Hello All. I am working on an engineered hardwood floor application (BR111 Brazilian Cherry) in Texas. I decided that for the best protection of my investment, I would install Bostik MVP4 prior to gluing down my floors. After cleaning the concrete subfloor and ensuring that it was level, I opened my 5 gallon pail of Bostik MVP4. I noticed that the product had separated, an oily amber colored liquid was on top. I did my best to mix the solution into the product. Is this separation expected and was mixing it the right thing to do? Anyway, so I applied the MVP4 to the subfloor as directed on the pail using a v notch trowel. Approximately 1 to 2 hours after the application small bubbles began forming in the vapor barrier. 16 hours later the bubbles are gone, but there are craters (approximately 50 in a 100 sq ft room) ranging from a penny to quarter size. Is this normal? What could cause this? How will this affect the integrity of the vapor barrier? Should I go back and fill these craters? I have searched on the internet and cannot find anything related to these questions. I have also sent Bostik the same questions. Any help is very much appreciated!

Whenever I open a can of MVP4 I always have a stir stick ready,( I use a scrap piece of t-moulding). The shelf life of MVP4 is 1 year, but as it goes through the year the seperating is common.

I always warn customers,( so they don't freak out) that they will notice bubbles and craters as the barrier flashes off, sets, and cures, this is common. No, those little craters don't need to be filled prior to spreading adhesive.

Good questions, I haven't seen where Bostik spells these out for people.

I use a paddle on a drill. Same one I mix patch and SLC with. Love the craters, looks kinda looks the moons surfice.

"Love the craters" . Yea, probably better to use a paddle. I may just switch over. I'll bet there's more bubbles and craters using a paddle ( injecting air) . But...it's mixed better, and little bubbles no troubles.

Any craters are filler with adhesive and basically patch the crater when you spread adhesive.

The adhesive has the same moisture barrier properties as the MVP4. It is the thickness that makes the moisture barrier.

What I don't like about MVP4 is the little red chunks(Looks like neoprene) of rubber, that once dry are little mountains in what is suppose to be a smooth surface.

Some pails have it and some don't.


WFM Planiseal from Mapei is much better and less costly.

Not once have I ever run accross "little red chunks" in MVP4

Seen some chunky mvp4 but not red chunky. Probably just old stuff.



Agreed obviously the thicker the better but I still feel having one layer totally cured, skinned over and set, then glue is going to be better than one whole app of adhesive. Just the way my brain works I guess.

Besides getting paid for the mvp4 app is better than giving the money to the adheive manufacturer. If it were my floor I would not trust the one app systems yet.

I'm not a big fan of the system myself, for the same reasons. I have a feeling it's definetely up and coming and going to be hard to avoid. More cost effective and less disruptive for customers, and I'm sure manufacturers have their motives. Once installers start using it...if your not, it will put you at a competitive disadvantage.

Probably right Howard. But I wonder what their warranty says. Will they pay for the wood and labor as well should the adhesive not perform up to par? I don't like getting stuck holding the poo bag.