I tried to send this out on Tuesday - so because it seems that it didn't go
through, here it is again:

The date of 1805 that is usually used as the beginning date for Albany slip
is a cautious estimate.  As Tim Scarlet noted, Greer says that Albany slip
was developed during the first quarter of the 19th century and no one has
yet - to my knowledge - done more research about Paul Cushman and his use
of this clay.  (If anyone has, let us know!)  If you can identify the slip
as Albany Type, 1805 is a reasonable, conservative, beginning date.  Albany
Type is usually defined as having a medium brown to dark brown verging on
black color, depending on firing conditions, the source of the slip, and
any additions.  However, as Bill Liebknecht noted, potters, including those
mentioned by Bill and the Crolius/Remmey potters in NYC, used interior
brown slips from at least the mid-18th century on.  These slips, or at
least those that I have seen, are lighter colored and thinner than the
Albany Types; it's not hard to distinguish visually between the earlier
slips and Albany Type but you have to have looked at a fair amount of
sherds and vessels.  Go to antique stores and look at the large,
straight-sided 19th and early 20th century jars that they often have for
sale.  A lot of these will have Albany-Type slip and you can get a good
feel for what it looks like.  The use of Albany Type slip was part of the
early 19th century techniques that stoneware potters used to adapt to
changing market conditions and, even though it grew out of the earlier use
of other clays for interior slips, it's an important marker.  Don't throw
out the 1805 date just yet.

Meta Janowitz