Polyurethane products especially water based ones tend to foam when you agitate them.
Polyurethane on marble table.
When a drop of water soaks into the marble and doesn t bead up it s time to seal.
Your question was can i put polyurethane on marble i answered this question.
It will penetrate the surface and protect it.
The marble is less likely to scratch as is why it is used as a cutting board surface.
A sealer would be good to stop staining however bleach or a marble cleaner can be used to remove stains.
On shaped edges use synthetic steel wool such as scotch brite pads labeled very fine tabletop finishing.
Turn an old table into a marble master piece with just some simple steps some paint and sticky back vinyl.
Poly will scratch and flake off looking worse than a few scratches in the stone.
Watch as rachelle from originally worn attempts and slightly fails to finish a table top with annie sloan graphite unicorn spit polyurethane.
I would use a product called soy gel.
Use a sealer made to seal marble.
I purchase a marble topped coffee table for 5 because someone put polyurethane over the marble so it wouldn t chip.
Polyurethane tends to gum up sandpaper so use paper or pads that resists clogging 320 grit.
You can get from here.
Dip a paintbrush into the gloss polyurethane varnish and apply an even coat from one end to the other using long straight strokes.
So in my opinion i would not use polyurethane on your marble top.
I also told you the only viable fix for your problem.
Best to stay away from poly for this purpose.
Clean off the white stuff.
The foam forms bubbles on the surface and if they harden they can be difficult to camouflage.
I want to remove it but not sure how.
I m sorry there isn t a cheap easy fix for your problem but i not only answered your.
Although it is possible that your table has a polyurethane or varnish finish it s much more likely that the marble was polished to a high gloss that has become scratched and dull.
Let the polyurethane sit for about 10 minutes after stirring to allow the foam to settle.
Apply a second coat if you desire.
A quick hand sanding between coats flattens our flaws before the next coat.
The table is going to be my new desk but at the m.