Water popping is raising the grain during the sanding process by spritzing water onto the surface in-between sand paper grits, to get a very flat & smooth finish on a piece. Let me explain…
There are many different grits of sandpaper ranging from an ultra abrasive wood chomping 40-grit to a grain-closing 2000 grit….and well beyond for other applications. Which is best for the type of finish you’re after? Is there a general range to stick within for woodworking? Why not always build up to the higher and higher grits for an ultra smooth & glossy finish? It’s not quite that simple.
Within the realm of woodworking the general grit range you’ll stick with is 60-600. 60 grit is for the rough n’ tough boards that really need to be stripped. 400-600 grits are rarely used unless it’s a specific type of project or finish requirement. That leaves the 80-320 or so range…which is most common.
When sanding, the proceeding grit is generally meant to level (or sometimes called remove) the previous grit sanding patterns. A 300+ grit can leave a really smooth surface that’s smooth to the touch, looks nice but has one flaw — it can struggle to be a good surface for the finish to adhere to.
As you sand higher and higher in the grit range, the grain of your wood gets tighter and tighter. This ends up being a restriction point for many oil finishes to soak in and adhere properly which runs the risk of your project being unprotected.
Enter water popping. In-between each grit of sanding a light spritz of water is sprayed onto the wood surface and then air dried. This inherently causes the grain to “pop” up allowing the next grit sandpaper to grab those grains and smooth them out to match the remaining grains that did get sanded on the prior grit. The process is simple and goes something like this…
80 grit > water pop > 100 grit > water pop > 120 grit > water pop > 150 grit > water pop > de-dust > finish seal
Now this can be modified per the finish you’re using, the specific needs of the piece and your desired end result – but it’s a good general range to reference. Using the method above you get a surface finish that feels super smooth (as if it was sanded all the way up to a 400+ grit) but a wood grain structure that’s still open enough to allow the final finish to penetrate and soak in for years of protection.
A simple technique that yields great finished piece results is a win in my book. What are your thoughts on ‘water popping’ a project?