Re: ATM broken cementtool

[Malcolm Macdonald <toliman@wave.co.nz>]

At 03:28 PM 11/06/01 +0200, Klaas Honders wrote:
>
>Hi all,
>
>         A few weeks ago I made a cementtool for a 13" project.
>This was the first time I made one and it looked excellent till today.
>When inspecting this disk I noticed a very small crack running from the edge
>to the center over about 3".
>Light knocking caused an increase it went on to about 4".
>So useless.
>What did I do wrong? Missed some kind of secret ingredient?
>Dried to quickly?
>I used pure cement(portland)
>
>Klaas Honders
>
>k.honders@worldonline.nl



I don't know why your tool should crack unless it was moved before it was
fully set. Mine are usually set overnight, and once I remember grinding
(very carefully) the next day.

I began making cement tools when I first heard of dental plaster being
used. Didn't know what it was , and couldn't get it so I used portland
cement instead, and I've never had a frailer yet. Perhaps I have just been
lucky.
I don't go to any trouble: no glue no sealant or paint, (ever heard of
concrete softening or dissolving in water?) and I've had no trouble with
scratches.

Secret ingredient?  Well Maybe.  I usually mix the cement with fine sand,
about 50/50 mix. I do this because the sand is free. but perhaps it gives
it more strength also.

Just a tip. If you are using stones instead of tiles, wash them to remove
small stones and fragments. Small pieces will wear away and the last
fragment may come loose.

I recommend cement tools. but not cement laps. its too hard to get the
pitch off again. Mels plywood laps work well.   

Good luck    Malcolm.
Malcolm Macdonald.
Rotorua, New Zealand.

Experience is something you get after you need it.