Thread: Issues with natural materials

I don't think it is the level of humidity, but the fluctuations. Even if you put a solid piece of ivory in such environment it will crack. If you change the humidity slowly it would propagate from the surface into the volume and back and the whole object will expand and contract. If you change the humidity too fast the different expansions on the outside and inside can lead to mechanical stresses high enough to propagate a crack.

Alternatively, if you have two materials with different expansion coefficients bonded together then no matter how slow you change the humidity the mechanical stress at the boundary between the two will increase. With high enough stress you can break either the boundary or the material(s) depending on their relative strengths.

If you just leave it be the crack in the brush also means that further cracks are unlikely to develop. With the crack in place that part has room to respond to the mechanical stresses and it's harder for them to build up to the level necessary to create further breaks.

Since I don't know what I'm talking about I probably ought to shut up ........ but that never stopped me before so ..... On the ivory, if it is a 'tight' crack, I'd leave well enough alone and wait and see. Whatever stresses caused it may have been relieved and it may get no worse.

On the horn scaled Williams. I had a mammoth scaled Williams that began working it's way over to one side at the point until it finally was touching. I loosened the adjustable pivot bolt, moved the point to the center and tightened it up again. Once tight it was a bit right of center, but fine for opening and closing, and hasn't moved since. That's been months ago. Not sure if that would help, but worth a try.

On the heat/humidity issue ....... I had a crack develop in the back of a Gibson flat top with rosewood back and sides. I called Gibson in Montana to get a RA label. In speaking with the warranty dept the guy asked me what type of heat I used in the winter. I told him that me and the guitar have been in Florida for the past 10 years, and that I don't use heat at all.

He told me that they don't usually have 'problems' with guitars in that sort of environment. It is the instruments in the real cold climates that are exposed to the dehumidifying of heat sources drying the air out. Anyway ..........

You guys are probably right on the crack in the ivory. In my clime, as soon as I see a crack, I CA it. (usually caused by me!)!

It seems to stick to horn, ivory, bone great and keeps the crack from showing. Oh well!

Originally Posted by sharptonn

You guys are probably right on the crack in the ivory. In my clime, as soon as I see a crack, I CA it. (usually caused by me!)!

Wait, I'm confused now. I thought as soon as you find crack you smoke it

Originally Posted by gugi

Wait, I'm confused now. I thought as soon as you find crack you smoke it

That must have been back in the old days, Gugi! These days, most just superglue it!

Wondering this. I have been fortunate to buy razors from the East Coast of the USA on many occasions. We all know what Gugi refers to. So, I figure the vast majority of the ones I have bought had been super-cold and no 'heat' wasted upon them. In the shed, attic, basement, etc. Decent shape.
I do think an extreme change in HUMIDITY, combined with temperature, environment, etc might be to blame. If the materials are gently acclimated, no problem. Extremes (like when the family turns the heat up!), problem.