Monday, May 18, 2015

A Guide To Stropping (or, just one blade enthusiast's opinion on the matter)



 Two sided 8" x 2.25" leather strop block, with polishing compound, by American Made Upgrades.
I get a lot of questions about stropping, so here it goes:

LETS TALK STROP SHOP
The strop is the most important and most used tool in the shop. Without it, your bladed tools will become worn and dull, requiring grinding to restore their pristine edge. Stropping works on pocket knives, kitchen knives, woodcarving tools, serrated edges, swords, straight razors, disposable razors, Xacto knives, hunting knives, scissors.... if it's sharp and can be held safely in your hand, it can and probably should be stropped regularly.

A perfectly good strop can be just a thin, short strip of leather. Or a really long, wide strip of leather with a hook or lanyard. Or it can be leather glued to a wood block, or many pieces of leather on a multi sided, hand carved work of art. Or a just a scrap of denim or carboard. The materials are less important than the actual skill of stropping. BUT, thick, undyed, unfinished, vegetable tanned cowhide works the best, is the most durable, and is a little more sophisticated than the back of a cereal box.

Leather strops were once in every home and workshop, but knowledge of their usefulness is less common these days. Everyone needs a good sturdy strop. Properly cared for, it'll sharpen like a champ for a lifetime.

Stropping works by polishing away only the tiniest particles of metal from the edge of your blade. Stropping is a finishing method. Repeat often, and your blade wont need harsh grinding nearly as often.

Be careful. If you are distracted or unskilled, a sharp tool will teach you a hard lesson, very quickly. Improper stropping can be dangerous.

A strop does not need to be as wide as your blade. A large strop is nice, but a small strop works fine on just about everything and stores/travels much easier. Strop in sections; you will always have to pay special attention to angled blades and strop in multiple sections, no matter how large your strop is.

Stropping a damaged blade doesn't work--your edge must be properly ground, and to a lesser extent, magnetically aligned. I recommend using a basic honing steel, commonly found in kitchen knife sets, to magnetically align the microscopic teeth on your blade, then strop your edge. For smaller woodworking and carving tools, or serrated edges, magnetic honing is not an option, but for straight edges it is very helpful. 

Strops take some breaking in.  They can be a little messy and slightly uneven at first, but they will become less flaky and more even with regular use.  A good way to break a strop in quickly is to strop a large, heavy, dull blade.  The smooth side of a butter knife works great.  You can press a little harder than you normally would and lean more of the backside of the blade against leather.  The weight and size will press the grain of the leather down, and press polishing compound deeper into the leather.

Two sided 8" x 1.75" leather strop block, with polishing compound, by American Made Upgrades.

PROPER PREPARATION AND PLANNING PREVENTS POOR PERFOMANCE
Clean your blade before stropping--a dirty blade will clog the leather, and can ruin it over time. Keep your strop dry and clean. It should only have polishing compound and metal particles on it.

Apply the compound like a crayon to the rough “flesh” side of the leather; do your first round of stropping on the flesh side. Do not apply compound to the smooth “skin” side; do your second round of stropping on the skin side to clean off leftover polish and metal particles from your blade, and to put a final polish on your edge.  (This is just how I do it; some people do it the other way around, applying compound to the smooth side and using the rough side to clean up leftover polish; others will put different polishing compounds on each side, or put the same polish on both sides.  There are many ways to load up your strop with polish.)

That chunk of compound should last you a long time.

Strop on a flat, hard surface, preferably the edge of a workbench or table. This can be greatly simplified by gluing two strips of leather to a wood block with contact cement; this makes a double sided, hard, flat strop that can be used on a less than ideal worksurface, as well as giving you some extra clearance between your hand and the workbench.

Place the fingertips of your non-dominant hand at one end of the strop to hold it steady, but do not hold the strop completely in one hand--it's dangerous. 

Basic Leather Strop: 8" x 2.25" with polishing compound by American Made Upgrades
HOW NOT TO DO IT 
Don’t strop like a Hollywood actor, with long, curving strokes, and a big flourishing roll at the end: that kind of silly stropping will turn a chefs knife into a butter knife. Poor technique will roll the edge instead of polishing it. Don't show off. It doesn't really look that cool anyway, and your blade will suffer for it.

HOW TO DO IT 
Pull the blade in short, straight lines, with the primary bevel flat against the leather. Imagine your blade edge as a "V" shape; lay the V flat on its side, then pull it gently and evenly across the leather, leading with backside of the blade and dragging the blade edge. Use very little pressure, no more than you would use to cut room temperature butter (not warm, not cold, just room temp). The fibers of the leather should depress slightly, but not enough to dip the blade egde into the flesh grain (which would roll your edge). Often, the weight of the blade itself is enough pressure, or even too much--finesse is key.

At the end of the stroke, STOP, lift strait up, do not roll the blade. Flip the blade over, strop the same section. Five passes on each side will do. For larger blades, strop in sections as wide as your strop, moving from the base of the blade to the point. For curved blades and clip points, strop in even smaller sections, be careful to maintain straight stropping lines.

When you have stropped all sections of the blade in both directions, flip the strop over so the smooth "skin" side is facing up. No need to add polishing compound to this side. Repeat the entire stropping process on the skin side; this will clean and put a final polish on your edge.

I do not recommend using an “X” pattern to strop the entire length of the blade in one stroke. This polishes your edge from a sideways angle, which allows fibers of the leather to project over your blade edge, resulting in an uneven or dulled edge. Short, straight strokes in multiple sections are the key to a finely polished edge.

HUGE two sided strop block:  16" x 4" with polishing compound, by American Made Upgrades.
POLISHING COMPOUNDS, CARING FOR YOUR STROP, AND OTHER MINUTIAE 
Don’t worry about polishing compound grits and colors too much. As long as your blade is properly ground and aligned, virtually any compound will work fine. Coarser grits do more work with fewer strokes, finer grits may take a few extra strokes. Don't over think it.

If you want your edge super-ultra-mega-splitting-hairs-scary kind of sharp, you’ll need to over think it. You'll need more than one strop and one kind of polish, multiple grinding stones, buffing wheels, and a lot of time. For the other 97% of us who just want sharp tools quickly and at a reasonable cost, my strops and polish should work just fine ;)

After many sharpening sessions, your strop will become caked black with metal shavings and polish. The leather will become hard and uneven if it builds up too much. Gently use a paint scraper to raise the grain of the leather and remove the crud (best to do it over a garbage can), then you can reapply the polish and start fresh. If you are cleaning your blades before you strop, you will very rarely need to do this. The skin side can be rubbed with a rag lightly doused in mineral spirits to remove some build up. 

Get a basic honing steel ($10) and a dual grit sharpening stone ($20), and learn how to use them properly. Combined with your strop, these three simple tools should be able to bring just about any edge to shaving sharpness--but only if you develop the skill to use your sharpening tools well. Used improperly, a sharpening stone and honing steel will ruin your tools. Do some research before you start grinding away at your edge.

Happy stropping. May your tools be ever sharp!

Signed, Dave from American Made Upgrades

POST SCRIPT
I am NOT a stropping authority. This is just what I've learned and what works for me. Feel free to ask Google all about stropping; you will find MANY other opinions. Stropping is an art--done well, it will make your blade shave arm hairs. Done poorly, it will dull your blade quickly. My knives and tools are pretty dang sharp, and I've researched it quite a bit and made many strops, but feel free to research the topic on your own. Google knows many things...

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