Cementing Hardibacker to plywood floor: which trowel to use?

I have a square notched trowel, and an angled (triangle) notched trowel. What is the appropriate trowel for this job? When would I want to use each? In this case, I am using thinset to adhere the Hardibacker. I will later be doing 1-inch hex tiles to the Hardibacker with the same thinset and am wondering which trowel to use for that also. Thanks! Adam
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Adam wrote:

The purpose of the cement board is to get a level surface. The purpose of the thinset is to fill voids between the flat cement board and the less flat floor. Your fastening needs to be done with screws/nails, mortar doesn't stick well to wood. _____________________

The shape of the notches is less important than the area. Could be wrong (long time since I used mastic) but IIRC a "V" notch is for it., square notch for mortar.
The idea is to use a notch size so that the residual mortar will adequately support the tile and that notch size varies with the tile size. Ideally, it would spread out under the tile when it is set and/or beaten so that there is a thin but adequate layer under the entire bottom surface. In the case of your 1" tiles you need a thin notch...1/8" I would think. For your cement board, you need a larger notch. 1/4" I would guess if the ply is reasonably smooth. Maybe 3/8".
-- dadiOH ____________________________
dadiOH's dandies v3.06... ...a help file of info about MP3s, recording from LP/cassette and tips & tricks on this and that. Get it at http://mysite.verizon.net/xico
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Try SCREWS
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I used screws to attach the hardiboard to the plywood. The thinset is for the tiles.
er
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Hm, I was told that I should use thinset AND screws. So I guess the point of the thinset unser the backer is not adhesion, but support and filling cracks.
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My limited understanding is that the thinset under the backerboard bonds to the subfloor and the backerboard, levels minor imperfections and creates a very solid substrate for the application of the tile. The subfloor and backer board become one.
Colbyt
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