I have a woodworker that made a custom cabinet for me and when I picked it up it was still tacky from freshly sprayed lacquer. The cabinet was transported in the back of a truck with a moving blanket wrapped around it. While traveling on highway at 60 mph the cabinet started on fire. Is it possible that the fire started by combustion or would it require a spark from another source?

Although lacquer is highly flammable. Chances are a cigarette found its way to that blanket while in transport. I’ve done delivered too many and never had it happen.

Properly applied lacquer will dry to the touch in minutes. There is zero chance of spontaneous combustion with lacquer.

You seriously wrapped a blanket around a tacky cabinet? That would have pretty much ruined the finish right there.

If the finish was dry enough to not stick to a blanket then it's not going to be flammable. Just like gasoline, the fumes are what burns, not the liquid.

I'll bet the alleged professional woodworker you hired was neither.

What does he say? About the tackiness? About the fire?

Some areas of the country can only use water-base coatings. These would never combust.

The blanket would need to be soaked in thinner or lacquer to "spontaneously combust".

The air from the open road would not allow the chemicals to heat to spontaneous combustion unless the blanket was so soaked and wrapped up that air couldn't get in to allow the chemicals to generate heat.

For spontaneous combustion you need a finish material that cures through exothermic reaction. Boiled linseed oil is the usual prime suspect. Lacquer and lacquer thinner dry and cure thru evaporation. There is no heat in lacquer curing.

Kristine Heppler:

I am curious about the timeline in this scenario. Was the finish still tacky as the blanket was wrapped around the cabinet? I would think that in the space of time between when the finish was determined to be tacky, and the time it took to get a blanket and wrap the cabinet, any lacquer solvent would have flashed by that time.

I agree with Rich, that in order to still be tacky, that it was probably a linseed oil or one of the commercially marketed "oil finishes", where the thinners for these are usually one of, or a combination of, the aromatic solvents, which tend to dry slowly and thus the oil remains tacky.

I would hypothesize that if the finish was tacky, and you covered it with a blanket, a condition for spontaneous combustion was created, where the generated heat was trapped and possibly allowed to reach its combustion point. I would also offer up the possibility that if the wrapped cabinet was in an open truck, and you were moving at 60 MPH, you may have effectively "turbocharged" the spontaneous combustion that was waiting to happen.

Either that, or a meteor landed in your truck without your knowledge and set the thing on fire.

A real head-scratcher. I hope somebody had insurance.
TonyF

I was on a job site several years ago, a painters newbie helper was staining woodwork and took the saturated stain rags, balled them up and stuffed them in a garbage bag, it did not take long to start smoldering. Spontaneous combustion of solvent based products is a real thing.

I had a friend a few years ago have an employee stop and pick up a case of company t shirts from the screen printer. Employee threw the case in back of truck and half way back finished his cigarette and gave it a flick out the window. We he shirts smoldered and burned for the rest of the trip, stylzing all 100 shirts with burn holes.

If the finish was dry enough to not stick to a blanket then it's not going to be flammable. Just like gasoline, the fumes are what burns, not the liquid.