Hello everyone thanks in advance. I was trowling on thin set onto hardybacker board but I had a difficult time getting the thin set to stick to the backer board. I had to force the thin set on with the flat side of the trowel but even that did not work easily. Is there something I do not know or is that just the way it is? Thanks again.
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The thinset should be a nice creamy texture, it should stick like crazy to the inside of your bucket and your tools... the hardest mortar you have ever cleaned off. Follow the mix directions on the sack exactly.
It also helps to wipe the Hardi down with a damp sponge right before you place the thinset.
That's a common problem that can easily be remedied by technique. First, vacuum the backer board. Then wipe it down with a good size wet rag to remove the remaining dust. It's ok to leave the board damp.
While the thinset is slaking, wipe the board down again to dampen the surface. Then apply the thinset. Yes, it is normal to use the flat side of the trowel to force the thinset onto the backer board. You often have to work it in several directions, and it will end up in a fairly thin skim coat. Then just add more with whichever side of the trowel works, then finally comb the thinset to final ridges.
If you are setting large tiles, comb all in one direction so air can escape along the troughs. If you swirl it around, you can trap air pockets which will prevent you from being able to push the tile down into the thinset enough to get sufficient contact.
You may have mixed the thinset a little too dry, but be careful not to over wet it, as you'll loose strength if you add more water than proper.
It was either much too thick, or much too thin, or the hardie was very dusty/dirty. When you mix/stir the thinset it forms peaks, like cake icing. They shouyld stand up all by themselves, and mix should not fall off the mixer. It should be a little thinner than peanut butter.
You should spread the thinset all across the hardie with the smooth edge of the trowel, then go back and comb it even.
I'm sorry, I thought you wanted it done the right way.
Dirty board, dry mix.
Clean the board, you'll get a ton of dust off some of it.
I use a squirt bottle to dampen the board before spreading the thinset. Old 409 bottle or something with a squirter works good.
Joe H
Edited 7/30/2005 7:48 pm ET by JoeH
I was thinking what others have said about a coating of dust on the backer board. I was repairing a messed up drywall patch and had trouble with the mud just sort of rolling up and flaking off. Finally sprayed everything with a spray bottle of water and that helped a lot. (mainly got the dry dust of, or at least wetted it, so everything stuck together)