

Well that's something I never knew. Pressure treated. Hmmm, I've had my fair share of meeting with them then.

The after photo you put up has it, bottom left hand corner 
if they have a slight green tinge to them after cleaning, usually runs in straightish line's along the wood then it can come from the PT process, usually cheaper boards to be honest.

[Roland S]

Do you neutralise the hypo on decking afterwards or is rinsing sufficient?

[Roger Oakley]

Depends on the wood

[Kenny83]

Rog, whats the max dwell time you can leave the 1 to 1 mix on without bleaching the wood? In the past I have done a mild mix and left it on as I leave the job, i have returned to sand some block paving on the same job when dry and it worked, got rid of all the green, can it damage the wood though by leaving it on without rising off?
Thanks

[Roland S]

Just standard softwood decking (redwood or whitewood)

[Matt Gibson]

I used about a 1 to 3 mix on this, just put a squirt of fairy liquid in the mix, get a little bit of foam, but it makes it slippery as ice too. Seems to work well. Have only just started to use the whirlaway on the decks too, i was always scared of marking them with it, but it works a treat and stops all the hypo getting sprayed everywhere when you use the lance.

[Roger Oakley]

Rog, whats the max dwell time you can leave the 1 to 1 mix on without bleaching the wood? In the past I have done a mild mix and left it on as I leave the job, i have returned to sand some block paving on the same job when dry and it worked, got rid of all the green, can it damage the wood though by leaving it on without rising off?
Thanks

The thing is with stronger mix's is you are bleaching the wood just by natural of what hypo is, and the deck can start to look patchy in places if left on to long, a maximum time for me would be 45 mins-1 hour but not letting the deck dry out with the beach on, then really flush it off.
Are you using and additive-surfractont in your mix?

The other thing with leaving hypo on and not flushing is the home-owner walking on it and maybe then walking into there house with shoes on and marking their floor!!!!

Re damage, shouldn't do really if flushed off, there is some debate about damage to cedar using hypo, I have never had a problem with cedar decking using a 3:1 mix so jury is out on that one.

Far better to stick to 3:1 mix then brighten with either ox or citric acid.
Half the secret is keeping the mix ratios the same and evenly covering the surface and keeping dwell times the same if you have to do the deck in sections

Roland
As above, and for hardwoods, ie Ipe Teak etc then yes brighten then wood, you'll get a better surface to work with if you are going to be oiling.