Stains! help - Stains on concrete

[smobb]

Hi guys,

Common problem i'm sure but i've had a complete disaster with some concrete stains and are quite, quite bad.

I've very nearly finished a big build. i've cast concrete steps and slabs throughout. The last element to go in as an oak structure at the back of the garden (this should have gone in first in retrospect!) we sheeted up to catch any sawdust etc and made a work station under a pergola.

HOWEVER a windy day sanding and planing the sawdust has seemingly got everywhere. cue soem rain there's tannin stains everywhere, especially in places where the dust has gathered its really bad.

I'm hoping there's some miraculous solution to this problem. i'm reading about bleach or oxylic acid. if anyone has any wisdom on this please share!

[RAPressureWashing]

White concrete? if yes then either a 3:1 hypo (Bleach) mix or the Oxalic Acid will be fine, Oxalic would be my first choice, you can get it ready mixed etc, the product you need is Net-Trol from Owatrol. You can buy direct from them, only thing to be careful of is, it can whiten the concrete so you may have to clean the whole lot to balance it up. There is a hypo mix solution on the stains page on the main site, it's the berries one you are looking for.

[smobb]

Cheers mate, yep it is white cement. Netrol Ordered! Thanks a lot

[smobb]

I've given the Netrol a go (couldn't find the specific 'berries' one you mentioned though) worked a bit but not as good as i hoped. tried Oxylic acid too, i mixed in crystal form to what i think was a strong mix, left it on there, scrubbed it many times, cleaned up ok on an area that wasn't too bad but not going back to white. maybe i'm hoping for too much but doesn't bode well for the worse areas.

just wondering what your process would be if you were to clean something like this? not necessarily just tannins but a lot of dirt etc by this time now to, it's all a bit of a mess. Was all in great condition not long ago so stains haven't been on there long, just seem to be IN it now and have lost the whiteness.

Thanks for anymore help you can send my way.

[RAPressureWashing]

Net-Trol is Oxalic acid, can you post a photo, so I can see the condition of the paving etc?

[smobb]

just managed to get some pics today. wood working was continuous so just left as it was but looking to tackle it end of this week before rain hits.

However, i'm struggling to figure out how to post a picture? it's just asking me for a URL. Any ideas?? sorry, i may be being missing something obvious but really need some more advice on this, do you have an email i could send to?

Cheers, Steve.

[RAPressureWashing]

Yes email them over to me, email address is in my signature below.