Attaching new handle scales

[orvet]

Horn fluctuates too much with temperature and humidity changes to rely on epoxy alone, definately needs pins. I pin EVERYTHING now. In my very early days I didn't pin anything, some are still going strong others needed repair. Pins solves those issues.

I agree completely. Everything gets pinned unless there's an alternate method built into the knife of holding the scales on.

[OLDE CUTLER]

There are a few things I do that work best for me.

Sanding - use new sharp belts. The newer the belt the sharper the abrasive and the less time is required to sand something. Use a light touch and use a coarse belt to cut fast without heat buildup. Then smooth it down with finer abrasive.
I sand the surfaces to be glued with 32 grit on the back of the scale especially bone and stag to help the glue grab hold of the scale. I use a 32 grit 1/2" sanding drum on my Fordom and rough up the surface of the liner I am gluing to help the glue grab hold to the liner. Then clean it before gluing.

I clean everything with 91% to 99% pure isopropyl alcohol. It is inexpensive, ($1.59 at Krogers pharmacy) and it leaves zero residue. Petrolum products like lacquer thinner and acetone can still leave a very thin oily film. Alcohol is not oil base and leaves not oily film.

I use Bob Smith's 2 part epoxy. You can find the same adhesive under other names, they all seem to work fine. I use almost exclusively the 5 minute cure on folders because they say it is more flexible than the 15 and 30 minute cure versions. ("They" being the owner of USA Knife Makers Supply, a company that has the epoxy private labeled for them).

That is how I do things. It certainly not the only way, but it is the process I currently use, because it s the most effective and efficient way I have personally found.
My process evolves as I find new products and methods.

I have never had an issue using acetone as a degreaser prior to gluing. The brand of acetone I use is Sunnyside, and the label on the front of the can clearly states "no residue". Could be like a lot of things today, it is more highly refined than it used to be, like vodka, gasoline and others, with little or no impurities.

[orvet]

You are probably correct that the refining process may have changed from what it used to be. My experience in using acetone as a cleaner dates back to the late 1970s when I worked for a paint company and used a variety of cleaners and degreasers.

I probably remembered incorrectly, but I thought acetone was a petroleum-based product, however I find out it is an organic compound. I also did some googling on using acetone as a cleaner as compared to alcohol.
I found a couple of things that might be pertinent.
1 – Acetone is a solvent, it can actually dissolve things like certain plastics or nail polish one of the most common household uses of acetone. Alcohol the other hand does not have the solvent properties of acetone and cannot dissolve plastic or nail polish.
2 – A chemistry site said that it may appear that acetone leaves a residue on a service that it cleans, not because the acetone leaves a residue, but because the acetone dissolves some of the surface or contaminants on the surface and those are what leave the residue.

That is stretching my chemistry since I haven't had a chemistry class in over 50 years, but it kind of made sense to me.
I could see where acetone might be problematic if I used it to clean certain plastic handles, bone or certain woods. I can see where acetone could dissolve some chemicals in the plastics or wood that when have a detrimental effect on the adhesive quality of the glue one might use.

That to me, would be the main reason I would choose alcohol over acetone, based on this new (to me) information. That and the smell of acetone gives me a headache. What I do like about working with alcohol is that alcohol will bond with water and dry parts out quickly. Also from a safety standpoint; should you ever have a fire while using a cleaner, alcohol can be extinguished with water, I don't think acetone has that same quality, but I'm not positive.

I think as long as a person is very careful to abrade the surface, when appropriate and clean them well, whether with alcohol or acetone, they should have a very low failure rate of their adhesives. Paint thinner and lacquer thinner are petroleum-based products that do leave a film on surfaces when used as cleaners.


ADDENDUM
I appreciate the challenge that of researching the 'why' behind the reason I don't use acetone to clean knife handles before a glue up. It's good to go back in a rethink or justify the reasons why you do things a certain way especially when that way is based on information or experience that is decades old.
I learned several useful things in this, I didn't know that acetone does dissolve certain plastics, obviously something you need to be wary of. I also learned that the acetone these days doesn't leave any residue, which is quite different than my experience using it in the 1970s.
It's amazing how much a person can learn on AAPK from the other members!
Thanks for your post OC. It caused me to reevaluate and tweak if not change some long-held beliefs.

[OLDE CUTLER]

You are probably correct that the refining process may have changed from what it used to be. My experience in using acetone as a cleaner dates back to the late 1970s when I worked for a paint company and used a variety of cleaners and degreasers.

I probably remembered incorrectly, but I thought acetone was a petroleum-based product, however I find out it is an organic compound. I also did some googling on using acetone as a cleaner as compared to alcohol.
I found a couple of things that might be pertinent.
1 – Acetone is a solvent, it can actually dissolve things like certain plastics or nail polish one of the most common household uses of acetone. Alcohol the other hand does not have the solvent properties of acetone and cannot dissolve plastic or nail polish.
2 – A chemistry site said that it may appear that acetone leaves a residue on a service that it cleans, not because the acetone leaves a residue, but because the acetone dissolves some of the surface or contaminants on the surface and those are what leave the residue.

That is stretching my chemistry since I haven't had a chemistry class in over 50 years, but it kind of made sense to me.
I could see where acetone might be problematic if I used it to clean certain plastic handles, bone or certain woods. I can see where acetone could dissolve some chemicals in the plastics or wood that when have a detrimental effect on the adhesive quality of the glue one might use.

That to me, would be the main reason I would choose alcohol over acetone, based on this new (to me) information. That and the smell of acetone gives me a headache. What I do like about working with alcohol is that alcohol will bond with water and dry parts out quickly. Also from a safety standpoint; should you ever have a fire while using a cleaner, alcohol can be extinguished with water, I don't think acetone has that same quality, but I'm not positive.

I think as long as a person is very careful to abrade the surface, when appropriate and clean them well, whether with alcohol or acetone, they should have a very low failure rate of their adhesives. Paint thinner and lacquer thinner are petroleum-based products that do leave a film on surfaces when used as cleaners.


ADDENDUM
I appreciate the challenge that of researching the 'why' behind the reason I don't use acetone to clean knife handles before a glue up. It's good to go back in a rethink or justify the reasons why you do things a certain way especially when that way is based on information or experience that is decades old.
I learned several useful things in this, I didn't know that acetone does dissolve certain plastics, obviously something you need to be wary of. I also learned that the acetone these days doesn't leave any residue, which is quite different than my experience using it in the 1970s.
It's amazing how much a person can learn on AAPK from the other members!
Thanks for your post OC. It caused me to reevaluate and tweak if not change some long-held beliefs.

I should have added that the main reason I have acetone around at all is to clean spray paint residue and over spray from plastic lens eyeglasses. That's right, acetone does not attack at least the type of plastic used in the eyeglasses I have. My optometrist told me to use acetone after the second time I had to go in to have over spray removed at his office.