Patio dark patches after sealing

[DIYMarky]

Hi all, last summer I throughly cleaned our patio then sealed it with a gloss finish Thomson water sealant (I think it was called). Unfortunately the patio has some unsightly dark patches permanently. Can anyone advise what they are and if anything can be done about them or is it a case of cheap patio flags?

Many thanks.

 

[r896neo]

I would say its a cheap sealer rather than an issue with the flags.

did you let it dry properly before sealing? Looks like moisture trapped under the sealant.

 

[DIYMarky]

Yes I let it dry first, those patches weren't there when I sealed it.

The sealant wasn't cheap it was >£20 for it.

Any ideas how to remedy it or do you think I'm stuck with it?

 

[r896neo]

While it may not have seemed cheap to you, that is one of the bottom end sealants. A proper solvent based paving sealent would be £200 and up for a normal sized patio.

I would guess that the sealant is starting to delaminate away in patches and then water has gotten into the gap. Without removing the sealant (which is a hellish job) your probably stuck with it.

If you really cant live with it post on the paving expert 'brew cabin' forum as there is one sealant expert on there. It will be costly to remove and the chemicals involved dont really make it easy to diy.