I introduce the subject of my choices for the best handle materials.  Keep in mind, the following is Stanley May’s ideas, preferences, and personal tastes of good handles.  It is by no means is an absolute.  I worked in the aircraft wheel and brake industry for 34 years in which I was a structural analyst/engineer.  I have explored the positives and negatives of most of the metal and composite materials used in today’s tactical knives.  It is exciting to me that today’s knife industry is using aircraft quality metals and composites to fabricate knife handles, frames, and blades.  Please note that this discussion is mostly concerned with handle structural considerations and not as much about appearance.

The below table summarizes the material properties of the major materials that are currently being used in handle production.  The metals have material properties that are pretty realistic and would be fairly consistent throughout the industry.  Carbon composites, G10, and Micarta material properties and qualities vary quite a lot.  For these material properties, I just took my best guess at what the average might be via some internet research I did.  Please do not take these as “gospel” because there is such a wide variety of qualities and constituents.  Another thing that clouds the issue of composite material properties is they are different in every direction (dimension).  So for the composites, I think it is worth noting the data is useful for comparisons and trends, but not much more than that.  Also note, I could not find reliable ultimate elongation values for the composites.  I am sure they are low.

Ftu = Ultimate tensile strength in psi where the material fails.  This is often used as a reference.

Fcy = Compressive yield strength in psi.  If you had an infinitely strong 1” x1” cross sectional bar, and you loaded it onto the given material (say a thick plate made of it), this is the point where the bar would sink into the given material and cause a permanent indentation in the material.  For lesser loads the material would return to its original shape.  For example, in titanium, if one were to load the 1” x 1” bar (1 in^2) onto a titanium plate, a load of 80,000 lbs would be required to begin permanent deformation.

Ult. Elong = The ultimate stretching you could do to a material sample when failure occurs.  For example in titanium, if you had a 1” tall test sample, you could stretch the sample an additional 0.08” (or a total length of 1.08”) when failure would occur.  If you had a 6” tall test sample you could stretch this bar 6 x 0.08” = 0.48” (or a total length of 6.48”) when failure would occur.  It is really the ultimate material strain the material can withstand.

Density = the material’s density in lbs/in^3.  i.e., 1 in^3 of titanium weighs 0.16 lbs.

S/W = the material’s strength to weight ratio, or simply the Ftu/Density.  The higher this number is, the more efficient the material is when trying to reduce component weight.

Italicized indicates an estimate

In my opinion, nothing beats the metals for handles/frames.  Metals generally exhibit more ductility (stretchiness without failing) than just about any other materials.  Carbon composites, G10, and Micarta are strong, are relatively brittle, and have very little ductility.  (Note I will now refer to these materials as composites)  So for example, a permanent deformation such as a gash accidently inflicted in metal tends to just produce the gash but nothing more than that.  Where the more brittle composite materials (low ductility) are more likely to create a crack, failure, or a crack which may grow into a failure.  In general, the more ductile metals can tolerate flexing and permanent deformations to a much higher degree than brittle materials.  It is for this reason that I prefer metals over composite materials.  To put this in different words, metals are more adapt to absorbing flexing, gashes, etc. without failing than composites, even though tensile strengths may be comparable.  

If handles are made of composites, I like a metal frame backing them up.  This provides a more ductile “foundation” for the composite, thus mitigating some of the brittle failure risk.

Of the metals, I really like titanium the best.  Titanium is an outstanding material.  Not only does it have great ductility, but for the weight, it is the strongest.  As shown in the table, it has a higher strength to weight ratio than steel or aluminum.  It is at the same time, nearly impervious to the water, salt, and many other environmental substances.  Steel oxidizes and so does aluminum to a lesser degree.  I have a large titanium aircraft component that has been in my garage for years, and all you have to do is dust it off and it looks like a brand new part; not a speck of corrosion or tarnish.  Titanium also can be anodized to provide different colors.  One down side of titanium is machinability.  It is a rather “sticky” metal making it somewhat more difficult to machine.  It is more difficult to get it to cut cleanly, it dulls machining tools faster, and usually requires slower machining speeds.  Techniques have been developed in the last couple of decades which have helped a lot, however if you asked a machinist which metal he would prefer to machine, he would likely say: Aluminum first, Steel second, and then Titanium.  For titanium aircraft parts, the parts are cast to size as much as possible.  Only the critical dimensions that need to be held to tight tolerances are machined (thus titanium machining is minimized).

My next choice would be stainless steel.  It can be made so it is even stronger than titanium, and is also very ductile.  For a given geometry, SS would be stiffer as well.  But the down side is greater weight.  Steel is almost twice as heavy titanium (for a given volume), so a knife with steel handles would likely result in a heavy design.  Resistance to dings, scratches and permanent deformation would be superior to that of both titanium and aluminum.  It is in my opinion; this benefit would not be worth the weight penalty that would be incurred when compared to titanium.  I do think it would make a very good frame material for the installation of composite type handles.  In this case I do not think the weight penalty would be as “costly”.

I am going to throw out regular, carbon, and mild steel due to the corrosion problems.  I believe maintenance of regular steel would be a headache.

Last on my list of metal handle materials is aluminum.  Although it is even lighter than steel or titanium, a significant strength reduction would be incurred.  This would result in handles that scratch, ding, and permanently deform much more easily than steel or titanium.  As with titanium, aluminum can be anodized to provide beautiful colors.  In fact, it is highly advisable to anodize aluminum for corrosion protection, and for the surface toughening benefit anodize provides.  An even better surface toughener is hardcoat, that makes the surface almost as tough as steel.  These coatings would definitely be very beneficial for light scratches or mild nicks.  The problem is anodizing and hardcoating layers are only 0.003” to 0.005” (approximately) thick.  They would not do much for the big dings or scratches because the metal below these coatings is still too “soft”.  I believe in the long run, anodized or hardcoated aluminum would not hold up (except in the collectors cabinet), and the appearance would suffer.  Also, once the anodize or hardcoat is broken through, the corrosion potential opens up.  Aluminum does corrode especially in the presence of water, salt, anything acidic, and many environmental substances.  And is there anyone who likes corrosion?  It is too bad they don’t make handles out of 2000 or 7000 series aluminum which are significantly stronger.  In summary, I think aluminum is just a little too “soft” to hold up to hard use otherwise I would rate it higher.

There are other metals that would be excellent choices for handle materials.  However most of them are exotic and very expensive.  If one wanted to make a very lightweight metal handle, magnesium would be a good choice; however, it ignites (very violently) and you wouldn’t want to get it near the ol’ campfire or strike it while sharpening the blade.  This is not one of my better ideas, and don’t try this at home.

Moving onto the materials I have labeled “composites” I think a very high quality carbon composite is an excellent material for knife handles.  This material has had a lot of development done by the aerospace industry.  Although it is brittle, its outright strength would mitigate some of the brittle failure problems.  It is extremely light weight so the design could be beefed-up a little, and still end up lighter than the metals.  If the quality of the carbon composite is good, I would not hesitate to buy a knife that uses this material for handles.

I would flip a coin to decide whether G10 or micarta is a better handle material.  These materials are very close to one another and the constituents are very similar.  In fact you might even argue they could be considered the same thing.  G10 is made with all kinds of fibers that are generally bonded together with epoxy.  Micarta is generally made with linen, canvass, or paper fibers bonded together in the same fashion as G10.  I don’t question they are great materials for grippiness, wet performance, and they do not corrode.  However in my mind, they are still brittle materials that generally do not have the high strength characteristics of a good carbon composite.  I totally like the idea of using these materials installed on a titanium or stainless steel frame, so they have a strong and ductile foundation.  Also, when I look at knives, I see a lot of lesser expensive knives made of G10.  So if you are on a tight budget, this material is not totally bad.  If acquired, I would not subject it to a lot of abuse or high demands.  An inexpensive G10 knife would also make a good backup for a primary knife you are taking into the woods, camping, hunting, etc.

At this point, I think it is worth comparing these metals/composites to those used in commercial and military aircraft.  Aircraft structural members such as skin, engine components, wheels and brakes, struts, wings, wing boxes, etc. are made of metals.  The metals give, bend, stretch, have high fracture toughness, have long fatigue lives, etc.  This is why primarily metals are used.  This is changing somewhat.  In some recent commercial aircraft designs, carbon composites are being used more and more because of their lightweight characteristic that is a premium for an aircraft situation.  A lot of this is due to the advances they have made in carbon composites.  However carbon composites still suffer from having different material properties in different directions.  They are weak in some directions but strong in other directions.  So if a member always experiences loadings in the same direction, the member can be made such that is has a lot of strength in that direction, and it is not terribly important that it be strong in the other directions.  A majority of an aircraft members have to support loadings in different directions, thus a metal still has to be used for these situations.  To my knowledge, G10 and micarta are not being used in the main aircraft members mentioned above.  To me, this aircraft comparison is an indicator of the best materials available for not only handles, but for any part you want to be structurally sound. If better materials were available, you would see them on aircraft.  In defense of G10 and micarta, it wouldn’t surprise me if they are using them in the aircraft interiors.

Lastly, a brief discussion of wood, bone, delrin, and plastic.  Wood and bone have the beauty appeal going for them.  This I cannot argue with, because for traditional pocket/fixed blade knives, the beauty of wood is incomparable.  There is something so special and beautiful about a knife with gorgeous cocobolo, snakewood, maple, walnut, etc. handles that cannot be matched by manmade materials.  The same thing is true for stag, appaloosa, ivory, natural and dyed bone, ram and buffalo horn, etc.  For me I favor the woods just a little more, but not much.  The problem with these materials is they tend to be brittle and not nearly as strong as the manmade materials.  If wood is used, I would say go with the hardest ones like snakewood or ebony.  They are going to resist denting and scratching better than softer woods; however on the other hand, the harder woods will tend to be more brittle.  Also wet environments should be avoided with wood.  My real wood recommendation is to go with the one you like the best.  For bone materials, brittleness is a big issue and they will chip and break more easily because of their extreme brittleness.  Their wet performance is very good however.  For bone type material I have a similar recommendation as to wood; go with the one you like the best.  For me, I do not like delrin and various cheap plastics, simply because if you are going to spend money on a knife, why not spend a little extra and get a natural or structurally substantial material.  In my opinion these materials are not very attractive or structurally substantial.

There you have it.  The world of favorite knife handle materials according to Stanley May.  I hope you found it interesting, however you can take this with a grain of salt, because they are my opinions.

So not including wood, bone, delrin, or cheap plastics, my final favorite handle materials list in order of my preference is:

1. Titanium – if you’ve got the money, go for it.
2. Carbon Composite – only if it is high quality, and you’ve got the money for it
3. Stainless Steel – heavy, but it is a very good material
4. Aluminum – assure it has strength equivalent to or greater than 6061-T6, and it is hardcoated. 
5. G10/Micarta – I love these materials, but for strength reasons I prefer #1 through #4.