Expert: Labman - 8/2/2005

Question
Thank you very much. I will try to find a place that sells the product you mentioned. What I don't understand is

one company calls there product non-toxic (JW Etc) certified by Duke university, but when you ask it has 390g of VOC per one liter

another company says their product is solvent free but has VOC

Free of what? Do you know when they mean they are solvent free when they still have VOC. This is water based product from Basic Coatings called Street Shoe.

Thanks again.

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Followup To
Question -
Thank you very much. I am sure the product you recommend is good. Is it water based? We wanted water based because were told other products are darker in color and will eventually turn yellow.

Could you please clarify if solvents and VOCs are the same things. Can polyurethane contain no solvents but still contain VOC. Can there be additional solvents besides VOCs?

I have a list of some chemicals in the product I can easily get and was told is very good.

N-Methyl-2-Pyrrolidone  5%-10%
Ethylbenzene
Oxirane
Hydrazine
Benzene
Diethylene Glycol Ethyl Ether 1% - 5%

Will all of those evaporate completely and make the wood finish fairly safe if piece is ingested?

Thank you very much again.

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Followup To
Question -
Hello:

I wanted to use as safe of a product for my new unfinished hard wood as possible. I was told I need to use sealer and then polyurethane.

Do all solvents, especially harmful, and VOCs evaporate with time or do some stay when the floor is dry? Can those then be damaging if a child scratches and puts it in the mouth?

Thank you.
Answer -
It is good to put your child's safety first.  You don't want the child exposed to the fumes from any coating.  The water based coatings contain much less of the VOC's but ones even more dangerous because of their affinity for water.  You want the child out of the house.  Let it visit its grandparents, friends, anybody you know and trust.  

The good news is that once the finish is dry, virtually all the VOC is gone, and what little remains will near zero in a few days.  As long as the child is out of the house during application, the exposure will be nil.  Carefully follow all the directions using the ventilation as advised.  

There is a much tougher, almost child proof type of urethane available.  It is called moisture cure urethane.  It actually chemically bonds to the wood drying mostly by reacting with the water out the air.  It is solvent based, pure VOC, and smells terrible, worse than most oil based paint.  Do not confuse it with most urethane varnishes.  It is not widely available.  I have Sherwin Williams Rexthane on our family room floor.  It is only available in a very high gloss. We applied it 7 years ago.  We don't have children, but it has stood up to young Labs and other dogs continually, often several at a time playing exuberantly.  The ultra gloss is mostly gone, but it doesn't have any scratches, stains, discolored areas, etc.  It may also be available under the brand name Glitz.  It is very fast drying.  You can apply a couple coats in a day, and move the furniture back in the next.  It doesn't need a sealer, just good ventilation while you are applying it.  The smell is terrible.  Your child will not be scratching it unless it finds pointed sissors when you aren't looking.
Answer -
The product I mentioned is not water based.  It reacts with water.  It does not yellow with time.  Both water based and solvent based urethanes can be formulated not to yellow.  The line about water based products not yellowing sounds to me like it came from a salesman with water based material to sell.  I have worked as a chemist preparing urethane coatings.  I no longer work in that industry and have no economic interests to influence my answer in this case.

VOC is bureaucrat speak for for solvent.  It means volatile organic compound.  Perhaps it is meant to be more inclusive to include materials, such as styrene, that are a reactant in fiberglass resin, but much evaporates before the rest cures.  A solvent is something added to dissolve another material converting it to a liquid.  Water is the most common one.  Unfortunately, it will not dissolve many useful products.  For them, we use organic solvents.  Organic is used here in the chemical sense of containing carbon chains.  

Urethanes do not contain styrene.  I can't think of a volatile organic material that would be used in a urethane as other than a solvent.  Urethanes are made from very toxic, volatile materials, but they are very reactive and are tied up in a polyurethane.  

The materials you list are nasty compounds.  The truth is, some may persist for a long time, but in such a small quantity, as to be completely harmless.  Same with the nasty stuff the urethane is made of, except rather than being gone, it is changed into an inert material, no longer toxic.  

There is very little in the way of coatings that would harm a small child if eaten except the true lead based paint little used since the 30's.  There was not one iota of science showing any danger from the paints in the 70's when costs were forced up by a stupid law.  

Protect yourself by following the directions while applying.  When dry, relax, your child is safe.  

Answer
I think they are playing semantics games.  It has been 30 years since I worked in the coatings industry.  I never did much with latexes.  I think there was a different technical term for solvents when they were in the aqueous phase instead of solvating the the coating until the water evaporated.  So no, the nasty, toxic stuff such as N-Methyl-2-Pyrrolidone, Ethylbenzene, Oxirane, Hydrazine, Benzene, and Diethylene Glycol Ethyl Ether aren't technically solvents.  But they are there, and do evaporate.  Perhaps that is another reason for the more inclusive VOC.  

The moisture cure urethane has its own nasty warning labels.  It has more, but less toxic solvents that the above.  It also has some nasty unreacted chemicals in it.  However, they have a great affinity for water.  They are quickly converted to inert material by the moisture in the air.  Read the labels. Follow the precautions.  It is safe to use, but not abuse.  Note, if the label shows it contains any alcohol or oils such as tung or soybean, it is an inferior product.  The moisture cure urethane our performs anything except 2 package urethanes and epoxies, or enamels that must be baked.