Bamboo Tips - Tips Area
Blank Info - Protection

< Home < Tips Area < Blank Info < Protection

I have just glued and sanded my first blank and have ordered the ferrules.  Is there a problem sealing the blank with tung oil before it is ferruled?  Or, just keep it in a sealed PVC tube with desiccant until I get the ferrules?  (Dave Cooper)

Oil the rod; it will not interfere with fitting the ferrules, nor with finishing the rod (varnish or urethane) later.

Don't bother to keep the rod sealed with desiccant.  No matter what you do now, the rod with later equalize with the atmospheric moisture - no matter if it is varnished, urethaned, impregnated, whatever.  Nothing will stop equilibration (except completely sealing the blank in wax, but then you could never fish it).

You'll have an easier time fitting your ferrules if you let the rod equilibrate now.  If you keep the rod bone dry now, then fit the ferrules, you could run into problems when the male ferrule swells (too tight a fit).

Personally, unless you live in the Bayou, i never understood why folks make such a fuss over desiccant & dry boxes.  (Chris Obuchowski)

I resemble that remark!  I do live "in de bayou" and though I did for awhile, I no longer worry at all about keeping things in desiccants or dry boxes.  So far I don't think my rods have suffered too much.  (Harry Boyd)

My reason for using desiccant and a dry box is because that's what I've read in some of the rod building books. Having just finished rod #2 (or its rod #3 counting some practice planing & gluing that seemed too good to toss) and still on the front part of the learning curve all I know for sure is that  using desiccant and a dry box doesn't hurt. But from what I've read on the list, I am beginning to think that I may be able to skip the desiccant on the next one.  (Joe Hudock)

Actually, depending on what glue you are using, it might hurt.  some adhesives need a certain amount of moisture in the cane to work (read your adhesive label carefully).  (Chris Obuchowski)

Congratulations on your first blank. Apply the Tung Oil and leave it out of the tube. Wait a week before fitting the ferrules.  (Tony Spezio)

My concern would be that the glue bond to the bamboo would be weaker, no scientific evidence to prove it. (Henry Mitchell)

No scientific evidence here either, but also no shortage of opinions. I think there are at least 3 critical areas in a "glue-line" when bonding a ferrule to the rod section. There's the glue that fuses with the bamboo; the glue that functions as the glue-line itself between the two materials; and the part of the glue that's in contact with the metal surface. All these form a system, but the part that's most likely to fail is the mechanical bond with the metal.

I haven't had many failures, but sooner or later, we're all going to experience some. Each time I've repaired a loose ferrule the failure occurred at the point of contact with the metal. When I work the ferrule off, what I see on the bamboo station is glue that's perfectly intact and nearly as smooth as glass. By contrast, the inside of the ferrule is devoid of glue remnants.

So, what's needed is a bamboo surface that's able to accept whatever glue penetration is possible. But, a sealer works to defeat this because, with a sealer, no matter what kind of glue you use for the ferrule, the glue will bond to the sealer and not to the bamboo. Also, its strength can never be greater than the varnish/bamboo bond that lies beneath, and none of this can be as strong as gluing directly to the raw bamboo.

Secondly, we need a glue-line that's somewhat flexible so it can accommodate the stresses of: a) expansion/contraction as the cane swells and shrinks; b) different coefficients of expansion between the bamboo and the metal, and; c) sheer stress that constantly occur when casting.

Thirdly, because bonding to a metal surface cannot take place on either a molecular or a cellular level, we need to prepare the metal surface to maximize mechanical contact with glue. But, unlike the other "parts" of the overall system, the area of glue that actually contacts the metal is a film that's nearly microscopic.

It's a tough problem to resolve, and we've all had trouble figuring it out. Finding the right product is important, but probably even more important are the many steps of preparation. So, that's my "take," but for good advice, look to the many other makers who have some real expertise with adhesives.  (Bill Harms)

Just a comment to support Bill Harms on the bonding of metal to bamboo. I have found that a careful circular scoring of the inside of the metal ferrule to create circular micro-grooves provides bonding ridges for the adhesive.  It is good to create the grooves just before bonding so they do not oxidize; this provides a virgin metal surface in addition to the grooves for bonding. Additionally, it is good to clean the inside of the ferrule before creating the ridges to remove any oils and surface films from machining.  (Frank Paul)

IMHO, there's no problem with applying a coat of Tung oil to a rod section as long as the ferrule isn't fitted yet.  The oil will be removed from the ferrule station during the fitting process.  (Neil Savage)

Yep, that's what's needed.  (Bill Harms)

As soon as you finish removing the excess glue from a blank, apply your choice of protectant to the blank, be it tung oil varnish like Formby's, or straight tung oil, or shellac, calf slobber, or whatever.

Then cut the ferrule stations.  You now have mostly fresh, unsealed bamboo to which the glue may adhere.

The key, THE KEY to getting ferrules to stay stuck is cleaning the metal parts.  You can't get them clean with a burr, or a small file, or even a solvent.  Solvent will dissolve and help removed cutting oils, flux, and such -- so do that first.  Then actually clean the metal with gray ScotchBrite to remove any oxidation, films, etc.  Finally, wipe away the dust with a cotton swab.  Now the ferrule is clean and with a good fit, your glue will hold things tight.

I know that everyone says you're supposed to rough things up. But that's bad advice. Read Ralph O' Quinn on preparing a "water-break-free" surface for gluing at rodbuilding.org. (Harry Boyd)

I agree and don’t agree with your last post.

I wholeheartedly agree that ferrules MUST BE CLEAN in order to achieve good adhesion.  The bond strength to the metal ferrule is usually the weakest link and as they say, “cleanliness is next to Godliness”.  Especially as it applies to bonding metals.  Solvents only dilute oils and grease, so you have to wash with solvent multiple times to dilute the oils to an acceptable level.  It is better to follow the solvent wash with liquid detergent, then hot water.  This pretty much guarantees you washed away all oils.

Now that you have a CLEAN surface you SHOULD rough it up.  But roughing up the surface is a very variable concept.  What you need to do is rough it up microscopically with, as you say, something like ScotchBrite.  The idea is to increase the surface area so there is more to bond to.  A thorough ScotchBrite job will increase the surface are by about double, giving you double the total strength.

Roughing with a burr or file only provides a few scratches here and there which look ROUGH but don’t increase the surface area hardly at all.  The idea is to cover the ENTIRE surface with fine scratches.

The best abrasive to use for adhesion purposes is silicon carbide.  That’s what you have on Wet-or Dry paper.  Silicon carbide particles are very “pointy” and sharp providing good cutting action for microscopically deep grooves for good “bite”.  Aluminum oxide, found on most other sandpapers and most ScotchBrites, is a more rounded abrasive particle more suited to polishing which doesn’t give as deep a groove.

I would recommend 400 or 600 grit Wet-or Dry on a dowel to give a uniform “matte” finish on the inside of the ferrule AFTER the part is cleaned.   If you feel you need to wash out the ferrule afterward, use Acetone, then blow dry.

All of this I have learned from thirty years of making coatings stick to aluminum.  (Al Baldauski)

The detergent and water after the solvent make sense, I'd always thought that acetone or minerals spirits or alcohol were so volatile that they'd completely evaporate. Another step to add...

What I've been doing rather than ScotchBrite is to take a diamond burr on a Dremel tool to score the surface to be glued and making sure that the epoxy got into those little gouges so that once it set the epoxy has an actual "tooth" in the interior ferrule wall. I've yet to grind through the ferrule wall.... (Henry Mitchell)

I had a few ferrules come loose till I began using a Dremel to score the insides of the ferrules a little bit. It doesn't take much to make a sort of key way for the glue to bond. Roughing too much is problem, a good way to weaken to ferrules. Epoxies do bond best with an even surface but of the unstuck ferrules I've had problems with the epoxy always seemed smooth as a baby's you know what so I started roughing the ferrules a bit and no problems since.

Then clean them as Harry suggests with a solvent. I use RP7 as a lube in making the ferrules so metho works as a solvent well enough. Also, glue works best of all with freshly cut wood or cane so again as Harry says cut the stations immediately before mounting the ferrules.   (Tony Young)

You mention the glue bonding to the sealer. That would be true if precaution are not taken. I should mention, I tape off the ferrule stations and the area where the grip and seat will be glued on. No sealer or varnish is applied to this area. After the Formby's is applied to the blank, the tape is removed  then the ferrule stations are turned. I had assumed this is a known fact. to apply the glue to raw bamboo.

Glad you brought this up so that it could be clarified.  (Tony Spezio)