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Heat Treating - Dessicants

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What is the product that is placed in the sealed PVC tubes to keep the strips from dehydrating after they have been heat treated.  (Denis Dunderdale)

You will hear different opinions on the necessity of this step, but in my experience it matters not one iota what you try to do to keep the moisture out of the strips.  You can use pounds and pounds of desiccant to keep your strips dry before gluing if you like, but once you have stopped obsessing about this, the strips will seek equilibrium with the ambient humidity, no matter what you do.  And, too, in the end, there is not a varnish in the world that can prevent this process.

My point then, would be to heat-treat according to your favorite schedule, and then simply wish the strips well on the rest of their journey.  If you have a reasonably well controlled air conditioner in your shop, you will have no problems.  The point where you become uncomfortable working in the heat and humidity is probably the same point where the strips may also become a bit too high in moisture content.  But heat-treated strips quickly shrug off excessive moisture content in an air conditioned shop.

As a second consideration on this same issue, many of us have had later glue-failures when applying glue to strips that are excessively dry (especially a problem with URAC, which depends upon humidity for its curing process).  Then, too, if you are going to be using Epon, you will be subjecting the glued sections to a regimen of heat-curing which will also dry the strips.

Bottom line: if your shop is comfortable enough for you to work without perspiring, your strips will be OK too.  (Bill Harms)

Don't bother. Even if you keep the strips dry to the point of varnishing, they will eventually absorb moisture from the surrounding air's relative humidity.

If you're interested in reading about moisture in bamboo, I've attached a presentation that was given at this year's Corbett Lake Gathering.  (Ron Grantham)

I'll grant you that the strips will seek equilibrium with their surroundings, thus shrinking while heated and regaining some of their size after heating.  But is an attempt to keep the strips the same size the only reason to consider keeping strips dry?  I should think not.  For instance, here in the hot, humid South where Denis and I live, if one doesn't keep strips dry after heat treating pressing nodes becomes a never ending task.  (Harry Boyd)

It's pretty humid here in southern British Columbia as well. I soak my strips, then straighten the nodes, plane to size, then heat treat. Never had a problem. (I allow for the shrinkage in the taper.) The moisture tests were done because I was curious about how humidity affects dimensions. As far as keeping strips the same size? That can be a factor if you are trying to do an exact copy of an existing rod.  (Ron Grantham)

To answer your question, go to Hobby Town or Garden Ridge and search in the flower arrangement department and you will find desiccant made for drying flowers.  It works fine and has the litmus indicators in it to let you know when to 'bake' it to dry it out again.  It is finer crystals than the desiccant made for science laboratories, but kept in an old sock it will be easy to handle.

The PVC pipe is cheap and the desiccant is, too.  If build rods over a long period of time as I do, why not just store the strips in a low moisture container?   What could it hurt?  (Rick Crenshaw)