[Deep Cleaning Solutions]

I went to look at a York stone job the other day. The owner said they were just dirty but having inspected them it looks like most of them have more than just dirt. I first thought it was some kind of DIY varnish on the surface but after digging my nails in, I think it's a thin layer of bitumen. I'm worried this job could become a bit of a quagmire and the bitumen being a nightmare to shift. I have images of it just moving around and not lifting. Am I being too over cautious or it will be easy enough to shift. If it is okay to clean, would it best to use a stripper?

[Kev Martin]

Don't  try and guess!  Explain your concerns to the customer and do a test area first

[Deep Cleaning Solutions]

No guessing here pal!

I am 99% sure it's bitumen after testing thousands of bitumen backed carpet tiles over years.

Regarding testing - I have already mentioned the pitfalls and have told him that I always clean a test area first!
I was not asking for someone to state the obvious 

He is a potential problem customer. I don't get them often but I'm getting the vibes and I'm already 50/50 on doing the job. I was just hoping someone was going to say they have had the same problem in the past and to run a mile 

Tbh, I was just looking to see if anyone had the same issue in the past and if so how did they find it.

[Kev Martin]

I never state the obvious!   This is stone not carpet tiles.  However, that said it may be carpet tile residue?  Or it maybe marley tile residue?  Or it may just be emulsified gunk?   I have had the same problem loads of times in the past and every floor has been different.  So I do what I advised you to do  every time, conduct a test area.  Get it wrong with stone and you will regret it.  Failing that just run pal

[Deep Cleaning Solutions]

He's cancelled now anyway. Called last night. The job was in a shut down pub and said he had a massive barnie with the brewery so he's walked! Probably a lucky escape for me anyway as mentioned and I had bad vibes about a few things on this job!

[maxcampbell]

Too late to be relevant for this one, but we went to have a look at something similar - thick layer of bituminous tile adhesive.

Our next step was going to be getting a sandblaster to quote for cleaning off - didn't fancy the mess made even by just a test patch - (we had monster brushes & solvent stripper in mind) but they, too, pulled out.