The daily telegram. [volume] (Clarksburg, W. Va.) 1901-1926, 1915-02-08
|NAYS10|P|TH
INSPECTION
OFPORCELA|N.
Method Of Purifying elayeFound
in This Country is
Discovered.

ulSG0veFeu.
WASHINGTON. d. C.; Feb. s.
In recent months the bureau of stan
dards, OF the department Of COM
inerce. hac been conducting expert-
ments for the purpose of detern,ln-
ing the utility of American materials
for. the manufacture OF certain ar
ticles heretofore imported almost en-
tirely from Europe.
Up to the present time. practically
all the porcelain crucibles and dish
cs used in chemical laboratories
throughout the country have been
imported from Germany. Two years
ago the clay products section OF the
bureau undertook TO ascertain
whether or not American materials
we're suitable for the manufacture of
this porcelain. The investigation de-
yeloped that clays existed in thla
country from which such wares could
be made and which were equal 10
the foreign product so far as their
resistance TO temperature changes is
concerned, auuality absolutely essen
tial in this ware. but owing to impur-
ities in the clay the ware was defec-
tive in color. Recently, the clay
products section has developed u
method OF purifying the clay, which
makes possible the manufacture Of
ware of good color, detail import
ant not only in this particular ware
but in all white wares. One concern
has taken up the manufacture of
chemical porcelain, and while the
process is yet somewhat in the exper.
mental stage, 1t is probable that in
q short time all varieties Of such
ware will be made in this country.
Leadless Glages Used.
In the manufacture of chemical
porcelain and similar products. lead
less glazes are the only ones that can
be used. For this reason and on ac-
count of the poisonous nature Of the
lead compounds used in making tho
usual type Of white ware glaze, tho
bureau has been conducting an ex-
detrimental study in the field Of le.d-
less glazes.
The use of lead compounds. has
given rise to widespread agitation
concerning its deleterious infiuencs
upon the heath of workmen under
conditions permitting careless oper-
alton and neglect of ordinary sanitary
precautions. "A study Of American
white ware potteries shows, however,
that such conditions do not prevail
and that in reality the i'll effects due
to plumbism are very slight in ex-
tent. It can not be denied that there
is a potential danger, but white ware
and china glazes. made with lesd
compounds, may be used under prop
|er conditions and by observing suit
able precautions without any danger
to the health of the operatives. On
the other hand, wherever ls d1ess
glazes can be developed and used.
such precautions, which in themsel-
yes increase the cost Of manufacture,
do not have to be taken and every
element of risk is thus eliminated to
the mutual advantage of both en-
lployer and employee. The question,
therefore, of lead glazes VS.. leadless
glazcs for china or white ware be.
comes one OF purely technical and
practical interest involving the fac.
tors of working properties, quality
of finished product and cost.
The leadlcss glaZes are not an
exact substitute for lead glazes. Both
have their peculiarities. However, il
is not at all unlikely that the produc,
1 ton Of American porcelain in the
near future will lead toward the pro
duction OF leadless glazes in natural
way, as with a higher biscuiting fire
that is, the IRE used in the first bak,
ling of the ware before any glaze i:
applied, It is not at all improbable
that the glost or glaze firing. a sec
4 nd or later baking TO harden tn,
glaze, may be raised also. In the pro
duction of such articles as chemic;,
porcelain. however. tael common
\ American practice must be reversed
/ Instead Of high biscuit and Low
lglost fire, a low biscuit and high gios
heat must be used.
II Wide Range.
1t was found that TIE best lead
less glaze worked out in the bureau
laboratory could be applied upon th,
4 biscuited ware as well as the usua
lead glaze, but in firing the temper
iIature range OF the leadless glaze va
found 10 he narrower than that o
the lead glaze. However, the rang
lis sufficiently wide to take care Q
Variations met with in very uniform
firing, condition, though. which I
/ the exception rather than the rule
! Leadless glases do not seem to hav
la detrimental effect on, the. under
glaze colors, with the exception .
pink With certain colors the
brought about better brilltancy thai
the lead glazes. They are white
than the lead but, in the white, some
what less brilliant.
There is no question but that lead
less glaze could be used for u va1
!. iety of products. especially for al
chitectural ezra Gotta, tile enamelc
brick, etc. With reference to po.
terry, the leadless glazes do not es
actly replncs the present lead boraci
iacid glazes. There is nothing to pre-
went the, technical application q