>Read an Article for Home Inspectors that made several assertions I am checking out. (I'm a Home Inspector in real life and that's the job that supports my woodworking habit.)
The author claims lacquer has a "flash Point" well below room temperature. That if you smell lacquer in the hosue you should leave. Is Flash Point a clearly defined term? Do the manufacturers of lacquer tell us what the flash point is? Wouldn't it vary with brand and type? Isn't it difficult to get the vapor concentration high enough to sustain a fire?
He also states that if the finish on the floor is peeling its becasue they used lacquer as a base or primer coat for ureathane and that it will peel two years later. Any truth in this?
>"The author claims lacquer has a "flash Point" well below room temperature."
Flash Point: Is the lowest temperature at which enough vapor is given off to form an ignitable mixture with air near the surface of the liquid. The flash point is determined by one of two testing chambers: Open Cup (OC) or Closed Cup (CC). The testing apparatus consists of a small chamber in which the sample is placed; a thermometer or thermocouple to measure temperature and an open flame is passed over the sample as source of ignition. The sample is slowly heated until a �flash� happens. The open cup test results will have more applicability for the typical woodworking solvents than the closed cup result. A flash point of less than 100o F is considered highly flammable. Examples of flash points:
(1) Gasoline 45o F 43o C
(2) Acetone 0o F -18o C
(3) Benzene 12o F -11o C
(4) Ethanol 56o F 13o C
(5) Paint �thinner� 100o F 39o C
(6) Diesel 125o F 53o C
"That if you smell lacquer in the house you should leave." Maybe so.
"Is Flash Point a clearly defined term?" - See above.
"Do the manufacturers of lacquer tell us what the flash point is?" - Should be on the MSDS (if you get one).
"Wouldn't it vary with brand and type?" - Yes, it would depend on the amount and type of solvents used.
"Isn't it difficult to get the vapor concentration high enough to sustain a fire?" - No, not really. You need enough "localized" vapor concentration in the air above the solvent.
There could be some validity in the writers assertions. But like everything there's different degrees of correct.
If you walk in a room and the laq smell is so strong it takes your breath away, of course there could be a danger. But just to smell some laq in the air is not enough in my opinion. For example, you can smell perfume without it having any vapor concentrations in the air, likewise with laq.
The floor finish is a non-issue to me. I've never, in 35yrs, heard of a floor finisher using any laq products. But I've sprayed poly over laq sanding sealer with no adverse effects showing yrs after putting into service (furniture and trim not floors).
The flash point of laq products can be low, but the concentration of vapors has to be within a certain range to combust. Even then it needs a source of ignition. It will not spontaneous combust like oil finish on wadded up rags.
Their are some really knowledgable finishers over at woodweb.com on the finishing forum. You can probably get some more info over there.
>A flammable liquid in its liquid state will not burn. It only will ignite when it vaporizes into a gaseous state.
The issue is the solvent/thinner used in lacquer or contained in lacquer thinner. Once the thinner has evaporated, lacquer itself is not flammable.
>> The author claims lacquer has a "flash Point" well below room temperature.
It's true that lacquer thinner has a FP of about -10 degrees F. Which means it will combine with oxygen to form a flamable mixture at or above that temperature.
>>That if you smell lacquer in the hosue you should leave.
While concentration comes into play, if you smell it, it is best to get away until the source is known.
>> Is Flash Point a clearly defined term?
Yes, see above. You can google it under "Flash Point" for more detail.
>> Do the manufacturers of lacquer tell us what the flash point is?
Yes, it's required disclosure in the Material Safety Data Sheet (MSDS) which must be made available to the user.
>> Wouldn't it vary with brand and type?
Not by much although lacquer thinner can be different from different manufacturers.
>> Isn't it difficult to get the vapor concentration high enough to sustain a fire?
Depends if you are spraying it, brushing it, how large and area and the amount of ventilation.
Here is some good info on common thinners and solvents: http://asuwlink.uwyo.edu/~metal/solvents.html
>> He also states that if the finish on the floor is peeling it's becasue they used lacquer as a base or primer coat for ureathane and that it will peel two years later. Any truth in this?
The issue is with a lacquer based sanding sealer. A lacquer based sanding sealer contains stearates, or soaps, to make it easy to sand. Waterborne finishes and oil based polyurethane varnishs will not adhere well to undercoats that contain stearates. You should always ensure that any prior finish is compatable with the planned overcoating material.
There is no adhesion problem with polyurethane or waterborne finishes applied over fully cured lacquer. The lacquer should be thoroughly scuff sanded with 220 grit abrasive to provide a solid adhesion between the two coats.
But a caution, it is always risky applying a new coat of finish over a different type of finish. When it's a floor, it is even more risky as you don't know what else in the way of contaminates may be on the floor. It's best to always totally and agressively re-sand.
>I have to rethink "flash Point". I was thinking of the something along the lines of ignition temprature. Obviously lacquer won't ignite at a temperture below room temperture. It would have to have a Ignition source.
I do know of cases where they used lacquer for the first coat under ureathane. I don't know if it was sanding sealer. I doubt the top coat was water based.
Now that I have thought a while, I know of a house that had a fire because the floor finishers were spreading finish with a lamb's wool mop while smoking. A big "woof". They put the remaining fire out with an extinguisher and threw away their underwear. Had to repaint the interior and refinish the floors.
I am struggling with this because it affects what I can do or should do as a home inspector. Not sure its my job to sort out what the various layers of finish are on your floor. Suppose the finish is fresh and looks great, has not started to peel. Should I be held accountable because I do not notice that it was lacquer sanding sealer and the top coat was water based poly?
>The author claims lacquer has a "flash Point" well below room temperature. Likely true
That if you smell lacquer in the hosue you should leave. Crap You can smell the solvent components at orders of magnitude smaller concentrations than lower ignition limit or lower threshold for toxicity. For example toluene can be smelled at 2 parts per million.
Is Flash Point a clearly defined term? Yes It is the temperature at which the vapor above the liquid or formulation will generate enough vapor concentration to ignite.
Do the manufacturers of lacquer tell us what the flash point is? probably on MSDS sheet.
Wouldn't it vary with brand and type? Yes becasue solvent formulation will vary
Isn't it difficult to get the vapor concentration high enough to sustain a fire? NO!!
He also states that if the finish on the floor is peeling its becasue they used lacquer as a base or primer coat for ureathane and that it will peel two years later. Any truth in this? Could well be. Urethane is picky about what it will stick to.
