Dull spots

[leftypete]

Using minwax wipe on poly.  Started with water based, put 3 coats on.  Wasn't glossy enough and seemed to be dull spots, switched to oil based...( Not sure if this was a good idea...anyways, little glossing, but still some dull spots...

Sand down???

[Bizman62]

Hi and welcome!

Some finishes don't mix, some do. I suppose that if you've let the water based dry properly the oil based may work, after all they're both some sort of liquid plastic. If you're not in a hurry - and you shouldn't, this isn't a hobby for hasters - let it sit for quite some time to see if the finish crackles or wrinkles. In that case sanding down is the only true option.

Regarding the dull spots, could they be described as the wood sucking more poly at certain spots? Like looking dry while other parts are still dripping wet? I've never used wipe on poly but with oil finishes (Tru/Danish etc.) that is a common thing and requires just more finish on those spots until the pores are full. Sometimes it's because of improper sanding, sometimes it's jus the wood. A pore filler might have helped but for what I've heard finding one that really works with a clear finish can be challenging. Some builders just apply dozens of thin layers, sanding in between, to get a mirror finish.

Sanding between layers is also important as especially the first layers of finish usually raise the grain. Fine papers, from about 320 up the grits to get a satin matte finish is the goal there. It may sound weird but for a perfect mirror finish you'll have to sand even the last layer. Very lightly using fine wet'n'dry papers but still. I've hand sanded a clearcoat up to 6000 grit wet before moving to fine abrasive polishing paste The result is pleasing... But I used sprayed 2k poly instead of wipe-on.

[leftypete]

Thank you.  I appreciate your advice. I did end up sanding down.  Still wrestling...

 Just surprised me since I did the exact same wipe on poly on an ash strat and it was glossy and almost perfect before polishing.

 

[Bizman62]

25 minutes ago, leftypete said:

Just surprised me since I did the exact same wipe on poly on an ash strat and it was glossy and almost perfect before polishing.

Sometimes you get lucky, sometimes not.

There's so many things involved, starting from how you've slept the previous night. Is your hand light as a feather or do you push all the week's frustration into your work, do you feel like having to go back to some spots...  The temperature and humidity affect the open time of the finish, the barometric pressure also has its say in how the finish levels.

Further, as wood is a living creature of Mother Nature, the grain direction matters. A curl in the grain is pretty but when studied closer the grain is going into all directions in such spots, even partial end grain. Such spots are the most difficult to sand, no matter how many times you moisten to raise the grain before sanding again and again, the finish will raise the faintest fuzz to mimic a frightened hedgehog.

What I'm trying to say is that a smooth and solid surface is the key. I suppose wipe on poly is applied very thinly and if the grain tends to raise at certain spots it ends up as a dull spot. Sanding very lightly between the first layers might help as the finish will glue the fuzz in place but even that doesn't change the directionality - some spots will shift light in a different way no matter what. Anyhow, using the first coats as a sanding primer might help.