The First Industry Specific Family Of Epoxy Adhesives For The Custom KnifeMaker

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When I first got started in the knife making hobby last year, like most folks I started lurking on some of the forums just to see how much knowledge I could gain strictly through osmosis. The thing that struck me the most was how much misinformation and downright bad advice was being given regarding the proper use of epoxy glue. I put together this little document in hopes of dispelling some myths along with providing some information regarding some very important concepts about bonding  things together with epoxy.


First things first....It's ALL about the surface

Before we get started with actual procedures, theres a couple of things one must understand about bonding things really is ALL about the surface! And probably the most important concept to understand is that of "surface energy" and the "water break free condition". Surface energy is best explainedusing the analogy of a waxed car. A car that has a fresh coat of wax that causes water to bead up can be said to have a low surface energy. Conversely, a car with no wax that allows the water to flow out or "break free" can be said to have a HIGH surface energy. What were after is surfaces that allow maximum possible wet out, or high surface energies. When our substrates have high surface energies, they bond much more readily, because the epoxy more adequately flows and covers the surfaces to be bonded. This is a VERY important concept to keep in mind, especially when bonding synthetics such as acrylic.



Surface Preparation

Probably the most misunderstood and incorrectly practiced routine in proper use of epoxy. It is VITALLY important that when gluing two things together that both mating surfaces are extremely clean and free of contaminants. and properly abraded to provide adequate "tooth" for everything to stick. However...and this is where most folks get it wrong...there is a VERY specific sequence in which this must happen, and its totally backwards from what most everyone thinks! The first step in proper surface prep is to degrease and decontaminate, which is best done with a Acetone or Denatured alcohol. Degreasing should be done in 2 stages. First thoroughly wipe the mating surfaces with a cloth dampened with the solvent, then do a second wipe down with a CLEAN DRY cloth to remove any contaminants that may have settled with the remaining solvent. Think of this as a 2 part "wash and rinse" cycle. Allow to dry thoroughly. Next we must abrade the mating surfaces to provide adequate tooth for the epoxy. Here's where I may leave most of you scratching your heads. If you can help it, do not use sandpaper to surface prep metal. Sandpaper is fine to prep wood, and even synthetics, but is not the most efficient of the abrasives to properly prep a steel surface. There are two really good methods of prepping metal; abrasive blasting using aluminum oxide  and Scotchbrite abrasive surface prep pads. For knife making I prefer abrasive blasting with 80-120 grit aluminum oxide, as I feel it provides the optimum surface of totally clean fresh metal with the proper surface pattern. Scotchbrite is a close second, and I prefer the 7447 maroon pads. The key here is that your abrading CLEAN metal...not cleaning abraded metal!!! This is essential to understand, as most folks get it the other way around. The reason being is that it is much harder to remove surface contaminants that have settled into an abraded surface than it is to remove them from a smooth one.The second thing to understand is that once the metal is cleaned and abraded...DO NOT UNDER ANY CIRCUMSTANCES re-wipe with a solvent. At this point there is absolutely nothing you can do to improve the condition of the surface. Applying more solvent will only increase the chance of contamination, because most readily available solvents contain some level of impurities. If you must clean the surface of the residual sanding dust, use an air compressor to blow off the residual debris...but DO NOT apply anymore solvent! Now you may go about the business of applying the mixed epoxy and clamping the mating surfaces for the allotted cure cycle.


Bonding Oily Woods

Many of the tropical woods, like Rosewood, Cocobolo, Teak etc....are quite oily in nature, and can present some issues when it comes to getting them to adequately stick to a substrate. BladeBond Ultra is formulated to provide excellent adhesion to oily woods. However, in order to get maximum performance out of the epoxy, a few rules must be followed. The key is to make sure that the surface of the wood to be bonded is wiped thoroughly with an aromatic solvent like Xylene, MEK or Lacquer Thinner prior to applying the epoxy. Avoid using acetone or denatured alcohol, as they evaporate much too quickly to adequately remove any surface oil. So, the procedure is to prep the wood surface with 80-100 grit sandpaper, wipe several times with the proper solvent and then bond as quickly as possible. Its best to get the epoxy onto the substrate(s) and clamped in place within 30 min. of the solvent wash to avoid surface contamination from oil in the wood


Bonding Synthetics

Plastics can present a whole different set of issues when it comes to achieving an adequate bond. The key to successfully bonding plastics is in understanding that many plastics have LOW surface energy (remember that?). In order to achieve an adequate bond with these materials we must do the best we can to manipulate the surface energy into something that will allow our adhesive to become more intimately aquainted with its substrate.  In many cases a simple abrading with sandpaper can go a long way towards achieving a better bond. However in extreme cases it is necessary to apply what is known as a "flame treatment". I sounds exotic and highly dangerous, but it's really fairly simple. Basically what you do is make a few quick passes with a propane torch over the plastic surface to be bonded, thereby imparting oxygen molecules into the surface of the substrate in order to increase the surface energy. The flame treatment can go a long way towards increasing the characteristics of the synthetic substrate to allow a much more "bondable" surface.



Measuring & Mixing

Proper measuring and mixing is imperative if one is to achieve maximum performance from any resin system. BladeBond in particular has a margin for error built into the measuring of each component. You can be slightly off in either direction and not notice any significant drop in performance. The most accurate way to measure equal parts of resin and hardener is with syringes. However, using yorker caps, one can get really close to equal portions with a little practice. Always mix on a flat surface, preferably using an implement such as a popsicle stick. Gently fold the two parts into one another to avoid trapping excessive air bubbles during the mixing process. Epoxies cure through an exothermic reaction, meaning they give off heat as they cure. So a couple of things to keep in mind; if you mix in a closed container like a small cup you'll contain the heat, and the potlife will be shorter. So if you do mix in a cup, pour the mixed resin out on a flat surface and allow it to spread out. This will greatly increase the pot life, allow any large bubbles to release, and provide a more consistent cure cycle. Also keep in mind that the smaller portions of A&B that you mix, the less margin for error there is. We reccomend that a minimum of roughly 3cc of each part be measured for a reasonable margin for error. Its false economy to thinkyour saving money by measuring tiny portions of each part. If the properties are comprimised because of an error in measuring, that is costing you much more than it is saving



Answers to Common Questions


What is the shelf life of your epoxy?

Our formulations utilize the latest in reactive diluent technology...there are NO solvents used in any of our products. What that means to you, is that if you store the unused parts A & B at room temperature, with the lid closed tight, the shelf life is virtually unlimited. The hardener may darken slightly (due to age), and/or the resin may crystalize (see answers below), but the performance properties will remain virtually unchanged. Additionally, we bottle our epoxy the day its ordered by the distributor to make sure you get the freshest product possible.



My part A resin has crystallized in the bottle, is it ruined?

NOPE---very common especially in cold weather. Simply microwave for 8-10 seconds at a time until it returns to liquid....good as new


Can I accelerate the cure of BladeBond Ultra to be usable in less than 12 hours?

Yes, If you have a small heating box where you can get the ambient temperature up around 125 degrees. BladeBond Ultra will reach a useable cure in about 2-3 hours. A plywood box and a hair dryer work great for force curing epoxy. If you need a quciker cure, use the Edge-15 formula.


Should I be worried about BladeBond Edge not being waterproof?

No...just be aware of it so you don't use it on items that will see prolonged exposure to water. Its highly doubtful that a knife...even a kitchen knife will see enough water exposure to ever compromise a bonded joint. However in the interest of full disclosure I felt it necessary to publish this. I want to re-iterate again...this is not just BladeBond Edge...its ANY mercaptan based hardener that has this attribute. If you're using a 5 minute epoxy, and the hardener has a horrible rotten egg smell...that's mercaptan, and it will NOT be waterproof.....only highly water resistant. I read a TON of bashing from the knife community on various forums about how Devcon epoxy gets soft under prolonged exposure to water. Look...I'm not a fan of Devcon, but this is NOT Devcon's fault! It's an artifact of a mercaptan based hardener.


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