Slate is a natural product – not a man made one.
When you choose to work with or buy a natural product, you are getting something made by nature, chemistry or geology. It is one of the reasons we choose to work with Cornish slate. No two pieces will ever be the same.
If you have a piece 300×300 mm and cut it into 4 individual pieces, they will all likely turn out differently when they are cleaned and polished.
Whilst the slate is predominantly grey, you get various shades when the slate is polished up. Polishing the slate means ‘smoothing the surface’ with coarse to fine diamond polishing pads. The finer the pad, the nicer the finish and with slate, the finer you go, the ‘shinier’ it gets. Quartz and other minerals tend to be a bit ‘shinier’ than the surrounding slate too.
As part of the geological process when the slate is formed, the compressed mud’ (which becomes slate), has materials of different hardness that form within it. Quartz is much harder than the surrounding slate and when the lettering is sand blasted, the quartz wears at a much slower rate. This will leave lines or maybe bumps in the lettering.
There is nothing to worry about.
These lines or pieces of quartz are not faults or cracks and will not affect the sign in any adverse way. In fact, what it does show, is that you have a product created by nature – not man. Slate is a layered product so splits occur along the ‘grain’, rather like wood. If a piece cracks or splits during the sign making process, then it is discarded. It goes with the job. Should a sign ever split along a line of quartz, we will replace it free of charge.
Sandblasting our lettering.
Sandblasting is a form of erosion. You will see the effects of erosion wherever you look along any coastline – or valley. Rock wears at different rates and a jagged rock face is the result of softer rock eroding faster than harder rock around it. Sandblasting is a super fast form of erosion so the same results apply. The soft slate erodes faster than any hard material. This can leave lines or small bumps. This is perfectly normal.
Why do we sand blast our lettering?
Sandblasting allows us to be very flexible creative and also very precise when it comes to designing. We can use many hundreds of fonts, mix up fonts and do them at very precise sizes. If you want lettering a set size, then we can do it. This is not achievable with routing! This is why many online sign ordering sites are so restrictive with their offering.
I am not a geologist, so if anyone reading this is and can help with some explanations, the drop me a line and I will include it in this post.