Is all fine grit count sandpaper called wet/dry?

Question

I need to start getting into sharpening and honing so naturally one of the ways I could go would be to get some sandpaper in the 500 + grit count range. (That decision is based off a great video I saw from Paul Sellers that suggest this being a more economical method when starting out. )

At most home improvement stores, in the sections where I normally find sandpaper, the highest grit count I will come across is around 320. However, in automotive sections I find the higher grit counts I am looking for which is usually up to 2000! They are advertised as wet/dry paper.

So is all the very fine/high grit count paper actually wet/dry sandpaper? Is wet/dry just a gimmick of terms? If I find anything with the right grit count does it matter what kind of paper it is (assuming there are multiple kinds)?

Answer 1

So is all the very fine grit count paper actually wet/dry sandpaper?

No. You can get regular papers that go to 400, 600 and even 800 grit (or equivalents). But as a broad generalisation if you see paper that's dark grey, with dark backing paper, it'll be the wet-and-dry type even if it doesn't specifically call itself that.

Is wet/dry just a gimmick of terms?

No, absolutely not. They use a waterproof adhesive, and the paper itself is resin impregnated to make it water-resistant (you notice it when you try to saturate it and the water initially beads up on the back).

With regular sandpaper the adhesive can be very water-soluble and the paper itself will just fall apart if dampened (note: with water).

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Now you didn't ask about this but I would recommend you not go with sharpening on abrasive paper. Inexpensive diamond plates and oilstones are available and one or both are a much better intro to sharpening and far far better value, not just in the long term but even initially since high-grit paper can be fairly pricey.

And as the final step I always recommend stropping and always with a homemade strop... woodworkers who buy strops should hand in their woodworking cards :-) As Paul Sellers explains and demonstrates stropping gives that final refinement to your edges in a fast, economical and user-friendly manner. It makes the difference between a sharp edge and a really keen edge in older parlance.

Answer 2

When polishing metals, it is quite common to use very fine grit (high grit count) sandpaper. I use it frequently. It's also recommended to use up to 1500 grit sandpaper when preparing certain wood surfaces prior to oiling with certain products – I did it recently with some Oregon when using a citrus oil and it was smooth as a baby's bottom afterwards (and it smelled amazing too)!

With 2000 grit wet/dry plus metal polisher I have managed to get mild steel to basically look like a mirror. Doing that will give you a workout, I can tell you that. It makes polishing aluminium a breeze.

Wet/Dry sandpaper is not an oxymoron, it literally means one can use the paper as-is (i.e. 'dry') or with some abrasive/'polishing' liquid such as Brasso (i.e. 'wet'). Think of the way you use a cleaning or polishing product with a cloth, this is literally how it works. Wet/Dry sandpaper often is a bit more expensive as the paper ground is tolerant (i.e. it has something of a resist) to the wetness.

Technically the misnomer is the word 'sandpaper': Wet/Dry is not traditional glass/sand beaded paper normally used on wood but a very fine carborundum grit paper.

Because the majority market for these fine grit papers is for (metal) polishing where an abrasive compound can make a huge difference, this is why pretty much all very fine sandpaper is Wet/Dry. But you can easily get 500 grit paper in the other standard paper substrates at most home improvement/building stores.

Check this quick video out which as an example:

How to polish a dirt bike frame

But the video by Paul Sellers is much more instructive, he just takes it as a given that you know what wet/dry 'sandpaper' is.

Answer 3

Wet /dry is really a specification of how the paper has been fabricated and in particular what kind of adhesive. Wet paper uses a waterproof adhesive, and a waterproof backing which allows for continuous usage with water. The advantage of wet sanding is to clean the area up so the surface is not scratched by the debris build up, as well as keeping the paper clean ... other wise it would clog. Wet paper can also be used with solvents, for some time at least, until the adhesive is dissolved.

Dry paper is just that, paper and it takes about 5 seconds to turn it into gritty sticky mush, when wet with water or solvents..

the higher grit ratings are for finer and finer surface sanding with water.

I have 24 grit Wet paper and trimkuts for the 4 1/2 inch angle grinder. the grit does not matter with the Wet Dry or Dry types.