I love old chalkboards for tile work . I had put cut chalkboard in my entryway and you could not ware it out . When I did take it out I reused the bits I could save on my new floor . The slate is dence and suited to use in a shower . Think of a old slate roof .
There or some things that you may want to think about before you do a large amount in a shower . It is dark and will show dirt and water spots . 4'/4' are large sheets and I would use a larger notch trowel 1/4 3/8 or even 1/2 1/2 if your walls are not dead on. Cutting is not hard but you will want to use a hand held wet saw http://www.contractorsdirect.com/Til...d-Held-Saws.It
will give you nice cuts .
All the slate may look the same but the different thickness will show up and will be hard to deal with if you don't cut the slabs down in to smaller tiles.
lay it out on the floor and check to find ones that will match up with each other.
You could use your slate mixed with another stone or tile and come up with something that looks great and use the left overs for other projects .I cut a scrap and mounted it on my sons door so I could send him nice little notes .
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