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... 

[Ned Knepp]

 Nitrocellulose plastic is known for corrosive outgassing and even, sometime producing corrosive drops of liquid. There were a lot of guitars built with this produce used for binding as well pickguards  and the crumbling process I saw in the pickguard is repeated in the binding as well. As the movie industry found, it not the most stable or safe material every made. 

[RETROROD]

Several years ago, I was the caretaker of a '68 Byrdland. I soon noticed that when taking it out of the case after several days that there was a foggy film on the finish under and near the bound pickguard and on the gold-plated pickup covers. I would wipe and clean it but it would return again. Within a year there was a spot on the p'guard that looked like it was crystalizing or decomposing. I then removed the pickguard for good and bagged it.

I ended up sending it to Mirabella Restorations for an exact repro. Was very happy with his work!

It is a strange phenonomen, how these plastics react at different rates, almost like a life cycle and interact with the surrounding materials.

I think that Kerry's examples are on the extreme-side of what 'could happen' and a reminder that these instruments need some fresh air and sunshine, as we do!

Rod

[Topher Belknap]

Here is the MSDS for Nitrocellulose:

http://cameochemicals.noaa.gov/chemical/19047

That anyone is still using this stuff for anything is astounding. Please be careful and informed!

Some highlights:
Highly flammable. May ignite on contact with air or moist air.
May undergo a vigorous reaction with reducing agents, including hydrides, sulfides and nitrides, that culminates in a detonation.
Fire will produce irritating, corrosive and/or toxic gases. Inhalation of decomposition products may cause severe injury or death.

[Kerry Krishna]

Thanks Toper. I will never forget trying to reshape some Jim Dunlop Thumb picks so they actually fit my thumb comfortably. There IS a way to do this safely, ( boiling  water and taping up your thumb beforehand so it doesn't burn while setting) but I had no clue at that time. I had the pick in a pair of needle nose pliers, and was heating it over the stove element set on high. 

 Anyone wanna guess what happened, (and the pick was about 6 inches from the burner...)

[Paul Verticchio]

I bet it burned in an instant flash & it was gone.  I used to burn celluloid picks at tables between sets as an ice breaker. (: Drunk women were amazed, but hey, that was in the 70's.

Also, the stuff magicians use as "flash paper, is a cellulose based product.

So I'm NOT the only person who burnt the heck out of my thumb reshaping thumb picks(;  I learned the tape insulation trick on my second try (-:

Have a great one buddy (-:

[Ian Barker]

The issue is that nitrocellulose is an oxidising agent, which is why it can react with reducing agents (i.e. anything that is combustible).  It doesn't require a supply of atmospheric oxygen to create a fire, and in the right conditions (old, decomposing NC + fuel) it doesn't need any ignition source either. 

I have no doubt that this is exactly what happened to Kerry's guitars.

[Kerry Krishna]

Ian, If I had been camera aware at that time, and taken pics, few here would be saying 'maybe it's something else'. Ah,back then,  I was young and foolish, and still had my girlish good looks back then too... 

[Ian Barker]

....as Jamie and Adam would say!

[Mark Pollock]

http://makeprojects.com/Project/Chemical+Woodburning/827/1#.UMdFCKy...

This is an article about chemical woodburning, which produces a scorch mark without flame or heat. It also produces the smell of burning wood, known as smoke.

I would have found this earlier, had I been searching for "scorch" instead of "char".

I still contend that it is more likely to be a 20 year chemical process than a flash fire.

[Thomas James]

It does seem that if fire was present that any celluloid would have completely burned. I have seen some fairly nasty damage from off gassing.

[RETROROD]

I have cleared some rooms with MY off-gassing....

[RETROROD]

Excuse me if that was too light-hearted of 'drivel'....I do have a sense of humour.....even with off-gassing plastics!