HOW TO USE A PASTED BALSA STROP

NOTE: This is a rough draft and work in progress. Expect errors. Expect typos. The content of this page is the work of @rbscebu and used with permission.

READ FIRST – IMPORTANT

1. Diamond pasted balsa strops are not for putting a shave-ready edge on a straight razor. They only make an already good shave-ready edge better.
2. Read this annex through in full before you start putting together and using your pasted balsa strops.
3. It is important that you follow this summary without any variation. Once you can get consistently perfect results from diamond pasted balsa stropping, then and only then should you consider making any alterations to suit your particular technique.
4. Most common question:
   
   Q. Rather than follow the instructions, can I [insert your proposal here]?
   A. You can do whatever you like. No one will punish you – just don’t expect the same perfect results.
   
   
5. These instructions are a summary of the relevant thread in the Badger & Blade Forum. They are not a substitute for reading the thread.
   
   https://www.badgerandblade.com/forum/threads/how-to-use-a-pasted-balsa-strop.473580/
   
   The thread covers the development of using diamond pasted balsa strops, explains why many of the things are done and answers most questions that you may have. It is strongly recommended that your read the entire thread. Take notes as you go as the requirements are modified and changed during the development. Then read it all again to check your notes.

Diamond pasted balsa strops are used for the final polishing of a straight razor (SR) edge to achieve the sharpest/keenest finish. It is may not be for everyone but there are many who are very happy with the results.
After an SR has a properly finished shave-ready edge (without using tape on the spine) from about an 8,000 to 12,000 grit (or higher) whetstone or 1.0μm lapping film, you can then progress to your diamond pasted balsa strop progression for that final polish. If that edge is then maintain on your diamond pasted balsa strops, you should never need to hone that edge on whetstones or lapping film again.

Note: Do not strop an edge on diamond pasted balsa strops if that edge has been stropped on a pasted hanging or pasted loom strop. Reset that edge’s bevel and progress through your normal honing without using any pastes before starting your diamond pasted balsa strop progression.

If the edge of an SR is not first properly well prepared on whetstones and/or lapping films, diamond pasted balsa stropping is not going to bring that edge up to perfection. Diamond pasted balsa stropping does not correct an imperfect edge, it only polishes an already shave-ready edge.

For the purpose of this summary, it is assumed that you know how to properly strop a SR without damaging the edge or the strop. If you do not know, learn and practice before you start using diamond pasted balsa strops.

You need three balsa strops (some make a fourth for a second 0.1μm balsa strop to be used as their hanging balsa strop). These are not normally available from a vendor so you will need to make your own. For instructions on how to make your balsa strops, see Annex II(A).

Three grades of diamond paste are required; 0.5μm, 0.25μm and 0.1μm. Diamond pastes come in either monocrystalline or polycrystalline. Polycrystalline works a little better than monocrystalline but either will do. If you do not know what type it is that you are buying, do not worry, just buy it – it will work. Diamond pastes may also be available in different concentrations, generally from 10% up to 50%. They all work just as well, however the lower the concentration, the easier they are to apply to the balsa. A concentration of about 25% is preferred by most. Diamond paste of 50% concentration will probably require thinning to easily apply. If you have a choice of packaging, choose the pastes in the 5g syringes. So little is used that a 5g syringe of paste should last you many years and the syringe makes it easier to measure out how much you want to apply. Diamond pastes are available online. Some online suppliers (2022) are:

• Ted Pella Inc. (US)
• TechDiamond Tools (US)
• Kemet (UK)
• Rubyvale Cut & Slice (AU)

They may also be available on Amazon or from Chinese suppliers through the likes of AliExpress and are quite acceptable. Just be sure that you are getting the required micron sizes. Most do not go smaller than 0.5μm or 0.25μm and you want 0.5μm, 0.25μm and 0.1μm.

One or more of these is required when applying the diamond paste and may be used for wiping the blade clean between stropping with different sized pastes.

Three or more pieces of chamois, either natural or synthetic, at least one for each micron size. They are used moist to wipe the blade clean between stropping with different sized pastes. After each use, each piece should be washed and thoroughly rinsed to remove traces of diamond paste.

You will need some method of lapping the working surface of the balsa strops flat. This will need to be done before you first apply paste to your balsa strops and every time that you renew a balsa strop’s diamond paste. A suggested cheap method is to use a 300mm (12”) x 300mm (12”) or 380mm (15”) x 380mm (15”) x about 6mm (¼”) thick SMOOTH and PERFECTLY FLAT glossy ceramic or marble tile and a sheet of sandpaper of about 220 to 400 grit. You can check that the tile is smooth (no imperfections) and perfectly flat by closely observing light reflected off the surface. The tile should be available from most home improvement/tile stores or some hardware stores. The sandpaper should be available from most hardware/paint stores. If you have difficulty in holding the sandpaper in position on the tile while you lap the balsa wood, you may also need some Loctite or 3M type spray adhesive or similar. This should also be available at most hardware stores.
You will also need a small (25mm (1”) to 50mm (2”)) stiff nylon brush or bronze/brass wire brush to clean the sand paper.

For your first lapping of clean balsa wood strops, you can just use one sheet of sand paper.

For subsequent lappings of already-pasted balsa strops, you can also just use one new sheet of sand paper, provided you lap them in order of; 0.1μm first, 0.25μm next and 0.5μm last. If done this way with just one sheet of sand paper, never use that sheet again to lap your balsa strops. This will help prevent cross contamination of diamond particles on the balsa strops.

If you wish to reuse the sand paper for subsequent balsa strop lappings, you should use three separate sheets of sandpaper, one for each micron size of diamond paste. Write the micron size on the back of each sheet and only use the sheet for 0.1μm on the 0.1μm pasted balsa strop etc.. This will help prevent cross contamination of diamond particles on the balsa strops.

The top (working) surface of the balsa wood must first be lapped perfectly flat before pasting and using. Even if it looks flat and smooth, it is not and must still be lapped flat and smooth. If you cannot easily hold the sandpaper steady on the lapping plate while lapping the balsa wood flat, spray the back side of the sandpaper with Loctite or 3M type spray adhesive. Just a faint dusting of the adhesive works best.

Carefully position the sandpaper on the lapping plate ensuring that it is smooth and perfectly flat on the plate. Make sure the sandpaper goes on smooth and tight with no bubbles or debris (not even a hair) under it and no wrinkles. This is extremely important.

Using a soft lead pencil, very lightly draw a cross-hatch pattern of about 20mm (¾”) squares on the upper surface of the balsa. Now place the balsa face down on the sandpaper and carefully rub, rub, rub. When you see no more pencil marks, you have created a whole new surface, obviously the balsa is now as flat as the sandpaper. So, the flatter, the better.

While sanding, balsa wood dust will start to build up on the sand paper. This build-up will be detrimental to the finished surface of the balsa wood. Use the stiff nylon or bronze/brass wire brush to remove this balsa wood dust from the sand paper as you lap the balsa strop. If re-lapping a previously pasted balsa strop, make sure that thoroughly clean this brush between use for different grades of diamond paste to help prevent cross contamination.

Once finished, wipe and dust off all loose particles on the balsa wood. You do not want anything to contaminate your diamond pastes.

Each of your three balsa strops will need to have diamond paste applied to their top (working) surfaces: 0.1μm on the first balsa strop followed by 0.25μm on the second balsa strop and finally 0.5μm on the third balsa strop – strictly in that order. You want the diamond crystals embedded into the balsa, not rolling and scooting around on top of it.

It only takes a little bit. If you think you got enough, then you probably have about 3 times too much. You MUST NOT have a coating on the balsa. You want a very small amount, rubbed into the balsa, about the size of a BB pellet or a bit less. You can thin your paste down with a light spray of an alcohol based hand sanitizer. Spread it around and rub it in very well first with your finger tips and then with the ball of your hand in a circular motion. Once rubbed very well in, use a piece of clean t-shirt and rub the balsa surface in a circular motion to remove the diamond paste. Continue doing this until you cannot see any further diamond paste being picked up by the t-shirt. You then and only then have about the right amount of diamond paste on your balsa strop.

Now, this is very important. It does not matter if you contaminate a coarse grit with a finer grit, but you must NEVER let a finer grit become contaminate a coarser grit. The way diamond pasted balsa stropping works is each stage makes scratches in the steel, the size of which is determined by the paste’s grit size. Each grit must totally eliminate the coarser scratches of the previous grit, replacing it with its own finer scratches. Even just a few crystals of a coarser grit basically ruins your result for the finer grit. So, always clean your hands thoroughly and use a new piece of t-shirt when going from grit to grit. Label each balsa strop with its paste size by writing the size on the ends of the substrate using a Sharpie (marker) pen.

There are three basic types of laps or strokes used in this balsa stropping. They are the; standard lap, pull stroke and short X stroke.

Note: The photos below are taken with the balsa strop on a bench due to a lack of free hands to take a photograph. You will of course be holding the balsa strop in your non-dominant hand.

The following are instructions for one standard lap:

1. Holding the razor in your dominant hand, you start by placing the blade’s spine on the balsa at one end and gently lower the edge onto the balsa (see Fig. II 1).
   
   Note: Always ensure that the spine and edge remain in contact with the pasted surface of the balsa during a standard lap.
   
   
2. You then slide the blade to the other end of the balsa stopping about 25mm (1”) to 50mm (2”) before the end (see Fig. II 2).
3. Keeping the spine on the balsa, you then flip the blade over to its other side, being careful to very gently lower the edge onto the balsa (see Fig. III 3).
4. Then slide the blade to the other end of the balsa stopping about 25mm (1”) to 50mm (2”) before the end (see Fig. II 4).
5. Keeping the spine on the balsa, you then flip the blade over to its other side, being careful to very gently lower the edge onto the balsa (see Fig. III 5). Now you are ready to start your next standard lap.
   That completes one standard lap.

The following are instructions for one pull stroke:

1. Holding the razor in your dominant hand, you start by placing the blade’s spine on the balsa and gently lower the edge onto the balsa (see Fig. II 6).
   
   Note: Always ensure that the spine and edge remain in contact with the pasted surface of the balsa during a pull stroke.
   
   
2. You then slide the blade across the balsa about 20mm (¾”) (see Fig. II 7), ensuring that the spine and edge always remain in contact with the pasted surface of the balsa.
3. You then slide the blade across the balsa about 20mm (¾”) to its previous original position (see Fig. II 8), ensuring that the spine and edge always remain in contact with the pasted surface of the balsa.
4. Keeping the spine on the balsa, you then flip the blade over to its other side, being careful to gently lower the edge onto the balsa (see Fig. III 9).
5. Then slide the blade across the balsa about 20mm (¾”) (see Fig. II 10), ensuring that the spine and edge always remain in contact with the pasted surface of the balsa.
6. You then slide the blade across the balsa about 20mm (¾”) to its previous position (see Fig. II 11), ensuring that the spine and edge always remain in contact with the pasted surface of the balsa.
7. Keeping the spine on the balsa, you then flip the blade over to its other side, being careful to gently lower the edge onto the balsa (see Fig. III 12). Now you are ready to start your next pull stroke.
   That completes one pull stroke.

The short X stroke is best described with a video (see Vid. II 1). The following is a video for two short X stroke:

TODO: fix embedded video

[MEDIA=youtube]KQiR8fvv84Y[/MEDIA]

The above video (Vid. II 1) shows two complete short X strokes.

Once you have finished your honing on a blade (either whetstone or lapping film), normally on about 12,000 grit or higher and the edge is shave-ready, it is time to start your balsa stropping progression. First you must thoroughly wash your hands and wipe the blade totally clean so that there are no particles on the blade or your hands from the previous honing.

Hold the balsa strop in your non-dominant hand while using and the SR in your dominant hand to strop. Do not use the balsa strop on a fixed surface, only in hand. All balsa stropping is done with edge trailing. Half way through the stropping of a blade on a balsa strop, end-for-end the balsa strop. This is to average out the wear on both the balsa strop and the blade.

The following standard laps are for high carbon steel blades that normally have a hardness of about 60 RHC or a bit less. If your blade is of say a VG10 type stainless steel that have a hardness approaching 65 RHC, increase the standard lap count only (except on the hanging balsa strop) by about 25%. For very hard specialist steel blades that can have a hardness approaching 70 RHC, increase the standard lap count only (except on the hanging balsa strop) by about 50%. The count for pull-strokes and short X strokes does not change for different steels.

During the stropping on each balsa strop, you will need to perform some “pull strokes” using the same pressure that you used in the stropping. Pull strokes are used to strip any microscopic burrs that may have developed on the edge. If you are worried about cutting into the balsa wood, you can include a small edge trailing movement with each pull and push.

During the stropping on each balsa strop, you will need to perform some “pull strokes” and “short X strokes” using the same pressure that you used in the stropping. The short pull strokes remove any microscopic burrs, wires or fin-edge that may be developing. The short X strokes do the same but also put a microscopic X scratch pattern on the bevel that tends to increase shaving comfort.

After many shaves, you may wish to try a full progression again, just to see if there is any improvement.

Start with stropping on the 0.5μm pasted balsa strop. Hold the balsa strop about horizontal, pasted side up, with your unsupported non-dominant hand with one end of the balsa strop pointing towards you and the SR in your other hand. Always strop spine leading so as not to cut into the balsa. Using pressure of about twice the weight of the blade, the stropping sequence should be:

1. 15 standard laps
2. 3 pull strokes
3. 15 standard laps
4. 3 pull strokes
5. end-for-end the balsa strop so that the end that was pointing towards you is now pointing away from you
6. 15 standard laps
7. 3 pull strokes
8. 15 standard laps
9. 3 pull strokes

Wipe the blade clean with a piece of moist chamois (or clean piece of t-shirt) and then thoroughly wash your hands to remove all possible traces of the invisible 0.5μm diamond particles from both the blade and your hands.

By now your edge should be tree-topping some hair at about 6mm (¼”).

Next strop using the 0.25μm pasted balsa strop. Hold the balsa strop about horizontal, pasted side up, in your non-dominant hand with one end pointing towards you and the SR in your other hand. Always strop spine leading so as not to cut into the balsa. Using pressure of about one and a half times the weight of the blade, the stropping sequence should be:

1. 15 standard laps
2. 3 pull strokes
3. 15 standard laps
4. 3 pull strokes
5. end-for-end the balsa strop so that the end that was pointing towards you is now pointing away from you
6. 15 standard laps
7. 3 pull strokes
8. 15 standard laps
9. 3 pull strokes

Wipe the blade clean with a piece of moist chamois (or clean piece of t-shirt) and then thoroughly wash your hands to remove all possible traces of the invisible 0.25μm diamond particles from both the blade and your hands.

Next strop using the 0.1μm pasted balsa strop. Hold the balsa strop about horizontal, pasted side up, in your non-dominant hand with one end pointing towards you and the SR in your other hand. Always strop spine leading so as not to cut into the balsa. Using just the weight of the blade as pressure, the stropping sequence should be:

1. 15 standard laps
2. 3 pull strokes
3. 15 standard laps
4. 3 pull strokes
5. end-for-end the balsa strop so that the end that was pointing towards you is now pointing away from you
6. 15 standard laps
7. 3 pull strokes
8. 15 standard laps
9. 6 short X strokes

By now your edge should be tree-topping most hairs at 8mm (⅜”) to 12mm (½”) or better with you hardly feeling it happen.

The last part of the balsa stropping progression is done again with the 0.1μm pasted balsa strop. Hold the balsa strop at one end with your non-dominant hand between the thumb and one of your fingers. Allow the balsa strop to hang downwards. You will be stropping vertically up and down while the balsa strop swings in the air. The purpose of this is so that your stropping pressure will be less than the weight of the blade. When stropping, try and use such light pressure that the balsa strop doesn’t swing more than about 25mm (1”) to 35mm (1½”) away from the vertical. You also need to ensure that the spine always remains in contact with the balsa surface.

This method of stropping on a hanging balsa strop will take some practice to perfect. Always strop spine leading so as not to cut into the balsa. Stropping vertically up and down, the stropping sequence should be:

1. 15 standard laps
2. 6 short X strokes
3. 15 standard laps
4. 8 short X strokes
5. end-for-end the balsa strop so that the end that was pointing towards you is now pointing away from you
6. 15 standard laps
7. 10 short X strokes
8. 15 standard laps
9. 12 short X strokes

Wipe the blade clean with a piece of moist chamois (or clean piece of t-shirt) and then thoroughly wash your hands to remove all possible traces of the invisible 0.1μm diamond particles from both the blade and your hands.

Your SR is now ready for stropping on a clean leather strop and shaving. If you will not be stropping and shaving with this SR the same or next day, protect the blade with oil or petroleum jelly as normal.

After your first shave off diamond pasted balsa strops, dry and clean the blade. Then put the SR through another full balsa strop progression (sections II 4.3 to II 4.6 above). Repeat this after each shave until you notice no further improvement in the shave quality of the blade’s edge.

Once a blade has been through the normal diamond pasted balsa strop progressions (sections II 4.3 to II 4.7), you can maintain the edge of that blade so that (baring physical damage) it should never need touch a whetstone/lapping film honing again. If you stick with this routine, you might even find that the blade’s edge will improve even more with time.

This is all done using the following steps:

1. At the completion of every shave wipe the blade clean with a piece of toilet paper to remove any moisture and soap residue left on the blade, being careful not to touch the blade’s edge.
2. Strop the blade on a clean cloth hanging strop or towel laid on the edge of a table to clean moisture and soap residue left on the blade’s bevels.
3. Perform a 0.1μm pasted hanging balsa strop only progression (see section II 4.6).
4. Wipe the blade clean with a piece of toilet paper to remove any diamond paste residue left on the blade, being careful not to touch the blade’s edge.
5. Oil the blade if necessary and put it away ready for its next clean leather stropping and shave.

Over a period of time, the pasted balsa strops will need to be re-lapped flat and new diamond paste applied. The required time varies from user to user dependent on how they strop and the grade of balsa they have. It is up to you to determine when you wish to refresh your balsa strops. A suggested starting point is:

• 0.5μm strop about every 1,000 to 2,000 laps.
• 0.25μm strop about every 2,000 to 3,000 laps.
• 0.1μm strop about every 4,000 to 5,000 laps.

When storing balsa strops there are two main things to consider. You need to prevent the possibility of cross-grit contamination and reduce the likelihood of the balsa wood warping. To meet these considerations, the balsa strops should be stored in a dry and reasonably temperature-stable environment. They should also be kept separated, each in their own dedicated air-tight container. Keeping each strop in its own labelled zip-lock plastic bag should be sufficient to prevent cross contamination. Storing the strops in say a bedroom cupboard or draw should provide the necessary suitable environment.

Of course there are many other suitable methods to store your balsa strops. It is your decision on which is the most convenient for you.

The most common reasons for failure in diamond pasted balsa stropping are:

• too much pressure
• not holding the balsa in hand
• too few laps
• too much paste
• not properly lapping the balsa wood flat

If your edge fails, correct your fault(s) and start again. With practice and patience, you WILL succeed! Most succeed within 2 or 3 tries.