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A customer who took possession of his guitar a couple of weeks ago has just contacted me about problems with the French polish finish. It is a 12 fret L-00 with Red Spruce top and EIR back and sides. It is in a Calton case and I provided an SKB humidifier with it. I've always used Planet waves Humidifiers in the past. Anyway he tells me that the finish seems to be fading in places, exposing some scratches. As well he took it out of the case the other day and said their was some shiny sticky substance that had come out of somewhere and stuck some of the case interior to it. This SKB humidifier has an activating solution that has to be added to it when it is first used and he says he spilt a bit of it on the finish and it melted the finish where it spilt. I am suspecting that the activating solution is producing some type of fumes that are softening the shellac and causing trouble but find it hard to believe that SKB would use a solution harmful to finishes. I have told him to take it out of the case and leave the case open. As well I have recommended that he stop using the Humidifier. Has anyone experienced anything like this before. The guitar is In Calgary Alberta so I can't examine it myself. Fortunately he loves the guitar so that is good.

I haven't had your exact problem, but I have seen French Polish finishes on my guitars become dull in areas. I was finally able to track it down to the olive oil gasing or rising to the top from between the coats of shellac. Apparently I wasn't cleaning the oil off well enough between coats and some was trapped in between coats which later came up thus dulling the finish. A little polish and elbow grease cleaned it right up and it looked as good as new.

Good luck!

John

If I use oil I use Walnut oil and very sparingly. When I first learned to french polish 20 years ago I had this problem a few times but this sounds a little different. That ussually shows up within a few days while this finish was buffed out and had been sitting for a few weeks before being sent out. It is fading in places and sounds like it is getting soft and thus scratching..arvey38723.0293055556

I have French polished jewelry, trinket and keepsake boxes for over 30 years and guitars now for 4. I have never seen the shellac melt by any means other than a solvent extrem heat or exposure to vinyl (the elastimer in vinyl will soften shellac and lacqure alike)

Trap olive oil???: If extra virgin olive oil is used in conjunction with proper French polish padding technique you will not trap the oil between coats because you do not put down coats of French polish, you create one continious film by padding or amalgamating melted shellac into melted shellac. However if you do not use extra virgin olive oil or walnut oil the additives in the oil may infiltrate the shellac.

Dulling and exposing scratches?: This makes it sound like the shellac was hidding scratches. It is likely that any scratches that appear are wear. French polish is not a major wear protection. It will wear much faster than lacquer and dulling can happen just as polishing can happen. If an area is rubbed aginst a rough fabric over and over it will dull, if rubbed aginst a tight weave smooth fabric it will polish.

My guess, and this is just a guess is that some solvent in some form or another has come in contact with this guitar. It would need to be alcohol based, most likly.

MichaelP38723.4422569444

Further email from the client today and he mentions that there is actual staining inside the guitar from where a bit of the solution leaked and that the solution did actualy melt the finish where it dripped on it. He said that their is also a "darkening" (staining) inside the guitar at the same places where the finish has fadded on the outside. HE agrees that it sounds like something in the activator of the humidifier caused the problem. Has anyone else ever used one of thse.? On the up side, The client wanted to make sure It is clear that he loves the sound and playability of the guitar and really doesn't care much about how it looks as long as we can make sure it doesn'y get worse. At the same time though I do believe French polish provides better protection than people give it credit for.

Alkaline water solutions will dissolve shellac, as well as alcohol. Ammonia or borax are used in things like indellible ink to carry a bit of shellac and provide a measure of water resistance to the dried ink. I't possible thay used borax, or even alcohol, in the 'activator' as a fungicide. The staining of the wood suggests a mild alkali of some sort. Since FP is not as common as lacquer, which would not be effected by these things, it's possible that the humidifier makers haven't run into this problem and don't consider their product harmful.

I do not use a humidifier on my guitars. It is my opinion that it is better for the guitar to acclimate to its environment than to have an artificial environment created in the case that is different than the out side environment. The exception to this is for touring musicians. If going to many different environments over a short period of time then humidifying the case may be a necessity.

I live in a relative dry climate 30-45 average RH. When I sell to someone that lives in a wetter climate I ask them to leave the guitar in the case under half tension for a week after it has arrived to give the guitar a chance to acclimate. I have never had a return from going to a wetter climate. Now going to a dryer climate could be an issue but it is hard to find a dryer climate than mine

Micheal, we need these humidifiers up here in the north. It's impossible for a guitar to become acclimated to a climate that can have a 90% relative humidity in the summer and a 20% relative humidity in the winter.

_________________
Joe Breault
Merrimack, NH
Perpetual novice

[QUOTE=Alan Carruth] Alkaline water solutions will dissolve shellac, as well as alcohol. Ammonia or borax are used in things like indellible ink to carry a bit of shellac and provide a measure of water resistance to the dried ink. I't possible thay used borax, or even alcohol, in the 'activator' as a fungicide. The staining of the wood suggests a mild alkali of some sort. Since FP is not as common as lacquer, which would not be effected by these things, it's possible that the humidifier makers haven't run into this problem and don't consider their product harmful. [/QUOTE]


Plus i would guess that they manufacture these things figuring that 99.9% of the guitars that these will be put in are factory built lacqure or catalized resin finishes. Kind of a market driven design. That is my guess anyway.

Richard,
When you confirm that it was the problem write them and explain what happend. I bet they will be helpfull and who knows you could infuance the design of a new updated version. Engineering departments thrive on ECRs (engineering change request) and ECRs are mostly generated by people from outside of the engineer deparment reporting problems and or improvements.MichaelP38723.7218055556

Michael, I have already emailed them to ask about the problem and am waiting a responce. As far as Humidifiers go, I have one customer who despite my advice didn't get a Hygrometer or humidifier back when I didn't supply them. When He picked the guitar up it was around 90% humidity out, that winter his house dropped to around 12% (I know because I went there to check. Bridge pulled off, fret ends sticking out crack in top etc. There is no way you can build for those extreams so I build at 44% and provide a hygrometer and humidifier with all guitars. I personally don't use a humidifier as I keep my house between 30% and 50% and I don't tour. Most of my guitars are sold to touring musicians so they need them. Did sell to a fellow from San Francisco who claims he had no need of one though.