Tough staining to remove

I have a big job to do for a regula customer on their second property with includes a glass pergola with a few badly stained glass panels (pic attached). I'm looking for advice as to what chemical would remove this straining. I'm trad clean but will be using my phantom trad pole and I have access to water with hose from the exterior tap. 

Thanking you all in advance 

John

mupps said:

I have a big job to do for a regula customer on their second property with includes a glass pergola with a few badly stained glass panels (pic attached). I'm looking for advice as to what chemical would remove this straining. I'm trad clean but will be using my phantom trad pole and I have access to water with hose from the exterior tap. 

Thanking you all in advance 

John

View attachment 17807

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Looks very much like staining from lead work above it.

Many years ago we had a conservatory glass roof clean that was butted up against the wall with lead flashing and the stain had become a lead 'crust.' The lead flashing had stained the glass something chronic. We did our best, but although the glass was clean, the staining never budged. We spent a couple of hours on it (much more time than estimated) and the result was a very unhappy customer. In our case we lost this customer although we still continued to clean his mothers flat which he paid for until she died.

Some have suggested Cillit Bank Lime scale remover (not convinced of this myself), others Bar Keepers Friend and another suggestion was Hob Brite applied with a damp cloth. The problem is that lead staining becomes highly insoluble. Someone else suggested a phosphoric acid cleaner, (some oven cleaners contain this) would dissolve the stain. It would appear that dissolving the lead stain is the problem. The other cleaners are abrasive cutting pastes to cut or grind the stain away. You also have to ensure the surface of the glass is totally clean as any grit will scratch the glass. And obviously if the glass is self cleaning then you run the risk of damaging the surface.

If you are going to get involved, I would buy the cleaner and then try to clean a patch to see if it will work.

Its only once you have done that that you we be able to see if you can do it, give an estimate and see if even the jobs worth doing.

We learnt from that and don't do anything like that these days. We will clean the glass but we can't do anything about the staining. Suggest they call in a specialist or replace the glass roof after removing the lead.

IMHO you are on a path to nowhere if its anything like what we had.

Please let us know how you get on.

Ive got the same on a customers glass kitchen roof, i do an hour a time for £25 and have been using HG from homebase, ive had 3 goes at it so far and its slowly but surely coming off.

Bar keepers friend - mix into a paste and apply/scrub with a 000 grade scourer (like the white Gardiner ones). I’ve used virtually every product available (including hydrochloric acid) and bar keepers friend is the only thing that removes it completely. The pink stuff also works but not as well and it still seemed to leave a ‘shadow’

bar keepers found in Tesco    Sainsburys   £2.50