Calibrated tiles

[Time's Ran Out]

I'd only be interested in the quality of the surface.
As I said - due to the nature of this product - I don't believe that the calibration term refers to the thickness of the slate, but it may be calibrated from 5-15mm, and on that note I may well be refusing to fix the 5mm tiles.
There have been occasions when tiles have been thick enough to split and get 2 tiles from 1!

 

[AMtek]

I think the true definition of calibrated slate should mean even thickness and size, but I just Googled it and it seems some just calibrate the base of the tile, leaving a riven finish on the top.

That said I have used this type of tile very often, and if you grade your tiles in order of thickness, you can achieve a good result

as phil said these tiles can still be laid, sort them from thickest to thinnest, lay the thickest tiles first and i normally step up to a 20mm trowel when i cant get 100% coverage with the thinner tiles. its not slate but my pictures of the limestone floor in the "show us your work thread" were calibrated but up to 10mm variance in width, length and thickness and they are all flat with no lippage

 

[The Legend; Phil Hobson RIP]

Another thing to consider is joint width, I would recommend 20mm minimum. Any bad lips can be dressed with a chisel, prior to sealing.

I have some pics somwhere, I will try to dig them out

 

[Daz]

I've done calibrated & uncalibrated slate on floors and walls (now that was a challenge!).
I've found there to be a fair amount of variation where thickness is concerned as everyone has said.
I always use a wider grout joint (as per Phil's post) and I always use a pourable thick bed adhesive for floors.

Daz

 

[Gall.B]

I note Tile Giant are forum sponsors...may be they can answer the case of their so called calibrated tiles...

Think I may have used the 300x300 of these tiles from what I remember they where a cracking price reflected in the quality tho, not very square and a lot of diffrent widths.

Id be taking the 5mm ones back. If you want better they will cost more.

 

[Gazzer]

Another thing to consider is joint width, I would recommend 20mm minimum. Any bad lips can be dressed with a chisel, prior to sealing.

I have some pics somwhere, I will try to dig them out

My client wanted 3mm joints....or less :yikes:

 

[jay]

My client wanted 3mm joints....or less :yikes:

Has he been told today😳

 

[Perry]

In over 30 years of fixing this natural material I've only ever sent back slate once and that was due to the poor quality and uneven layers in the riven surface.
It's a fantastic product with a unique rustic appearance so if you want perfection rather than aesthetics perhaps go for an alternative lookalike.
In my humble opinion the calibration of the tile is the surface area measurements and due to the nature of the riven surface some variation in the thickness is to be expected.

john in thirty years i have never sent any slate back :lol:

 

[One Day]

Calibrated refers to uniform thickness. Rectified refers to machine-cut edges with uniform dimensions to tight tolerances.
Riven means riven. You can't have calibrated riven. That's like having a cold cup of hot tea!

You can normally see the marks on the back of the stone where it has been through the machine to calibrate the thickness.
As it's a riven face you can expect variation but it shouldn't be massive. 1-2mm most.

I recently refused to fix some slate from Topps. The brazilian stuff they used to sell was cheap and OKish but now it's coming from India and it is complete and utter cack.

 

[PHG Dave]

In the case of natural split slate tiles (or sandstone & limestone ) Calibrated is a term used to describe when the tile or paving has had some form of processing carried out to its back face to reduce the variation in thickness caused by it being naturally split, as opposed to sawn/machined.

It cannot give you totally uniform thickness due to the fact that you still have a natural split top surface (otherwise referred to as a riven top surface).

The 'calibration' of the tile could be as little as the use of a sanding disk to take of the worst of the peaks as in typical Indian or Chinese slates (+/-3mm or more!) or a proper machined flat back surface as in a good Brazilian slate (+/- 1mm).

As far as i am aware there is not a controlled standard of what the thickness tolerance should be on these types of material, always check with your supplier before buying and ideally see the variation yourself to avoid nasty suprises.