Originally Posted by Steven Cash
Today's question relates to stitching.
Is there an optimum SPI for both form and function? I'm sure there is a different answer for every kind of leather and between the stitching of uppers and the actual welting but I would be interested in the actual workings and any shortcomings of higher SPI work.
I know certain maker's work has been regarded as being "coarse" in the past for the relatively low SPI on their uppers but is this purely an aesthetic preference or is there an actual benefit to a higher SPI?
Thanks in advance.
This is a hard question to answer...there is
a functionality in tighter work...up to a point. Inseaming done much below 3spi for instance is not as water resistant and much more likely to gape. Such coarse work doesn't "show" well and that in and of itself is an indication that the connection itself is loose. As such, and worse, it will admit dirt and that dirt...that grit...will abrade and weaken the seam. Such coarse work also puts a greater stress on the materials it is supposed to be holding together.
I try to inseam at about 4spi, sometimes flexing to a tighter frequency and sometime to a looser (3spi) in areas where tighter stitches are difficult to produce...such as around narrow toes.
Much of the same considerations apply to upper work. But you are correct in thinking that the temper and substance of the leather has much to do with it. I generally sew at 15 -18 spi on uppers but if I am making a rugged boot, I will often "open up" a little simply because it looks more balanced on heavy leathers---I will also choose a heavier thread in such circumstances. But again, if opening up is done simply for appearances sake, it risks weakening the connections and jeopardizing the potential lifespan of the shoe.
At a certain point, especially with machine work the frequency of the stitching as well as the substance of the needle can combine to "postage stamp" the leather--perforate it so relentlessly that the leather is irreparably damaged and weakened. Much beyond 20spi except on dense, strong leathers such as kangaroo is starting to be counterproductive, IMO. (Although I have seen really, really fine machine work on some vintage shoes).
Where is the "sweet spot?" It depends on the leather and undoubtedly on the eventual use. At one point in time shoemakers hand stitched both the uppers and the welt at frequencies in excess of 50 stitches per inch (up to 64 spi has been recorded)...and all by eye. No living shoemaker that I know of has the skills to do that anymore. But the leather is markedly different, as well.
June Swann, long time keeper / curator of the Shoe Collection at the Northampton Shoe Museum, and maybe the
foremost shoe historian in the world, has pointed out that with growth hormones and feed supplements as well as the genetic and financial emphasis of raising beef primarily for meat rather than the hides, the raw hides themselves are not of the quality or temper of what was being produced 150 years ago. So high frequency work is near-as-nevermind impossible...even if we had someone who knew how to do it.
But most or all of that work was for show--for World's Fairs and International Exhibitions and not intended for actual use. 20-30spi by hand and by eye is another matter. Some women's work was done at those kinds of frequencies as a regular thing.
All that said, much of it is aesthetic preferences--the eye of the creator, so to speak. Coarse is often seen as "bold" but bold is all too often objectively
And the real problem with "fine"...beyond the time and skill it takes to do it, of course...is that it tends to recede into the background. As all things "finessed and elegant" do. It is not "in your face." Nor ostentatious....and ostentatious ("esp. at these prices") is what all too many people seem to prefer these days.
You have to look closely...and be somewhat knowledgeable...to really appreciate high frequency, high quality work. And that's just too much trouble.
--Edited by DWFII - 9/20/16 at 6:42am