grain filling, vinyl sealer (Mohawk) and pre-cat lacquer

[stepace]

Hi. First time poster here...
I am trying unsuccessfully to start finishing some cabinet doors for a bathroom vanity that I am building. This project has many firsts to it for me and I haven't done anything more than a simple coat of poly on previous projects.
I am using Mohawk vinyl sealer and Mohawk solvent based pre-cat gloss lacquer. I want it to be glass smooth when I am complete with it. I tried using BLO and pumice to fill the grain on a scrap piece of wood. Once the BLO dried over night, the pores in the bubinga were left with the white powder residue from the pumice. Putting a coat of sealer on the wood left me with a bunch of tiny white streaks in the grain streaks. So, I determined that won't work for me and I would just apply sealer, sand it down and repeat until the grain was filled with the sealer. I tried that today on the panels for the doors- applied a coat of sealer, waited fifteen to twenty minutes, hand sanded with 220 grit paper, wiped with a paper towel and mineral spirits and then applied another coat of sealer. It dried with streaks of powder residue from sanding underneath the second coat of sealer. I'm assuming I did a far less than thorough job of wiping the powder left from sanding??? I have since sanded with 120 grit using a ROS to get back to raw wood. There is still white powder in the grain. I do not want to sand any further because I do not want to mess up the fit of the door panels. What's my best bet for correcting the issue that I created for myself? I am now thinking I should try Behlen's water based grain filler in hopes that it would pack down on top of the remaining white powder left in the grain. Do you think this would work? How do I prevent this problem in the future? Thanks in advance for your help!

 

[Robb Parker]

Pre cat and post cat or vinyl are not grain fillers. They have a definitive amount of mil thickness that can be applied and they cannot be over applied or they will fail. Normally this is 5 mils wet, but may differ per mfg. Also if you sand through one layer to the other you will have witness lines that will show. Your best bet is to use a grain filler, preferable solvent base if your using lacquer. Don't, I repeat don't wipe panel with mineral spirits to clean. Blow off with compressed air and tack cloth dust off. If you want to use sanding sealer as a grain filler, use nitrocellouse lacquer for sealer and top coat. It's not to be confused with pre or post cats. It can be used to build with multiple coats and behaves differently as each coat burns in chemically to the other for one coat. No witness lines. Nitro is softer, less water resistant and not as chemical resistant as pre or post cats. Mohawk is a good product mfg and will perform well for you if properly applied. Get the mds sheets and read as they will tell you all specs related to that product.
Robb
Heritage Woodwright llc

 

[Robb Parker]

Sorry, probably didn't exactly answer question after i reread you post. I haven't finished bubinga but alot of mahogany, would think about the same. Do step boards!
My steps for most open grained woods.
Sand to 180g
Grain fill w/ solvent based grain filler.
Sand with 150g (obviously tack off dust after each sanding step)
If need repeat grain fill step
Sand with 150g (don't start with less than 150g or you'll pull filler from grain on either sanding step)
Dye or stain
Spray vinyl sealer
glaze
Spray vinyl sealer
Maroon scotch brite
Spray sanding sealer pre cat or post cat 5 mils wet
Mis nomer don't sand, scotch brite with maroon scotch brite (if you have nibs that scotch bright won't take off, lightly! hand sand with 320g
Spray top coat 5 mils wet
scotch brite
Spray top coat 5 mils wet
If your going to rub out, I use wax and 0000 steel wool, will give a nice satin finish, if your going for gloss finish, you'll have to polish unless off gun is ok for you. But that's a whole nother discussion. I personally don't do any other that satin finish. Don't like gloss and scratch too easily under daily use.
Robb

 

[stepace]

Robb-
Thanks so much for the great information. It sounds like completely sanding down and starting over is the way to go along with starting out with using Behlen Pore-o-pac grain filler- I think this is considered a solvent based filler. I'll make sure to follow all of your steps. I guess I got confused when reading some other information ahead of time not realizing how different NC and pre-cat lacquers are.
Thanks again.

 

[Robb Parker]

Stephan- You'll do ok with that Behlen. Nitro and pre cat are two different animals.
Robb