General finishes water borne stain

[Evan Van Dyke]

Looking for some feedback on my finishing protocol with general finishes water borne products; silly me changed way too many things for me to be able to pinpoint the problem; maybe you can help! The project is a quarter sawn red oak Secretary desk; panel construction with plywood in the fields.

My finishing protocol is:

1. Sand to 180
2. spray with water and dry
3. sand down the nibs with 180
4. spray & wipe with general finishes water borne stain (hickory)
5. spray GF high performance
6. sand down 1st coat with 400 grit
7. spray two more coats of high performance

My problem is when I go to sand down the first coat of HP. I am finding a bunch of scattered fibers that are sanded down to bare wood - not splotches or areas, just short 5-6mm long fibers. I am only noticing this in the real wood- the plywood is fine. I even tried hand sanding with 800 grit and got the same result.

I was able for fix the issue by restaining after the sand down, and the final product looks great, but trying to see how to avoid it in the future. My guess is that the gf stain re-raised the grain more than I was used to with other products. Should I have done a coat of dewaxed shellac under the stain? Or would a dye-based stain work better? I’m definitely going to be trying spraying on diluted dye stain to see if I can get away without needing to wipe off and rub in the stain next time around. Some test boards are in my future.

The other possibility is that the sprayed on hp was just much thinner than I was used to by brush; I could try sanding after the second coat instead of the first. Is that a better option? What else am I missing?

[Jim Becker]

First thing I would change in your schedule is to use much finer abrasive for de-nibbing...I use 320-400 for that or a white pad. And when you sand those first coats, the idea is to only remove additional fibers, not to "sand" the finish. A few swipes to do that is all that is needed. I personally don't do that after the first coat...they are relatively thin when sprayed properly...so don't be in a hurry. If any leveling is required, that shouldn't happen until just before the last coat or two so you have some finish to work with and not break through accidentally to the wood.

[Evan Van Dyke]

You mean a finer grit for denibbing after the water only pass? I had been avoiding sanding with anything higher than 180 prior to the stain to avoid over sanding and closing the pores. I did use 400 after the clear coat, which is where I had issues. I guess I maybe sanded too aggressively, but i was keeping it pretty light and sanding by hand.

i didn’t have to level, as I was able to lay down the finish by spray pretty effectively. I did have a minor drip in one area where I accidentally nudged the fan control when I laid down the gun for a second, but I tipped that off with a brush while wet, and it was perfect when dry.

[Jim Becker]

Consider the purpose of the sanding after you wet things down. You already sanded the piece smooth. You just want to knock off what's sticking up without creating a new surface that would have to have the grain raised...again. (And if the stain is a dye rather than a pigment stain, it matters even less if you use finer abrasives) If you sand it with 180 again after raising the grain, you're exposing new fibers, rather than just getting rid of what's sticking up.