Thread: bubbling or pitting in floor coating

Originally Posted by mol

I have had a professional put a water based poly coating on a T&G 120x22 mm hardwood floor. My problem is that I've had him back as the coating bubbled. He stripped back recoated the floor, and now 8 hrs later the floor is bubbling again It has a great deep shine but this Bubbling or piting is again showing. Am i being too picky? or is it a shoddy job I dont know! Do any of you out there have an opinion? If so I would love to hear it.

is it bubbling(raised lumps) or pitting(hollows)
if it bubbles it could be;
the type of timber reacting with the finish(maybe)
dust falling onto the drying finish after application(vac the walls)
or wrong mixing if its a 2 pac finish(unlikely)
if it pits;
the finish falling into the open grain of the timber(more coats needed to fill in)all cut back between coats.
hope this helps

hi,this happens when the top coating is put on too thick for the air that is trapped in the pores of the timber to escape ,thus sealing air under the coating this air expands and voile bubbles ,three thin coats always never one thick coat is the old saying (not that im old its just that the saying is !)

Thanks for the info makes a lot of sense to me. The contractors boss came out today and was very pi###d off with his worker he also missed two doorways he's going to fix it soon.

Mol, is it cold where you are. And is the floor cold to touch ? The pitting you are getting is called a solvent boil. I would say you are using a polyurathane on your floor. It is caused by a speedingup of the drying process caused by cold weather. What happens is that the polimors react rappidly under cold conditions and a very thin layer on top of the coat dries quicker than deeper in the coat. The solvents try to release and pushes its way through this thin layer . It causes a pin hole and under normal conditions it would settle and flatten out, but because the thin layer is harder and dry, it stays perferated. I would say that you are using a semigloss. But it still happens with a gloss. This is repeairable. The contractor needs to use a 120 grit screen grit and hard cut back the floor untill there is no sign of the pitting. IT is easy to do. Follow up the cut with a 180 grit to take out any swirl marks left by the 120 grit. This 120 and 180 cut is done on his polyvac buffing machine. he wont go down to timber because the other coats of poly will protect the timber , all he is doing is chopping out the boils. He then MUST MUST MUST MUST use a wet edge extender in the coat . This will cause the poly to dry eaven and it wont boil up. Make sure the contractor understands this procedure or it will happen again. Tell the guy for him to take his time and not hurry. 20mls per litre is the ratio of flow aid required. He can purchase it from his poly supplier. He also needs to run around the edges with a 100 grit on a orbital sander to cut them back as well. you will have succes if this is done.

Thanks larry,
Thats the first Ive heard of a wet edge extender but i will mention it when they come back. You are 100% right that it was cold about 10 degrees (cold for brisbane) and raining maybe this also added to the problem. He is pretty enthusiastic to get the job done properly as I still have 80 sq mtrs of kwila to lay and polish. Maybe, I might ask if there is a polisher out there that will do the job properly in the first place via here