Jakob,



      I do not know of any semi-automatic bottle blowing machines where the

finish was done by hand.  All of the semi-automatic and fully automatic

machines that made bottles have a ring mold that creates the finish and

serves as the device for moving the hot parison from the blank mold to the

blow mold.  The parison mold contained the amount of glass needed to blow

the bottle and distributes that glass so that it can be evenly blown in the

blow mold.  Mold lines from the blank mold are rarely in complete alignment

with the blow mold and this results in what has been called “ghost mold”

lines.  It might be better to call them parison mold lines.  There are a

couple of things that cause the parison mold lines to be misaligned with

the blow mold lines.  One is when the parison is moved from the blank mold

to the blow mold, it is still quite liquid and could be swayed by the

process of moving it.  The second is that air jets used to cool molds could

cool one side of the parison which would cause that side of the parison to

expand at a slower rate than the other side thus creating a distortion that

would result in the off-center parison mold line we so often see in the

base of machine-made bottles.  The Owens scar is one of the better-known

parison mold lines.  It is almost always on the edge of an off-center

circle from the blow mold lines.  However, in some cases, when the knife

that cuts the glass off during the gathering process is working well and

the glass is just the right temperature, the base may not have an Owens

scar.  I have cataloged two identical bottles with the same mold numbers

and shape where one has a visible Owens scar and the other did not.  Thus,

we can be sure that a bottle was made on an Owens machine if the scar can

be seen.  It is possible that in rare cases the parison mold could be in

alignment with the blow mold and in such cases, it would be very difficult

to see any parison mold lines.



      For a long time archaeologists and collectors have used the mold line

over the rim to identify bottles as being machine-made.  These lines can be

burned away when the bottles are fire polished, but that mainly was done

for beverage bottles.  If the mold lines stop below the rim it could still

be machine-made.  I have not been able to pin down the beginning date for

fire-polished finishes.  If there are drag lines from a finishing took,

then I would say that the bottle was mouth-blown.



George L. Miller

URS Corporation

437 High Street

Burlington, New Jersey 08016

                                                                              

 This e-mail and any attachments are confidential. If you receive this        

 message in error or are not the intended recipient, you should not retain,   

 distribute, disclose or use any of this information and you should destroy   

 the e-mail and any attachments or copies.