So on a job the other day..I left one of my guys to finish sanding and decided to apply Universal sealer as first coat.

assuming no issues I leave.

Come back next morning and what do I see?

Black stop marks at butt joints, various shades of black/grey..anywhere an applicator stopped left a mark and some bigger areas.

I was freaking out..I first think humidity but that would turn white spots.

I think he screwed up and went to heavy..but closer examination reveals there is no over build/puddles, heavy lap marks.

WTF?

I call Zinnser and speak to technical.

Turns out the alcohol in the product reacted with Iron in the wood.

The Tech tells me its a rare occurrence and sometimes in farming, some trees are absorbing more iron in certain area for one reason or another.

I am like "What?"

sounds like a bunch of crap. I tell him, look, I don't want to have to sand this job again.

He tells me it wont be necessary.Previously I was trying hand sanding and even buffing..went through 5 screens.
It was helping but correcting it.

So anyway here's the fix..he tells me now worries you don't need to sand.
Get some Oxalic Acid and mix 4ozs into one gallon of sealer and simply touch up the effected areas.
The acid will neutralize the effect. He said no need to sand/screen etc but if wanted to go ahead.

i really didn't believe him and was reluctant.I buffed the hell out of it.. got the acid ,mixed it and did a test spot.. Sure as Sh** it worked after 5-10 minutes.

I coated the whole floor again to be sure and literally watched the black disappear.

Was amazing..I learned something new after 24 years in the biz..and was humbled to say..

damn there are people in this world a helluva lot smarter than me.

I mean who figured this out?

I guess there are really tried and true tech people out there. Musta been one of there lab people figured it out. I've never heard about that but then I'm not a finish guy.

Cool. What kind of wood did this happen to ?

Paul


it was typical red oak

That's the fun of the business, there's always something out there to give you a challenge. I had 2 distinct problems with alligatoring on two different jobs. One was a typical oak floor, but in a depression ( ferns growing everywhere ) and the moisture was just killing specific boards in the floor. We let it dry for 2 weeks, came back and scraped and sealed the individual boards one day, came back the next to recoat the whole floor. It down poured the whole time. Most of it wasn't an issue, but the steps going to the walk out basement/garage...the last three you would coat one, start the next and watch the previous one alligator up...it printed up through the wet poly...never seen such a thing in 15 years of recoating. Then I had it happen on a permagrain floor in an area that moisture shouldn't have been an issue.

This year, I got to discover the dangers of using water based finish on a water reduced dye stain. Did you know that dye stain really, really likes water? I didn't. My waterbase started to turn to jelly as the dye reacted with it and started to coagulate it within the line of finish I had laid. What a nightmare.