Cleaning / Removing concrete splashing from pots

MisterNick

These pots have been damaged whilst the builders were in.

Can anybody help with the best way of removing please? I haven't tried anything yet, but have wire brushes if necessary. I thought there may be a way of cleaning it off.

Bradden

There a few prducts which could help on the market...

Sika 5L Brick & Patio Cleaner | Lawsons
HG Cement Grout Film Remover (Product 11) 1L | Lawsons

Should be available from a merchant local to you.

FreeBear

Bradden said:

There a few prducts which could help on the market...

Sika 5L Brick & Patio Cleaner | Lawsons
HG Cement Grout Film Remover (Product 11) 1L | Lawsons

Should be available from a merchant local to you.

Be careful when using acids (which both those contain). Test on a discrete spot that will be hidden from view first just in case it eats away at the glaze/finish.

Don't forget to wear stout Marigold type gloves and some eye protection (better still, a full face shield). And what ever you do, do not add water to the acid to dilute it. Always, always add the acid to water.

MisterNick

Thanks for the suggestions Bradden, I thought they looked quite strong and was going to ask whether anybody had used them. I looked at the HG one on their site and they demonstrate using it on a tiled floor.

Thanks FreeBear for the warnings. On the HG website they are suggesting 1:10 dilution for use on glass, so I presume it is fairly powerful stuff. 

stuart45

It's not really strong. Most patio cleaners only contain about 10% hydrochloric acid, which is the main chemical that breaks down cement. I've used much stronger industrial acids on site. Even with those it can take quite a few washes to get rid of thicker pieces. Apart from dangers of strong acid, it also breaks down any cement mortar joints, and any concrete slabs.

MisterNick

stuart45 said:

It's not really strong. Most patio cleaners only contain about 10% hydrochloric acid, which is the main chemical that breaks down cement. I've used much stronger industrial acids on site. Even with those it can take quite a few washes to get rid of thicker pieces. Apart from dangers of strong acid, it also breaks down any cement mortar joints, and any concrete slabs.

Thanks for your input, I'll bear that in mind. The patio is coming up anyway

twopenny

You have fibreglass and stone/clay pots there.

The glazed one I'd be inclined to soak then use a window scraper (the one with a stanley blade) to get some off. No telling how much but the glaze should make it able to be chipped off.

The fibreglass be careful but again it's tough stuff. I'd try the same as it's a more delicate substance.

Surprising what you can do with water/washing up liquid etc.

FreeBear

twopenny said: Surprising what you can do with water/washing up liquid etc.

If it is fresh deposits (no more than a few days old), washing up liquid and a scouring pad may be all that is needed.

Cement needs time to fully harden. 5-7 days for a complete set, and around a month for full strength.

stuart45

There's 3 main phases for concrete or mortar. Initial set, final set and hardening. The initial set and hardening begin as soon as water is added to the mix. The initial set finishes when the mix isn't workable. Often about 30 minutes, depending on the weather, strength of mix etc.
The final set then begins and is normally finished between 12-24 hours. It's finished for example when you can walk on concrete without sinking a bit, but may mark the surface. 
It's estimated that concrete can carry on hardening for a hundred years, but it's tested at 28 days as most of the hardening is done at this point, and for example you couldn't wait a year for a cube test on a bridge, so 28 days is a compromise.