I need to know if blue seal can be applied over asphalt tar coating or does the tar coating have to be removed?
I need an urgent reply, have to get it done in two days from now.
If you meant blue skin, then definitely not. Its only applied onto a smooth surface, to maximize the grip. Blue skin won't stick to oily pored surface of asphalt and even if it will its only temporary and ineffective.
Provided that the surface is clean and very dry, I would have no problem adhering Blueskin to the asphalt damp proofing on the wall. The surface should also be fairly smooth. If there are small holes in the surface, then fill them with a compatible mastic.
To be certain, try a test patch first. My guess is that you will have a very difficult time removing the test patch.
Try to remove the asphalt damp poof layer. If it comes off easily then you will need to remove it all. If the asphalt layer is not well adhered you can not use it as a base. If there is any oiliness to the existing material, then remove it all. I dont expect that you will find it oily.
My guess is that you will have a very difficult time removing the damp proofing, thus making it a good base for your blueskin.
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