View source for Glazing jack

{{Short description|Machine used for polishing leather}}
{{Orphan|date=September 2018}}
[[File:Glazing jack diagram 2.png|thumb|right|upright=1.0|alt=Patent diagram of a glazing jack|Diagram of a typical glazing jack, from a 1901 patent]]

A '''glazing jack''' or '''glazing machine''' is a type of machine used for [[polishing]] [[leather]]. The machine consists of a solid [[glass]] cylinder, typically around {{convert|2|inch|cm|spell=in|0}} in diameter and {{convert|6|inch|cm|spell=in|0}} in length, mounted to the end of a rotating or [[reciprocating motion|reciprocating]] arm. The arm repeatedly and rapidly draws the glass across the surface of the leather, with significant downward pressure, as the operator moves the leather underneath the arm.<ref name="jarnagin">{{Cite web
 | title = Jacked Leather
 | work = Leather Finishing Methods
 | publisher = C & D Jarnagin Co., Inc.
 | url = http://www.jarnaginco.com/jacked%20leather.htm
 | access-date = 2009-12-06 }}
</ref><ref name="sci">{{Cite episode
 | title = Racing shells, stainless steel sinks, leather, and pedal steel guitars 
 | series = How It's Made
 | series-link = How It's Made
 | url = http://science.discovery.com/fansites/howitsmade/howitsmade.html
 | network = [[Science Channel]]
 | season = 9 
 | number = 7 }}</ref>

The repeated stroking of the leather smooths and compresses the surface and raises various color tones. Heat generated by [[friction]] during the glazing process can darken and harden the [[aniline]] finish of the leather, and can raise oils in the leather to the surface. Because no pigment is used, the [[porosity|porous]] structure of the leather remains visible, providing a depth to its appearance. The operator of the glazing jack can control the surface finish by varying the pressure of the tool and the number of strokes applied. Similarly to glazing, a [[copper]] or glass tool can be drawn across the leather by hand to create "sleeked" and "glassed" finishes, respectively.

Because jacking leather is a time-consuming and labor-intensive process, it is often reserved for more expensive or exotic leathers, such as [[reptile]] leathers.


==See also==
*[[Surface finishing]]

==References==
{{Reflist}}

{{Leather}}

[[Category:Leather crafting]]
[[Category:Machines]]


{{Tool-stub}}