IMPROVEMENTS IN GLAZES FOR POTTERY OR OTHER SIMILAR MATERIALS
Year: 1853

page_text: LETTERS PATENT to Thomas Lightfoot, of Accrington, in the
County of Lancaster, for the Invention of "IMPROVEMENTS IN
GLAZES FOR POTTERY OR OTHER SIMILAR MATERIALS."
Sealed the 28th March 1853, and dated the 31st January 1853.
PROVISIONAL SPECIFICATION left by the said Thomas Lightfoot
at the Office of the Commissioners of Patents, with his Petition,
on the 31st January 1853.
I; THOMAS LIGHTFOOT, of Accrington, in the County of Lancaster,.
do hereby declare the nature of the said Invention for "IMPROVEMENTS
IN GLAZES FOR POTTERY OR OTHER SIMILAR MATERIALS" to be as follows:-
I' propose to use, as part of the composition for glazes, pottery,
&c. a silicate of an alkali in such proportions as to be soluble in
water, and I mix and grind it with the substances ordinarily en-
tering into compositions used for glazing, dispensing entirely or in
part with borax.
I desire it to be distinctly understood that this is merely an
outline description of my Invention, which I will more fully
explain in my Complete Specification.

page_text: SPECIFICATION in pursuance of the conditions of the Letters
Patent, filed by the said Thomas Lightfoot in the Great Seal
Patent Office on the 30th July 1853.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I,
THOMAS LIGHTFOOT, of Accrington, in the County of Lancaster,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent, bearing date the Thirty-first day of January,
in the year of our Lord One thousand eight hundred and fifty-three,
in the sixteenth year of Her reign, did, for Herself, Her heirs
and successors, give and grant unto me, the said Thomas Lightfoot,
Her especial licence that I, the said Thomas Lightfoot, my executors,
administrators, and assigns, or such others as I, the said Thomas
Lightfoot, my executors, administrators, or assigns, should at any
time agree with, and no others, from time to time and at all times
thereafter during the term therein expressed, should and lawfully
might make, use, exercise, and vend, within the United Kingdom of
Great Britain and Ireland, the Channel Islands, and Isle of Man, my
Invention of "IMPROVEMENTS IN GLAZES FOR POTTERY OR OTHER SIMILAR
MATERIALS" upon the condition (ainongst others) that I, the said
Thomas Lightfoot, should particularly describe and ascertain the
my said Invention, and in what manner the same was to be
performed, by an instrument in writing under my hand and seal,
and cause the same to be filed in the Great Seal Patent Office
within six calendar months next and immediately after the date of
the said Letters Patent.
nature of
NOW KNOW YE, that I, the said Thomas Lightfoot, do hereby
declare the nature of my said Invention, and in what manner the
same is to be performed, to be particularly described and ascertained
in and by the following statement that is to say:
My Invention consists in the use of compounds of silicic acid,
and an alkaline base or bases, in the formation of glazes on pottery,
such silicated alkali being in part or wholly used in place of borax.
The silicates I prefer are such as are soluble in boiling water. And

page_text: in order that my Invention may be clearly understood, I will
proceed to give the method in detail of producing a glaze on pottery
with the aid of a silicated alkali. I mix together ninety-two pounds
of clean dry sand, seventy-fivé pounds of crystallized carbonate of
soda, and forty-four pounds of crystallized carbonate of potash, or
its equivalent in pearl ash, and put the mixture in a reverberatory
furnace or a crucible heated in any convenient manner.
After
drawing off the water; I raise the heat till fusion takes place, and
continue the heat until the compound appears perfectly glassy,
when a sample is drawn. I then withdraw it, and allow it to cool.
It is then broken up and ground to powder. To one hundred
pounds of this I add forty pounds of Spanish white, twenty-four
pounds of china clay, and one and a half ounce of oxide of cobalt.
The mixture is then put in a crucible or furnace, and fused four or
five hours, when it is withdrawn, and cooled. This substance I
call the frit. I then take ninety pounds of this frit, seventy-five
pounds of felspar, and forty-four pounds of white lead, and grind
all together with water to an impalpable powder, which constitute
the glaze. This is reduced to a creainy consistence with water,
the biscuit ware dipped in, and when coated uniformly with the
compound, fired in the usual, furnace, but with a somewhat increased
heat. In cases where a lower heat of firing is necessary, instead
of one hundred pounds of silicated alkali in the aforesaid frit
mixture, I take seventy-five pounds only, and twenty-five pounds
of borax, which I add to the other ingredient, and proceed as before.
In some cases I introduce the silicated alkali in a dissolved state.
I boil the silicated alkali in water till dissolved, and evaporate the
solution till it contains five pounds of silicate per gallon. This
solution is used in place of water in grinding the glaze, but in this
case a less quantity of silicated alkali is used in making the frit;
for instance, for every gallon of solution containing five pounds of
silicated alkali used in grinding the glaze, I put five pounds less of
silicate in the frit. The glaze thus made contains liquid silicated
alkali in addition to the other constituents, and this is found useful
in promoting uniformity in the fired glaze.

page_text: Having thus explained the nature and particulars of my said Inven-
tion, and the manner of carrying the same into practical operation,
I desire it to be distinctly understood that, in thus giving the com-
position of a glaze, I do, not confine myself to the exact proportions
herein given, so long as the peculiar nature of my said Invention
be retained, which is the composing a glaze for pottery, or other
materials, in which silicated alkali, or, solution of silicated-alkali,
enters as a constituent or component part, and whereby. the use
borax is altogether, or in part, dispensed with.
of
In witness whereof, I, the said Thomas Lightfoot, have hereunto
set my hand and seal, this Twenty-eighth day of July, One
thousand eight hundred and fifty-three.
THOMAS LIGHTFOOT. (L.S.)
Signed, sealed, and delivered by the
within named Thomas Lightfoot
in the presence of
CHA. WALL, Solicitor Accrington.
GEO. ELLIS; his Clerk.