Bonding to Etched Blade

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grizzled gizzard

Joined
Aug 31, 2010
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I've heard that epoxy bonds best to etched steel.

Do you just try to scrub the oxidized layer away with solvent?

Am I missing something?
 
You may want to search glue wars, I think the best was a sandblast finish. I object is to provide a flat, clean , slightly rough surface for the glue to bond. I ways grind mine in two directions to create kinda check pattern. I keep thinking about where to put a sandblast booth.
 
Similar question, if you leave the scale on the tang instead of grinding it away will you get a strong bond? If cleaned with acetone and hit with a scotchbrite belt it looks like all the peaks and valley's of the scale would make for a strong bond. It seems like it would also save time and belts spent grinding of the scale.
 
I don't think I'd trust the scale bond. If you fool around with blades with scale, it tends to start flaking off, though some holds tightly.

Similarly, if you fool around with etched blades, they get scratched up quickly too. That's why I was wondering. There seems to be a fragile nature to the oxidized layer of steel. I think acra-glass soaks right into that layer. I clean the handle with acra-glass solvent, and it looks like it soaks right in, then slowly evaporates.

Maybe I heard wrong. What I understood is that chemical etching provides the surest bond.

In some of my destruction testing, the roughly sanded surface failed, and that's why I tried to pay attention when I heard about etching.

It makes a difference to me because I etch my blades anyway.

Is there a consensus about using liner material for structural advantage?

I will try to search for glue wars. Thank you for that.
 
grizzled gizzard said:
Is there a consensus about using liner material for structural advantage?
Click to expand...

I don't know. I like a thin G10 liner under natural materials, because in my brain it seems like a sure way to prevent moisture getting to the tang if the wood absorbs it... but that seems like a bit of a stretch and I can't prove it. Mostly, they look cool.
 
I don't believe the liner material does anything for strength and figure James said it right, in that it can look good. Frank
 
The failures that you have seen in the past may be from residue left on the blade by your acetone degrease. I learned this lesson the hard way on a gun receiver re-finish job. I was using a type of epoxy paint from Brownell's and it would just pop off a sand blasted finish using an acetone degrease. At the advice of the tech guys at Brownell's I added a degrease step. After the acetone I now spray the part liberally with Brake Parts Cleaner. This vastly improved the adhesion of the epoxy paint, so I have adopted this process on bonding the scales to a knife tang.

I have been buying the stuff in the red can at Wal-mart. The name on the can is Brakleen, and the active ingredient is TCE (Tetrachloroethylene).

Any good slow cure epoxy should bond well to clean steel that has been roughed up slightly. I'm not sure if the method of adding the roughness to the steel will make a difference, but if you are having failures I would bet it is an epoxy problem or improper degreasing that is causing the issue.

BTW the OP did not say if you are using pins of any type to improve the shear strength of the bond.

Good luck solving this issue.

Jeff
 
Thanks for the help, guys. I do appreciate it.

I always use pins or corbys, and skeletonize. I haven't had any failure other than testing, but I'm pretty new to this game, and maybe a little paranoid.

I don't understand why you wouldn't use acra glass solvent to de-grease. I thought using a tailor made solvent would be a no-brainer. I'm going to have to call Brownells. Maybe that is the trouble.

I guess I'll just keep putting liner on, even if it is just for looks. IMHO, it makes a knife look a lot different, and more "custom".

Any other thoughts are welcome.

Thank you.
 
If the surfaces are clean and prepared for gluing ( sanded to 120 grit ), the joint will be as strong as the glue in most cases.

Where glue joints fail most often is hidden in the end of the above statement.
If you make two perfectly flat surfaces, and apply a strong glue, then clamp then tightly together.....you will get a very, very weak glue joint....because there will be almost no glue in it.
All glues and resins have a membrane thickness that is optimal. It is usually a few hundredths of an inch.

Making a slight hollow in the tang and on the scales is one method to assure there is glue between the surfaces.
Another is to make swiss cheese of the tang.
Small divots drilled a tenth of an inch into the scales work, too.
 
Grizz

The guy at Brownell's told me that the TCE is a far superior degreaser than Acetone. I don't know if he was blowing smoke or not, but my adhesion problem went away when I changed. For what it's worth he first tried to sell me their degreaser at 3 times the price of the Brakleen, but then recommended that I just use the Wally World stuff to save money.

Not sure what the active ingreediant is in the Acraglass cleaner is as I've never used it. I'm using West Systems G-flex for handle glue up.

Jeff
 
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