Mini jack / prop / wedge

[chuckey]

Most el-cheapo shower trays having a taper on their outside. One way of making a good seal is to totaly fill this tapered recess with some waterproof goo*, then you have a flat area to lay tile slips on before tiling the walls.
* the front end of the side tapers may be visible when the job is completed so they could be finished with with silcone goo.
Frank

 

[Penners]

waterproof goo

Don't you try blinding us with science.

 

[Moo]

...el cheapo shower trays having a taper on their outside.

How are shower trays made without a slight taper? I've always understood that they have to taper slightly to allow them to be removed from the mould, rather alike a geometric jelly.