Axminster Granite Surface Plate – Delamination of surface coating

[GreensandsParticipant @greensands]

A couple of years or so ago I bought new a 300x300x50 granite surface plate from Axminster Tools and it has spent most of its time on the bench seeing very little use. Imagine my surprise then after having moving it around the bench to make room for some other activity to notice that at one corner of the plate there was what looked to be delamination of a surface treatment leaving a distinct edge easily detected by a finger nail. My question is therefore this: what is going on here as I had assumed that the working surface and sides was natural granite and not as it now appears, some sort of surface coating which has been inadvertently chipped off. The photos hopefully illustrate the issue.

[bernard towersParticipant @bernardtowers37738]

looks like its had a bit of a clout

[Charles LamontParticipant @charleslamont71117]

DON’T PANIC – it looks like a left-over bit of magic tape. I think I can even see the serrated edge left by the tape dispenser.

[Charles Lamont]

On Charles Lamont Said:

DON’T PANIC – it looks like a left-over bit of magic tape. I think I can even see the serrated edge left by the tape dispenser.

Well-spotted, Charles !

MichaelG.

[Nigel Graham 2Participant @nigelgraham2]

A remnant of a protective film, part of the original packaging for transport.

They aren’t actually “granite”, these dark-grey, finely crystalline plates! The masonry trade tends to call any hard, crystalline stone, “granite”. It’s still an igneous rock, I think a type of basalt. Worktops, gravestones and surface-plates are machined from quarried slabs but basalt is used in some engineering applications by melting and casting.

[Mark RandParticipant @markrand96270]

3M sticky tape!

 

It’s probably gabbro. Nothing wrong with it. Slightly softer than granite due to the lack of quartz, but stiffer. If it is, a strong magnet will ‘just’ stick to it.

[Colin HeseltineParticipant @colinheseltine48622]

My first thought was bit of magic tape

[Mark Rand]

On Mark Rand Said:

3M sticky tape!

 

It’s probably gabbro. Nothing wrong with it. Slightly softer than granite due to the lack of quartz, but stiffer. If it is, a strong magnet will ‘just’ stick to it.

That’s interesting – I’ve just tried a neodymium magnet on my ‘granite’ surface plate (which seems similar to the OP’s), and it does indeed stick weakly.

[Author]

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