*OLD* Sig P51D kit...

Take a sheet of the balsa, knowing you can replace it, and flex it as far as you would a new piece those dimensions. If it feels brittle, cracks, or just breaks outright, replace all the balsa.

I "came into some money" once and bought a life-time supply of balsa. This was a long while ago. I lost two models to stress failures before it occurred to me that the balsa was dried out and was simply not good for a lot of applications.

I made maybe 15, 10" hand-launched gliders, got them balanced and flying good, and then used felt tip markers to make each look a little different. I walked around the neighborhood handing them out to the kids. I think some were still flying at the end of the summer...a little dinged up but still going.

Watch out for the old balsa that looks great...

Ken

I'll give that a try, but it sure looks and feels "new". Haven't had a problem with the 20+ year old PT-20 kit I built for my son several months ago.

Mine did, too. I thought it was really a good light grade of contest balsa. I first noticed it when I was cutting ribs and I decided the #11 was dull because the wood kept splitting.

I sharpened the blade, still split easy. Put in a new blade, split...then tried another piece of wood...started checking them. You know the wood is too dry when your Xacto stripper you have used for the last 55 years is now causing the blade to wander and the wood split.

It might be fine in your kit. A prudent person would check it.

Ken

Obviously you don't know how to operate such a sophisticated tool. :)

I've been called a lot of things, but never "prudent". It'll be a few weeks before I start in on this thing.. Gotta build a big workbench

1st. I don't think the kitchen table will support such a large build. :)

Well...I used to.

Of course, I used to be able to do a lot of things...like sleep all night without getting up to go to the bathroom...several times.

I have to tell this and it sounds like a joke...only I saw it.

I had an adult beginner modeler who wanted to build a 100" sailplane. I sold him the kit at my cost and told him to get an interior hollow-core door and build it on that. He said he had a lot of them.

I asked later how it was coming and he said pretty good but his kids kept screwing it up when he wasn't working on it. I told him to just slide it under the bed. He said, "I don't know how the hell I would do that!"

I figured his beds already had a bunch of stuff under them; mine does. Later, I was over at his house...yes...on the hall/den interior door, he had the wing laid out...vertically. I swore I would never tell that. But it has been a long time and I am not giving his name.

Did you hear about the real good home craftsman who made a door out of a table?

Ken

Waiting, with drumsticks in hand....

desmobob

Rim shot!

Say "Goodnight, Gracie."

"Goodnight Gracie."

Ken

Put a guitar case humudifier in the kit box for about a month and the wood will be just right.

DougSter

Hey desmobob, how ya doin'

Sometimes you can hardly get the CA to work on old, d-r-y kit wood. The humidifier idea is a good one. I was going to suggest storing the kit in the bathroom for a few weeks worth of shower humidity. I've never tried it but read it somewhere, so maybe it works and maybe not!

Hangin' in there, DougSter! Waiting for some flying (and motorcycling and bicycling) weather.... :-( And you?

Good flying, desmobob

hadn't thought of that.. I have one in my acoustic's case - I'll have to dig it up and give it a try... Will it take the musty smell out of the instructions? :)

I wonder how many guitar players are here -- I wonder how many uke players.

This dryness of wood is complicated. There is water in wood and there are natural oils. Different woods have different amounts of each at different times.

I tried to humidify some balsa and it didn't regain its resilience...but then, considering the weight of balsa, how much moisture could it have?

And the last point, I live at the edge of a southern South Mississippi swamp off Bollie Creek. I have hygrometers around here and everything stays near 50% rh inside, except for six weeks after the hurricane when we had 88 degrees and 77% rh. Dry, we never are.

Ken

"Green" balsa is among the heaviest woods out there due to the tremendous moisture content. That's why it's so light when dry... all the empty space where the water was! Balsa can hold a LOT of moisture.

Good flying, desmobob

I meant balsa that we use for our models. We wouldn't want much moisture in it or it would be too heavy. As for absorbing water, I remember life rafts and other floatation devices made from balsa.

Ken

The famous epic-journeying raft Kon Tiki was made of balsa logs lashed together.

Bill(oc)

I was referring to the wood we use in our models. Here's an excerpt from the SIG page, "Balsa Facts":

"The secret to balsa wood's lightness can only be seen with a microscope. The cells are big and very thin walled, so that the ratio of solid matter to open space is as small as possible. Most woods have gobs of heavy, plastic-like cement, called lignin, holding the cells together. In balsa, lignin is at a minimum. Only about 40% of the volume of a piece of balsa is solid substance. To give a balsa tree the strength it needs to stand in the jungle, nature pumps each balsa cell full of water until they become rigid - like a car tire full of air. Green balsa wood typically contains five times as much water by weight as it has actual wood substance, compared to most hardwoods which contain very little water in relation to wood substance. Green balsa wood must therefore be carefully kiln dried to remove most of the water before it can be sold. Kiln drying is a tedious two week process that carefully removes the excess water until the moisture content is only

6%. Kiln drying also kills any bacteria, fungi, and insects that may have been in the raw balsa wood."

Balsa is Spanish for raft, I think....

Bill, It's been a l-o-n-g time since I read Kon Tiki. Heyerdahl was an amazing man! I remember seeing a news item about him recently being found to have faked some "relics." I read another book of his years ago, "Fatu-Hiva," which was also a great read.

Good flying, desmobob

Probably will NOT take out that musty smell, since that's almost certainly from mildew (usually too MUCH) moisture.

I used to use those old clay guitar case humidifiers, the ones that you soak in water, drain and then put in the case during dry winter months. They usually work pretty well, but the humidity level can vary quite a bit as the clay drys out. Good enough for restoring some moisture to balsa. REALLY dry wood may never come back to ideal RH.

For musical instrument cases, firearm cases, precision tool cases, etc., I now use exclusively:

DougSter

"The OTHER Kevin in San Diego" wrote in message news: snipped-for-privacy@4ax.com...

Keep in mind; where the balsa has been stored is important. If it has been in a basement, or full heated/cooled shop, it will not dry out as badly. In an attic, or detached, closed up, hot garage. its moisture content is much more likely to get excessively low.

You can also do a lot to get that dried up balsa's moisture content back up. A fruit cellar, damp basement, even a large plastic storage box with a open bowl of water, will all put some of that moisture back into the wood.

As far as this whole discussion goes, where you keep your completed models has a lot to do on how dry the wood gets, in them. A closed up trailer in the sun has to rank right up there as one of the most "drying" environments that you could have. A powered fan could help that out, in the summer.

What's the difference how dry the balsa is? It dries out once assembled anyhow. It builds and works the same.

Damp and mildewed is a different story. But dry is fine with me.