Dull Polish vs. a 240 Silicon Finish.
We have always advocated a 240 silicon finish for certain applications rather than a standard ’Dull Polish’ and a short but interesting conversation with a colleague in our Industry raised the question ’why is a Dull Polish still requested / available? Why isn’t all material produced to a 240 silicon (2K) finish?’ The question was raised because one specific stockholder ensures all their polished sheet in stock is produced to a 240 silicon with a surface roughness of less than 0.5µm. This is in contrast to other stockholders who may just keep a Dull Polish, or even a variety of different grained finishes. Whilst we certainly don’t pass comment on our customer’s ordering habits (except to say ’thank you’) I do understand why the question was raised. There is still a huge market for a standard Dull Polish on sheet—produced with a grit of 180-240 grit aluminium oxide—and this is often used on internal architectural projects as well as many other applications. The mean roughness average on a Dull Polish with a 240 grit aluminium oxide abrasives on sheet is 0.6µm—not a lot different to the 0.5µm on a 2K finish. Yet it’s not just about the smoothness of the surface, but also about the ’clean cut’ grain pattern a silicon finish achieves. There are both positive and negative connotations to this—a 2K finish is less forgiving than a Dull Polish as the very smoothness will highlight any visible ripple in the substrate, and often defects that are disguised by a Dull Polish are not removed or camouflaged by a silicon carbide finish. Both finishes have their place in the UK market although it is always of course wise to check what application the customer is using the polished sheet for in case a 2K finish is the best suited. The second part to the question was if there is a cost difference between these finishes and the answer is that on standard sheet, no there’s not. Twenty years ago there was a difference but due to advances made by the abrasive companies this is now negligible meaning the same price can now be charged. And the final part to the question was which finish do we like best! If the correct finish has been applied for the required application then either a 2K 240 silicon finish or a Dull Polish can look stunning and really enhance the end result and so we are happy to sit on the fence on that one (providing it is 316 stainless steel polished to a 1K/2K for external architectural use!)
240 Grit Dull Polished Finish (2J)
240 Grit Silicon Finish (2K)