Merry Christmas to all and a problem

You don't include what is the temperature range where you are located, but unless it reaches at least 70F for several hours each day, it can take a while for finishes to cure.

Depends on how thick the finish is too. I *globbed* some oil-based poly on a gag gift. The thing is still out-gassing after a month of sitting in a

Just finished a project in the garage - warm when applied but cold at night. A week after the last coat - brought it inside - poly fumes !!! After 24 hours in 72DegF room - smell is virtually gone - Poly needs warmth and low humidity to cure properly.

John

Chuck B. wrote:

Thanks for the info. I'm in south Florida and the temp has been a bit cool lately but in the house it has been dry and between 70 and 75. I will just have to wait, I guess. I thjought maybe the poly was old or something. Would it help to buy some new poly and give it a very light coat if the original poly was "spoiled"?

I personally wouldn't. Give it time, reasonable temperatures, and low humidity conditions. If the original poly is not completely cured, the new coat could cause 're-melting' - ending up in a blobby mess. When it completely cures, the smell will go away. What you are probably smelling is the volatiles in the varnish evaporating.

I have used old poly that is years old, and have had no problems. This is my opinion, others may differ.

Greg G.

Thanks. I'll wait.

Does the smell really have anything to do with the curing? I thought the smell was from the solvents used to dissolve the varnish? Isn't the actual curing process odorless?

All finishing materials are a liquid with solids carried in it, the liquid is called a vehicle. When you apply it the solids stay where you put them and become solid as the vehicle evaporates. The majority evaporates fairly quickly, that is when you may call it dry, some are trapped in place and take time for them to come thru and evaporate, this is called the curing time and can vary with the type of material you are using and the weather condition, ie: Temp,Humidity, Dew Point and Baramoter Its as Simple as that, so while curing you have the vehicle slowly evaporating and thus the odor

Reactive finishes like varnish, cure by reacting with oxygen in the air. This occurs during the evaporation process and after. Once all the solvent has evaporated, the curing process may not be over. If coats are to thick the outer layer of the varnish will 'skin over' and prevent oxygen from penetrating to finish the curing process. The solvent may have already evaporated. Thus, if the varnish is to thick the layers will continue to cure even after all of the solvent has evaporated. This differs from shellac that does not react with oxygen. Once the solvent evaporates in shellac, that's it, its done.

not true.

epoxy and polyester resins are 100% solids they catalyze, not evaporate.

"this is called the curing time"

The curing time is how long it takes for OXYGEN to penetrate, not how long it takes the solvent to evaporate. (reactive finishes, like varnish)

I guess this was my point. :)

Thanks for the additional info. Both tables are still gassing some. It's been over a week. I'll get used to it.

OK so the oxygen is penetrating the varnish. So what do I smell? Something must be leaving the varnish (poly). I think I'll go read a book about it.

Read "Understanding wood finishing" by Bob Flexner. I refer back to this book all the time, it's awesome. Worth every penny. I think I bought mine at Barnes and Noble.

Thanks. On my way to the mall.

I screwed up. Usually I'm very patient with finishing.

The weather was suppose to turn cold and nasty so I was in a hurry with the computer desk top. I slathered urethane on the MDF. It was on the deck in the direct sun so when it felt 'dry enough' I slathered on another coat.

Damned thing stunk for weeks, took much longer than that to harden. Never again will I count on heat to cure/ dry/ harden anything except enamel.