Black limestone patio cleaning and sealing - Looking for information on cleaning and

[1964johnr]

Purchased Black limestone flags and laid a 30m2 patio on 50mm of cement, then read about the difficulties associated with this very finicky material. It's finished and pointed with a dry mix 4:1 of sharp sand and cement. As experts will already know, this stone arrives with white marks when delivered and when laying is quite difficult to keep clean of cement staines. I have white patches and think it is a mixture of cement and perhaps effluessence (probably spelt wrong). Realising that this stone is a bit of a nightmare for the average DIY enthusuast, I have steered clear of any acid cleaning product having viewed some results on this web site. I tried a few things on a spare flag. Hot water and a little washing up liquid worked to an extent, but not good enough. Diluted bleach did the same. Best results so far have been with vinegar applied neat, scrubbed with an abrasive pad and then thoroughly washed with the hose. Each time I tried something I waited a couple of days to see if there was any reaction. So if possible I would like an expert to let me know of any cleaning tips which will remove the white stains and not destroy the stones and also when that's done, any advice about the best sealer/colour restorer to use on black limestone and how long to wait before sealing. Thanks.

[RAPressureWashing]

Johnr

If you've only just laid the patio, (last couple of weeks) I'd say leave it until it has been down for 6 weeks minimum, If there is very little mortar staining this can be got off with hand-pads & a chemical, but to do 30 square metres by hand is going to be a pain ideally you want a rotary cleaner.
I know you want it Black straight away, but you could do no worse then leave it for this year, let the winter through it's worst at it, then do a big clean & seal next year?
Re sealers, I use a lot of Aqua-Mix Enrich & Seal, very good can be a pain to use though, another I have just started using is Miracle 511 Enhance & Seal and is applied very much like Liftofin so a bit more forgiving if you are not used to sealing.
Both the above are Colour Enhancing Impregnating Sealers which you need for Limestone. Re the "White" scratches the colour enhancing part of the sealer will take care of this.
There are other "sealers" out there, so don't go for a cheap one.

[1964johnr]

Thanks for the info Roger. I will take your advice and leave it over the winter and clean and seal in the spring. I have completed a lot of research and realised that colour enhancing and impregnating sealers are the best bet. Aqua mix Enrich & seal is on my short list, but you seem to be suggesting that might be a little tricky. Can you explain why please. I also had a couple more on my short list. Romex colour seal and Dry Treat Enhance Plus were two of them. I called up a supplier of Weiss FT Plus, but was told that because I laid the flags on cement, it might not be appropriate. I will also look at the Miracle 511 Enhance and Seal which you seem to be suggesting might be a good bet for a DIY Black Limestone Novice like myself. I can't believe how many horror stories I have come accross on the internet about Black Limestone, even so called professional contractors seem to be able to destroy it with cement staines or brick. cleaning acid or the wrong sealer. I was a little shocked at the price of the good sealers, but I guess quality costs. I'm not sure how to judge the amount of sealer i will need. It seems that most suppliers offer different amounts varying from 1 litre through 4 litres and sometimes up to 10 metres, but most suppliers just say coverage varies depending on the material being sealed. I am guessing that Limestone being very porous will take a lot of sealing. I was thinking of a four litre to cover 30 square metres. What do you think?

[RAPressureWashing]

Thanks for the info Roger. I will take your advice and leave it over the winter and clean and seal in the spring. I have completed a lot of research and realised that colour enhancing and impregnating sealers are the best bet. Aqua mix Enrich & seal is on my short list, but you seem to be suggesting that might be a little tricky. Can you explain why please. I also had a couple more on my short list. Romex colour seal and Dry Treat Enhance Plus were two of them. I called up a supplier of Weiss FT Plus, but was told that because I laid the flags on cement, it might not be appropriate. I will also look at the Miracle 511 Enhance and Seal which you seem to be suggesting might be a good bet for a DIY Black Limestone Novice like myself. I can't believe how many horror stories I have come accross on the internet about Black Limestone, even so called professional contractors seem to be able to destroy it with cement staines or brick. cleaning acid or the wrong sealer. I was a little shocked at the price of the good sealers, but I guess quality costs. I'm not sure how to judge the amount of sealer i will need. It seems that most suppliers offer different amounts varying from 1 litre through 4 litres and sometimes up to 10 metres, but most suppliers just say coverage varies depending on the material being sealed. I am guessing that Limestone being very porous will take a lot of sealing. I was thinking of a four litre to cover 30 square metres. What do you think?

Aqua-Mix is neither solvent or water based it is around 95% solids so leaving any excess on the surface is a no-no, solvents are easier to use, water based ones are easy too but become temperature determined , not to hot and not to cold.
Aqua-mix is a great product but you have to work the sealer into the paving so, it take a bit of practice to get this technic just right, once you get the hang of it, it is easy enough to do.
The 511 behaves very much like Lithofin Stain Stop or the Stain Stop plus, it is a solvent. I using this one at the moment on the paving from hell (Black Limestone that has been totally fu*ked up by the builder who has done a runner as well) once I have it finished I'l post photos etc.
Re other sealers, Dry-Treat is supposed to be very good but I haven't used it to date, Weiss products are ok, in the test's I have done with them, they seem to hold up well, did you speak to Steintec ( Weiss outlet) or just a supplier? if it was a builders merchant then I'd call Steintec direct as most BM's haven't got a clue IMO,
Re the amount of seller if it was the Miracle 511 enhance & seal for 30 square meters then no more then 2 lts for two coats.The thing you have to remember is with any Natural Stone NO acid based cleaners and for the best results impregnating sealer, not Topical or surface sealer.
It really isn't rocket science if you stop and do the research like you are doing. Cheap sealers will say you need gallons of the stuff, decent sealers as mentioned above cost more , but go further, do the job needed and work, but do come with a price tag.

[1964johnr]

Thanks for all of your information and help Roger. It is all extremely usefull and I am sure will help me to obtain a great finished patio when I clean and seal it in the spring.