I have a roughed tip section from a 2/1 that never made it to a 2/2 rod, it's been laying around for about a year. I'm ready to bake the next rod and thought as long as I'm at the bakery, should I throw this tip section in as well to retreat it? The first time it was treated was in a pizza oven and I don't think it did as good of a job as the bakers oven.   (Pete Van Schaack)

I think if it were mine, I would certainly heat the already heated tip for a few hours at a low temperature, just to drive off some of the humidity.  Whether or not to cook it a few minutes more at high temp's is a judgment call you will have to make.  (Harry Boyd)

This sort of begs the question, "how many folks throw their rods in the oven, before applying the first coat of varnish or other sealer?" The presumption here is that the rod is absorbing moisture the entire time it's on the planning form.  (Jim Lowe)

If your there is more moisture in the air than in the rod, it is.  You can get the moisture low, for a while.  Nothing in varnish will keep humidity from adding moisture back into a chunk of wood (or grass, in the case of bamboo.).  We can slow the process down and keep things as dry as possible, but that's about it.  It's more a matter of moisture  management, I think, than moisture uptake prevention.  (Brian Creek)

So, Mr. Creek, are you trying to say that even though we take an inordinate amount of time to varnish our bamboo fly rods to keep them from absorbing moisture it doesn't really do what we think?  Do we varnish just to make our fly rods look pretty or is it to keep the moisture out from the occasional dunking from onstream foibles?  (Todd Talsma)

Naw, varnish is there for the poohbah's to critique. I thought Reed made it clear wax is better than varnish for repelling moisture.  (Rich Jezioro)

From all I have understood from past posts,  I claim no expertise, varnish only slows the absorption of moisture not prevent.  These present posts confirm that. Polly is the best, from past posts, but it too only slows. Nelsonite is a wood moisture stabilizer also. I do not know how well Mike Brooks formula works on moisture prevention.  It is that rapid absorption or release, I would think, would give the most problems.    (David Ray)

Varnish will keep water out, (to a point, obviously)but not moisture.  Drop the rod in the drink or fish in the rain and the varnish will keep the cane from slurping up water.  It's kinda like the concept of Goretex.

That's why Howard Miller and Sligh use plywood for panels in Grandfather clocks.  Humidity doesn't change their dimensions.  Have you ever cast a good rod by a quality maker that seemed 'soft?'  Moisture reentry.  It can be so bad you need to strip the varnish, bake the sections and start over. Had a Winston 7.5 footer a couple years ago that did that.  (Brian Creek)

It makes no difference whether or not one super-dries rod sections before varnishing.  While it's perfectly true that the cane absorbs moisture the entire time it's on the planing form, that moisture is ambient humidity and will be absorbed (as well as released) with or without the varnish.  This is the material's natural tendency to "breathe."  The process will continue throughout the life of the rod, and no varnish or sealer will stop it. Varnish retards the process, but will not prevent it.

The tip section in question (as presented by Pete in his email) is apparently already glued, and presumably, too, the cane was properly heat-treated prior to gluing.  So, unless the section has been stored in a particularly humid area, the tip should be good to go as is.  Heating it will do no harm as long as the temps are well below the melting point of the glue, but neither will heating make the tip better than it presently is.

The only issue of concern upon finishing a rod is that the sections must be as dry as possible prior to mounting the ferrules.  Cane shrinks and swells with ambient humidity, and mounting ferrules in high humidity is just begging for trouble when the rod dries out once again.  Apart from that, there are no humidity problems as long as one is within "normal" ranges. (This wouldn't include you, Harry.)  (Bill Harms)

As Bill says, cane has a natural tendency to "breathe."  Ambient humidity moisture will be absorbed/released with or  without the varnish. The process will continue throughout the life of the rod, and no varnish or sealer will stop it.

So why varnish? For starters, varnish retards rapid water absorption as in dunking the rod. It also helps keep dirt and grime from getting into the fibers. Lastly, it looks good. To protect the varnish, an occasional coat of carnuba is in order because of it's UV protection for the varnish and as an additional moisture barrier.

The tip in question should be fine without additional heat-treating.  Additional heat-treating could damage the adhesive. I would suggest putting the tip in a drying cabinet for a few hours/days and finishing it.  (Don Schneider)

It's just roughed planed cane, no taper bound in string. Was in the back of a closet and forgotten about. Not sure if when I first heated it it got to the 375 mark.

I think what I will do is heat the other two sections I have and compare.

This thread generated some very interesting topics, like waxing. Has anyone ever just waxed a rod without varnishing first? Like a very light 2 or 3 wt.  (Pete Van Schaack)

Look in the archives, there was a article in fine woodworking of a waterproof test on varnishes and wax and the only thing that truly waterproofed was carnuba wax.  (Patrick Coffey)

Moisture permeates all polymers and varnish is no exception.  Since water is a very small molecule, it squeezes its way between the bigger molecules of other substances.  So all polymers act like screen doors to one extent or another.  Some are a coarser screen than others and the thicker they are the slower the water penetrates the screen.  So eventually moisture will reach an equilibrium between the outside environment and the bamboo.  The varnish prevents rapid absorbing of gross amounts of water if you dunk your rod.  If you could find a material to plug the spaces between the polymer molecules  then you would  have a totally impervious coating.  But, alas, there doesn't seem to be available yet.   This is a bit of a simplification but I believe valid nonetheless.  (Al Baldauski)

What about Mike's Impregnating Sauce? I think he claims that it displaces all moisture  from the rod  (assuming you give it the full soak) and it won't get back in there.  (Larry Puckett)

Well, impregnating a cane section is an entirely different issue from varnishing.  And various impregnation process produce various results as far as moisture absorption is concerned.  (Bill Harms)

Interestingly enough, reading everything you always wanted to know about carnuba and were afraid to ask, on www.zymol.com, they make the claim that carnuba 'waterproofs' because the molecules swell when they absorb moisture, making the gaps between the carnuba molecules smaller than a water molecule.  (Larry Blan)

I've been through the humidity  learning curve this summer in Nashville, which is why I waxed my recent rods not long after curing the varnish in the (100 degree F) drying cabinet.  I  waxed with Restoration wax (apparently a concoction with very small molecules, created by the British royal museum for preserving very old objects) and sold at the local Woodcraft (though I don't see  it at woodcraft.com). I believed the marketing hype; it may only be carnuba. From reading the posts, I perceive that most makers wax rods for appearance, but it seems that a more practical reason is to seal out more of the moisture from getting through the varnish, as the years go by.  So I plan to wax at least once a season.  (Paul Franklyn)

While I'm sure the addition of wax helps retard moisture, I have serious doubts about the moisture stopping abilities of what we consider a coat of wax.  In the tests referred to in this thread, the wood was dipped in melted paraffin wax, not simply coated with carnuba and buffed to a high gloss.  I can see a very thick coat of paraffin helping much more.

For what it's worth, I wax my rods with the same stuff you do.  (Harry Boyd)

What Al has said - quoted below is true for all polymeric materials, varnish included which is a carbon-hydrogen polymer mixture. Polymers are hydrophobic - they absorb water.

"Moisture permeates all polymers and varnish is no exception."

Of course if one "soaks" the bamboo for an impregnated finish (IE: Orvis), then there is less space for the water molecules. Of course, the rod becomes heavier in this process because of the absorbed polymeric material.  (Frank Paul)

I think you meant hydrophilic.

Depending on the polymer, they will absorb anywhere between 1/2% to 3% water.  This means they will allow that moisture to permeate through to the bamboo and eventually reach equilibrium with the environment.  If you soak the varnished bamboo in a tub of water, it will eventually become saturated, albeit after a very long time.

If you store a rod at 70 degree at 50% RH  (air at these conditions contains 1% water) eventually the rod will reach a moisture content nearly that of its  surroundings.  (Al Baldauski)

I checked three dictionaries here at the cottage and did not find "hydroscopic", but I am sure that is the correct term. Hydrophobic is fear of water, so that is 180 degrees opposite. Anyway, I think we got it if I remember just a little Chemistry.  (Frank Paul)

Enough already; the word is hygroscopic.  (Jim Utzerath)