Sprayed & brushed Shellac on Red Oak issues....HELP!!!

[Dave Gaul]

Using Zinser's Seal Coat (de-waxed clear shellac) on Red Oak that was coated with BLO first. No grain filler or anything else. Sanded to 220, BLO, then Shellac.

Just got the new Milwaukee HVLP/Airless sprayer. Sprayed shellac in HVLP mode, 2 coats. Was not happy with a certain area of the piece, sanded back, then sprayed again. Still not happy. Sanded, sprayed again. No luck in same area. Then, I turned to brushing, so saned again, brushed on a coat. While this coat was drying, I took a peak, and then I saw what was causing the poor results...

The shellac was sticking to the darker grain parts of the wood, but not the lighter grain parts! It seemed like the shellac was "building" on the darker grain portion of the wood, and totally rejecting the lighter grain portions, but only in this one area?

My fix right now is to sand back the piece, and apply a different finish, maybe polycrylic (because I have some on hand) or something else, a varnish maybe?

Can someone explain why this is happening?
Anyone have a suggestion to fix?

[Joe Chritz]

I am not sure what darker grain parts is indicating. It could be bridging, which strangely enough normally is a problem with waterbourne finishes and the sealcoat is supposed to solve it.

Shellac isn't a one coat wonder, I wonder if a couple more coats would solve the issue. The open grain pores in red oak cause lots of issues.

The other possible problem is bleeding of the BLO. It has a tendency to migrate out for a while on some pieces.

Any chance for a picture?

If shellac has a problem no finish is likely to do better. Shellac's claim to fame is being able to be used just about anywhere.

Joe

[Dave Gaul]

It is very strange, it seems like the shellac is "jumping" from the light wood to the dark wood of the red oak!

I tried just ignoring the problem, lightly sand with 320, then re-apply, this seems to compound the problem, building up more on the dark wood and still nothing on the light wood!

[Dave Gaul]

Oh, and I do not believe it is BLO bleed out, only applied one coat, and wiped up any bleeding, checking every 30 minutes for a couple hours. Piece sat for a few days before I got around to shellacing...

I can post a pic later if I don't solve the problem tonight!

This is my first build for $$ and it's for a coworker, hoping to get it done right and soon!

[Howard Acheson]

Is this solid wood or plywood?

[Dave Gaul]

Solid Red-Oak... ~ 5/8" thick...

[Phil Phelps]

Are you experiencing the open pores of the oak that are not filled with the clear coat?

[Tony Bilello]

The only other thing that I could think that would do this is some kind of contamination, usually caused by some oil or grease. I am probably all wet on this one because I am not familiar with BLO or Shellac, but just a thought.

[Scott Holmes]

Sounds as if the shellac is soaking into the large pores of red oak...

Not sure what you mean by dark wood and light wood. Latewood and earlywood possibly?

[Dave Gaul]

Scott,

Yes that is what I mean, latewood & earlywood...

Scott & Phil... yes I believe you are correct.. took another look last night and with the help of a friend who did lots of ww'ing in his younger years, it appears that I sanded through the first layers of shellac and the open pores are soaking up the shellac like a sponge!!! I must have sanded WAY TOO MUCH and even sanded away some of the BLO layer?

Tony, I wondered the same thing, but the area in question appears to be completely bare, thus acting like a sponge!!

Thanks to all for your help! I now know what to do, and what NOT to do next time!!!