DIY Doctor UK DIY Forums

Just pulled up bathroom carpet it had black tiles underneath, these came up easily and now I'm left with a black covering on the concrete floor. Can I just paint over this with concrete paint or do I have to remove it.? The black stuff is only thin and seems hard, I was wondering if it might react to paint on top of it.
Any advice appreciated thanks.

Hi

If you are planning on painting it, ultimately, it is best to remove the remaining residue.

You could paint over it but as you say, depending on what paint you use, as you say, it may react (hard to know without knowing exactly what paint and what the adhesive is). Additionally, by painting onto the remaining adhesive you will be bonding the paint to this and if it becomes loose the paint will come off also.

In terms of removing, there are several options - You can but specialist adhesive removers (should be available from your local DIY store), you can scrape it off using a scraper or hammer and bolster if it’s tough, soften it using a heat gun or wallpaper steamer etc….. Some tips on this can be found in the following project: https://www.diydoctor.org.uk/projects/Removingcork.htm

One thing to be aware of is that heating adhesive can give off harmful fumes so be aware of this and make sure you wear a suitable mask to prevent breathing the fumes in and also keep windows and doors open to allow venting.

Hope this helps

Thank you, The black adhesive is like a hard tar type substance (and possibly oil based) I'm reluctant to use chemicals - so I may try a belt sander on it and see what happens. After this I might try and paint it with a concrete paint but I'm not sure if concrete paint is oil based or water based, as I see it once the black stuff has been thinned down by sanding a good coat of paint should cover it nicely, I shall probably use water based paint so that it 'should not' (he said hopefully) react with the 'black' or what is left of the 'black'. The black residue now is quite thin in places and there is some slightly thicker spots so if I attack this with a belt sander I could be home and hosed. Does this sound like a 'plan'?

Hi

In terms of sanding, it really depends on how hard it is. Normally when you try to sand any type of adhesive, the friction applied to it will heat it and it will become soft, clogging up the sanding belt/sandpaper etc…. so in respect to this it will take quite a while and also a whole load of paper/belts to get through it.

If it is indeed rock hard then you may have some luck with this method but, as said, you may be best using a hammer and bolster (be careful not to damage the existing floor) or heating with a heat gun and using a scraper to remove (need to wear a mask and open windows due to fumes). Once softened, the latter method is normally gets it up quite quick.

In respect to the paint, are you thinking this to be the final finish or are you then covering over it with lino, tiles etc….?

Kind Regards