Blog

Posted on

Derek Cohen’s Stropping Compound Comparisons and Using a Strop

The following is a reposting of Derek Cohen’s “Stropping with green compound verses diamond paste”, which originally appeared on his website, In The Woodshop in January 2009. I thought it was quite well done (and not just because he likes my horsebutt strop) and since I often get questions about how to apply the compound, or what compound to use, he kindly granted permission for me to repost.  I collected some of my own thoughts on stropping here. Although he discusses a woodworkers chisel, the basic principals are the same for paring knives, spokeshave blades, etc.  He has a number of other tutorials about sharpening on his website. At the bottom of this post is an update after using the horsebutt strop for five years.

COMPARISON OF GREEN COMPOUND AND DIAMOND PASTES

I have been using a horsebutt strop with green buffing compound (.5 microns) for about two years. The strop is excellent with a hard and resilient surface, but I would recommend glueing it to hardwood for certain flatness. Used on their own they have a tendency to curl slightly, and this can lead to dubbing if one is not careful.

With the green compound I add a dribble of baby oil (which is just scented mineral oil). This turns the wax into a soft paste and allows the leather to soak it up. Used as a “crayon” alone it can become thick and collect on the surface (although it must be noted that the act of dragging a blade across this will remove – scrape away – the excess wax). Lee Valley also notes, “Frequent, light applications are better than less frequent, heavy applications”.

This is my strop with green compound applied.

For the purposes of comparison I set up another (unused) horse butt strop. There were two points of departure, but I did not think that these would interfere with the results. The first was that I used the rough (flesh) side of the strop since I wanted to save the smooth (hair) side for future use if this experiment failed. And second, I did not glue the strop to hardwood (but instead held it flat on ply) for the same reason.

To prepare the strop for the diamond paste I first moistened the surface with the baby oil.

The diamond paste was part of a batch I bought on eBay about 2 years ago (.5, 1, 10 and 40 microns). This is oil-based.

LV (Lee Valley) and TFWW (Tools for Working Wood) both sell water-based diamond paste. I generally use waterstones and, that this is oil-based, is not a concern since the two mediums are not used together.

So, dribble a little diamond paste onto the strop…

… and massage it in …

One observation about paste is that the excess sits on the surface of the strop in exactly the same way as the green paste. I would say that the criticism levied at the green rouge should equally apply to other pastes. Still, as I pointed out earlier, the excess is scraped off as one drags the blade across the leather.

I used 1/2″ and 3/4″ Blue Spruce chisels on Radiata Pine end grain. The chisels could cut but really needed work.

The chisel was stropped both back and bevel. Note that this involved drawing the blade towards oneself, with the sharp end trailing. Otherwise the blade will slice up the leather.

The result – the chisel was now several orders of magnitude sharper and had no difficulty taking fine shavings in this horrible wood:

Below is the result with the diamond paste – the chisel was now capable of excellent work:

Having gone back-and-forth between the two pastes, I concluded that they appeared to produce a cut that was almost identical. With he green compound, however, the chisel did appear to cut a tad more easily and leave a slightly smoother surface. When stropping it felt smooth, while the diamond paste felt “gritty” – but this may have been due to the rougher leather (still, it was not a “roughness” that I experienced).

Bottom line – I think that either system would work well. I shall continue using the diamond paste strop as I think that this should improve as the leather builds up more diamond within it.

USING A STROP

For those new to this, I have a few images of the stropping technique I use. Others may do this differently and, if so, I hope that you will post here.

Stropping the back of a chisel (or substitute a BD [Bevel Down] plane blade here):

Note that the blade is angled at 45 degrees, held flat, and pulled towards oneself (i.e. sharp end trailing). Do not push the blade bevel first – it will slice up the leather.

 

This chisel, like my BD blades, is hollow ground. Find the point of contact, then drag the blade back (as outline above).

Stropping a BU blade:

My BU [Bevel Up] blades typically have a 25 degree primary bevel and a high secondary/micro bevel (e.g. 50 degrees, to create a 62 degree included angle). The microbevel makes it difficult, if not impossible, to freehand strop accurately (that is, maintaining the secondary bevel angle). Consequently I only strop the back of the blade. This works well enough to give the blade a second lease on life.

 

Update: It is now 5 years on, and I continue to use the same strop with the green compound. It looks the same – the horse butt leather has lasted extremely well. What of the diamond paste? Well I did not like the feel – the subjective sense of grittiness remained. I learned that others experienced something similar.  The strop with green compound is less used since there is a sharpening bench alongside the work bench, and it is just as easy to use a 13000 Sigma ceramic waterstone, and in some cases this is better since there is no chance of dubbing the edge. I have continued to use the strop with green compound to “refresh” mortice chisels since these are honed with a rounded bevel.

I glued the undressed strop was to hardwood with the smooth (hair) side facing up. I have kept it that way, and it is used after honing blades to ensure that the wire edge on plane and chisel blades has been removed.

April 2014

Posted on

For Sale: Guttenberg Bible

Nuremberg, 1454-1455. 2 vols.  1,272pp.  This is the first book printed with moveable type in the Western World, only 48 copies known to exist, and only 21 are complete. This is the only one currently available for sale.

BACKGROUND. Detailed records of Gutenberg’s life and work are scant. He was born around 1400 in Mainz, where he trained as a gemstone cutter, goldsmith and door to door Bible salesman. In 1438, after moving to Strasbourg, Gutenberg entered into a partnership with Andreas Dritzehn, which enabled him to conduct experiments in printing with moveable metal type. It worked. He decided to release three collectable versions: the Gutenberg Bible, the Mazarin Bible, and the B-42.  Gutenberg is credited with being the father of modern printing. There is much speculation who the mother is.

PROVENANCE. Although completely undocumented,  this copy most certainly belonged to King Villhelmzholt of Strasbourg.  For many centuries this volume must have languished in a remote castle in the Alsace-Lorrane. Then a little bird asked someone to ask a friend to ask me to sell it for them.

COMPLMENTS

Inscription below Psalms XL:9 to XLII:8 which reads “COMPLIMENTS OF THE AUTHOR/ P.S. HAVE YOU SEEN MY NEW TOP TEN COMMANDMENTS”

DESCRIPTION. To date, this is the only know copy with the author’s signature “in the beginning”, an inscription from the author in Psalms XXX, containing a mysterious reference to “new top ten commandments”, and the original professionally unrestored dust jacket. Except for a few gaping holes at the foreedge, the dust jacket is is superb condition and has the only known photograph of the author. The lower margin of the text has intermittent light soil, some faint offsetting, a lingering odor of dog breath and tobacco smoke, and other trivial imperfections, but quite well preserved considering this grand old dame is over 500 years old!  The binding is broken, the corners have cracked, the flyleaves have flown, the clasps no longer clasp, the foreedge is fricasseed, bosses are broken, head caps are decapitated, and the spine suffers from scoliosis. Else fine.

This exquisite volume speaks eloquently of an antiquated age; of a time when skilled artists and craftsmen honored their Creator by creating churches, paintings, and books which combined spiritual contents with material beauty.  A very handsome and proper copy with a flawless, professionally unrestored dust jacket.  Without a doubt the centerpiece of any book collection.   $175,000,000.00 OBO. Buy now! Won’t last!  Shipping within continental US $4.14 USPS Media Mail.

Posted on

Three Methods of Measuring

1. DIRECT.  If at all possible, I prefer to measure directly, as this is often the most accurate, easiest and quickest. For example,  you are measuring a book for a box.  Put the book on a squared corner of binders board and mark the height and width directly on the board.

2. COMPARATIVE. This involves two steps. For example, you want to measure the width of a spine.  You could take a piece of paper and fold it around the spine, marking the width with a fold, pencil mark, or thumbnail indentation, then this can be used comparatively to transfer the measurement to a spine piece. An additional benefit of this method is repeatability. Dividers (technically called divider calipers) also measure comparatively, and they are often used in bookbinding to space sewing holes or holes. A jig (aka. template or guide) would also fall into this category, since they are a separate materials set at a desired measurement. Examples of this include using the width of a ruler to trim turn-ins after the boards are adhered to the covering material, or a corner jig to cut a precise 45 degree corner.  Also, the inner and outer gauges on a board shear (which can be set comparatively or numerically) are technically fixtures, not jigs, since the hold the workpiece and don’t guide a cutting tool.

3. NUMERIC. This is often what people think of as measuring. It involves taking a comparative measure, then transferring it to numbers, then transferring the numbers back to a comparative length. This gives you three chances to make a mistake. But for large projects, or ones with multiple workers, this is often the best method. Vernier, Dial or Digital Calipers can be used comparativly or numerically, in fact if they have Statistical Process Control (SPC) they allow a third party to track and record the accuracy, possibly placing them in a different category altogether. Digital box measuring machines, such as the KASEMAKE Book Measure, also convert physical dimensions to numbers.

There is not one best way of measuring for every circumstance, but it is good to evaluate options depending on the task.