Extreme dryness and the Solid model

[teddon61]

Recently I had thirty aircraft on loan at the Veteran's Hospital in Milwaukee Wi, they were right next to the entrance and since we had such a cold winter in Wisconsin, with its resulting dry air, I noticed some hairline cracks on a number of the models.
I,m assuming that others have had this problem as well and wondering how you approach it. I put at least two coats of shellac on each model, followed by two coats of gesso, then paint at least two or more coats of acrylic on each.
I don't like to spray the aircraft with a gloss surface, although this seems to help, because I like the flat finish on the aircraft.
Is this an old subject? It seems significant enough to discuss.
Does anyone know if these hairline cracks continue to expand over time, or do they simply expand and contract depending on the humidity?
Ted Billings

[lastvautour]

All I know is that the change in humidity is the biggest factor. So far all those that I made in my basement that stayed there are all OK. The one that was relocated to the local museum developed hairline cracks that i have not addressed yet. I am thinking off using crazy glue(or similar) to ooze into the crack and then lightly sand and paint over. Of course with the satin finish on top, that will have to be replaced also. What is everybody else's experience. My older models that were moved from end of the country to the other all have some degree of cracking. Some were fixed using the crazy glue approach, but then they have not left my basement since soooooo!! only time will tell. The mahogany models from the Philippines do not appear to have this problem.

[teddon61]

Lou, there is a good chance that your basement has a rather steady humidity, that seems to be the key.
You mention mahogany as a wood of choice, it seems most comercial models are made from this wood, perhaps
they know what their doing.
I considered mahogany when I started carving the aircraft, now I wish I had paid even closer attention, but I just didn't
know how well it took the knife.
I keep two humidifiers going during dry spells in my home, just wondering if anyone else addressed this problem in a
more imaginitive way.
Ted Billings

[cliff strachan]

Hi Ted and Lou,

Just for what it's worth and I realize that my experience is markedly different from what you guys have described but my models which were built in '46 or before are still without cracks or other obvious forms of aging - something that has always concerned me and for which I can sympathise with builders like youselves who have done such fine work.

I built all mine as was the method at the time primarily using dope as the sealer/paint.

Cliff

[teddon61]

Cliff, thanks for the input.
Wow! Your planes are from the 40's, that gives me hope that I am building and collecting planes that future family members will enjoy for years to come, and of course, remember me.
Cliff, you don't mention if you take any extra care to control the humidty in the vicinity of the models, although Lou is probably right,a constant humidity at whatever percent is better than one which fluctuates wildly. There-in may be the secret.
Also using well seasoned wood, where most of the moisture is carefully removed either by kiln or airdried probably is important.
The challenge for me now is how to repair the damage already done, and hope the cracks already evident don't continue to enlarge.
Any ideas.
Ted Billings

[cliff strachan]

Hi Ted,

A constant level of humidity should solve part of your problem. However, I'm of the opinion that most of the difficulty is the rapid "change" in temperature and humidity. You say that your models were located right next to the entrance. Therefore I can well imagine that with the door opening and closing during a particularly cold winter your models were subjected to conditions similar to what we experience up here every spring. During the days our roads experience melt-water from snow and ice. This water after seeping into cracks later freezes during the nights. The subsequent cycle of melting and freezing results in "pot holes" playing havoc with roads. Of course, the models weren't subjected to water but the rapid change in humidity and temperture every time the door opened and closed and the likely rise in temperture due to the heating ducts near the door probably contributed to the problem.

Perhaps consultation with a furnature refinisher may come up with a solution of how to repair your models.

Certainly hope this might help.

Cliff

[teddon61]

Thanks Cliff. The models were right adjacent to the front doors of a very busy hospital, so the fluctuation was extreme.
I think a talk with a furniture maker will be a good idea.
I'm working on a Bristol Brigand right now, did any of them ever reach Canada? and did you see any of them? They do not have a
graceful appearance, but they look powerful.
Ted Billings