Post by David "Doc" LeifheitPost by RicodJourYou are either using words loosely and creating confusion, or you
yourself are confused. Enamel usually refers to fused glass
(vitreous), or a paint with a similar sheen. The first is an exact
description, the second a rather vague one. Everyday cans are not
lined with fused glass in this day and age, and I tend to doubt that
"paint" (another loose term) was ever used, so I do not know what
exactly the enamel was on the packages you worked with back when.
The term used on the websites is a laquer finish.
Post by RicodJourCans are lined with plastic. Check out some of Georgia Pacific's
http://www.gp.com/Chemical/indres_coat.asp?RC=1&BS=187|Coil/Food%
20Can%20Coatings|186|Coil/Food%20Can%20Coatings&DC=1|Industrial%20Resins
Post by RicodJourNotice the words acrylic, polyester, vinyl. epoxy and phenolic. These
are plastics as they all undergo polymerization. That is the basic
definition of a plastic. Some of them are thermoset and others are
thermoplastic, but they are all plastics, and that is what lines every
can you buy from the store.
Notice that when you read the data sheets, the items listed are approved
for use as coatings on paper containers and as the gasket on cans. Not
the lining on the can, just the gasket area where the lid is seamed onto
the can.
The pallets and boxes were labelled "enamel" and we had to make certain
that the lids and cans were of the same coating. I also had to work
with the quality control department to make sure that the stamped codes
on the cans were not cutting through or cracking the coating on the
inside of the lids.
http://www.steeluniversity.org/content/html/eng/default.asp?catid=235
&pag
eid=2081272441
Lacquering
This is the application of an organic coating to create a barrier
between the steel and its contents (filling) and the external
environment (atmosphere). The flexibility of the exterior coating
depends on the type of can or component being manufactured. The interior
coating depends on the kind of product and processing environment. This
will influence the thickness of the coating too. Tinplate food and
beverage cans are internally lacquered to prevent chemical action
between the filling and the can wall and to prevent metal dissolution
into the filling. For dry contents (interior) and the exterior of cans,
tinplate provides sufficient protection and does not need lacquering.
For white fruits and sometimes tomato based fillings the can walls are
unlacquered to allow low level tin dissolution which preserves the
original color of the filling.
http://www.cancentral.com/hist_timeline.cfm
1921
Zinc oxide and other zinc compounds in an enamel lining were found to
prevent discoloration of canned corn by "corn black" or zinc sulphide.
To quote Ronald Reagan, "There you go again!" Loose verbiage.
Please note "other polymers" and acrylic. The lining of cans is
plastic. Just deal with it.