Off-gassing plastic and spontaneous combustion: Have you seen it?

[Kerry Krishna]

 A friend just posted an amazing photo on Facebook of an acoustic guitar that looks to be about 100 years old, with a giant pickguard that has seriously disintegrated and offgassed and badly stained the top. Maybe 1/3 of the wood of the top is stained darker. 

 I remember getting two electric guitars into my shop that the owners had no idea what had happened. Both axes had been in closed cases stored in closets, and had similar damage.Both of them, when I opened the cases, smelled heavily of smoke and chemicals.

 One the top and back binding were the controls were, had caught on fire, and melted itself right into the plastic fur of the case. The guitar had to be cut out. Lacquer/paint was extensively damaged in the two areas , and several other areas showed the binding turning to dark dust for several inches. The dust could be blown off, but lacquer surrounding it had been badly discoloured.   The front, sides, back for about one to two inches surrounding the burn, was bubbled, black and crispy, and blackened melted binding had dripped onto the side.   

The other guitar was vera similar except only had damage at the waist were the control panel was. Both cases when empty looked like someone had gently tortured them with blow torches in the affected sections. 

 In both cases, the total immediate history of the guitar was known, and neither case had been touched or even moved in over twenty years. 

I have talked to several Luthiers over the years who have never come across this and wonder how nuts I am for suggesting that it was spontaneous combustion. There is no doubt in my mind about it though. I wish I had been savvy enough back then, to take pictures. There would be no sceptics reading this... 

[Kerry Krishna]

I did'nt say that when the guitar that had to be cut out of it's case was on the bench, the burned sections were totally polluted with the yellow fur from the case, and some had melted right through to the wood.

[Mark Pollock]

I don't know about spontaneous combustion being the answer. Let's look at the facts, as stated.

- Guitars in cases for 20 years, without being moved or vented out.

- Cases, when opened, revealed heavy damage. The damage was centered around the former pickguards.

So, we can be sure that the damage occurred during the 20 year period. That is a LONG time. No ventilation, just celluloid sitting there getting more unstable day by day. I've had celluloid pickguard in bags go unstable and completely tarnish plated metal parts to the point that they crumbled, and that was over just 10 years of storage. In 20 years, I can see badly manufactured celluloid decomposing and interacting with all of the materials around it, bubbling into the probably non-natural fibers of the case, interacting with the glues of the plywood that forms the case, interacting with the fumes from the other plastics and finishes on the instrument, interacting with the cements used to stick things down and in place, having unknown amounts of heat and humidity in the environment - I can see this just happening over 20 years.

Also, spontaneous combustion means FIRE. Is the wood charred in this area? If not, then it was not a fire. If the wood was charred, then spank my bottom and send me to bed without any supper, and ignore my posting as well, but if it was not charred, then there was no fire. It still sounds like an absolute nightmare, and a reminder to air these instrument out once in a while. I shudder to think of guitars with decomposing tuner buttons locked in cases, with all those fumes just attacking everything in there.

[Kerry Krishna]

Mark, that was the point. it was all charred. Also the smell of smoke that I mentioned too... 

[Mark Pollock]

Wait, the WOOD was charred? That is, it was carbonized and black, with big cracks and the appearance that it has been in a fire?

I still don't buy it. There is not enough oxygen in a guitar case to sustain a fire hot enough to burn wood to that degree. Long term chemical decomposition in a contained environment causing breakdown of the cellulose in the wood, which is essentially a carbon-based cross-linked polymer.

Smell of smoke means nothing. I have cases that smell like smoke too, and have a nice bottle of artificial smoke that we use for making soup. Smoke is the product of a chemical reaction, and fire is just one kind of chemical reaction that produces heat and smoke. Smoke can also be produced without flame.

[Kerry Krishna]

Mark, the charring was all down to the wood through the finish, and I certainly am not going to argue with you about this. If you don't believe spontaneous combustion could be responsible, that's your gig.  Are there any other opinions out there? 

[charley erck]

Fascinating stuff. Mark, I could see the possibility of a fire that burned until the oxygen was consumed and then smoldered out.
Has anyone ever heard of a house fire caused by an instrument catching fire?

[Kerry Krishna]

The ones that I have read about don't fit that profile Charley. One guy figured that the 'fire' was actually smouldering for days and days on end. I don't think it possible that the guitar itself could not catch on fire, as there is no available oxygen in the case. 

[Kerry Krishna]

Also on both guiytars, it was the binding that had deterioerated, and not the pickguard. The pickguards on both guitars were intact.. Sorry I forgot to put that in.

[Joshua Levin-Epstein]

I don't have much of an opinion, but these are my thoughts:There is obviously a reaction going on, but it is a slow one (compared to fire). There is slow oxidation (rust, corrosion) and fast oxidation (fire). I would not be surprised if the detrioration of the binding released heat. I doubt the amount of heat would char (as in charcoal) wood but I'll bet it could stain and/or cause chemical reaction to the wood.

Also, it was not the lack of oxygen that stopped the reaction. It takes quite a case to be airtight. Think of the humidifier/flight cases that have valves on them for equalizing pressure.

The worst case of outgassing I've seen was the pickguard of a late 70s L-5. It ate the gold off the pick-ups and mounting bracket and corroded the strings sufficiently that several crumbled. The wood was untouched. There is a good picture of something similar in "The Fender Bass book" whick shows a pickguard on an old P Bass and what is left of the strings.

 

Joshua

[Ned Knepp]

The worst case of this sort of deterioration I've seen was on a Gibson mandolin that sat in the case for a prolonged period of time. Most of the pick guard looked like brown sugar. The mounting pins were almost completely corroded away and the fingerboard extension looked like it had been burned along the edge where the guard mounted. Of course, the frets were corroded green and pitted beyond help. In this case it was clear that the pick guard was the issue but I could see how it could have been mistaken for fire damage. 

I'm not saying that this is what happened to Kerry's guitars but the fingerboard really did look as if it was char on the edge. I think it was a chemical reaction between the ebony and the chemical gases from the fingerboard. Wood burns because of chemical reaction that occur with the application of heat so it isn't really required to have actual fire or even a lot of heat for this process to be duplicated if the right conditions are met. I think the combination of chemicals in the wood and from the fingerboard plus time degraded the wood in the fingerboard in much the same way a fire would have in much less time so it looked as if it was burned by fire quickly when it was actually "burned" by chemicals over time. One thing to note, however, is that the area of the fingerboard that looked like this was not overly large and I do not recall that it blackened my finger as I handled it over much as charcoal would have done, though it did flake off in very fine dust if it was rubbed.

[Dave]

Reading this thread reminded me of a (non-guitar) incident I experienced this summer. I can remember my 8th grade shop teacher explaining how to properly dispose of/store oil-soaked rages from wood finishing projects to avoid fire. But I guess I forgot that lesson this summer (it has been 44 years) while staining my deck.

After staining and wiping down the excess stain on one section of the deck, I threw the oil-soaked rags (the finish had rosewood oil in it) on the edge of the garbage bin and took a break to do some yard work in the front of the house. A brief time later (less than an hour), I started to smell smoke... but didn't make the connection.

When I finally did go back into the back yard, there was a column of smoke rising from the rags, which were charring and had melted a good divot into the edge of the plastic garbage bin.

This was the first time I had ever encountered "spontaneous combustion," so I did a little research on the net. Seems all it really needs is a chemical component (like an oil) that hardens/cures by oxidation, sufficient oxygen for the oxidation process to occur, and insulation that allows the heat of the reaction to build to an ignition point. Seems like linseed oil is a major culprit (and the rosewood oil in the penofin stain I was using). With sufficient oxygen, you can go to a full-fledged burn... if oxygen is limiting just charring and heat. I think I dodged a bullet, and will be MUCH more careful in the future.

My point is that, maybe a cased guitar (if the case fit tightly) could meet the criteria of insulation to allow heat buildup and a source of oxygen. The question would be, what is the component being oxidized?

[charley erck]

Yes! This is a perpetual problem, always warned about but seldom heeded until someone sees it in person.

Me included.I have seen tragic house fires caused by it. I'm always wary . I believe simply hanging the rags so that they air out and dry is enough to avoid said spontaneity. It's when they are wadded up that the heat can build up.Even so, I hang my rags so that any fire would fall harmlessly to the concrete floor.

How this relates to the cellulose oxidation would be interesting to hear about!