Improvements in Treating Natural Alabaster for enabling it to take a Fine Polish and to Resist Atmospheric Influences.
Year: 1898

page_text: Date of Application, 10th Jan., 1898-Accepted, 26th Mar., 1898
Improvements in Treating Natural Alabaster for enabling it to
take a Fine Polish and to Resist Atmospheric Influences.
I, HENRY FRANCIS LAMOCK, of Aspelt, in the Grand Duchy of Luxemburg, Manu-
facturer, do hereby declare the nature of this invention and in what manner the
same is to be performed, to be particularly described and ascertained in and by the
following statement :—
Alabaster consists of sulphuric acid and lime and contains sometimes foreign dis-
colouring matters, for naturally it is white, but in any case it is translucent to some
extent. It is soft and fine grained and easy to work. If on the one hand the little
hardness which the alabaster offers to the workmans tool is an advantage, it
becomes in the finished article a defect because it is too soft to retain a fine polish
and because the alabaster easily absorbs humidity from the air and cannot in that
condition resist prolonged cold.
It is therefore the object of this invention to treat alabaster pieces and articles so
as to give them a certain hardness for enabling the alabaster to take a polish, to
give it a greater hardness so that it can be employed under the same conditions as
marble, and to fill its pores so as to resist the humidity of the air which in frosty
weather would cause it to crack.
According to this invention the alabaster pieces as they come from the saw or
alabaster articles when finished in form but by preference not yet polished and
while containing moisture in the pores of the surface are placed in a suitable drying
apparatus. This may be of the form shewn in the vertical section Fig. 1 and plan
section Fig. 2. It is a chamber heated by lower pipe coils with live steam, or with
exhaust steam from the engine which works the saws. The dry heat produced in
the chamber should be at least 80° C.. The various articles or pieces of alabaster
are placed so as not to touch each other and so as to present the greatest possible
surface to the drying action, and for this purpose I place them on trellis shelves.
The drying chamber must have sufficient means for ventilation for easily carrying
off the humid air, without carrying off needless heat.
The pieces after leaving the drier are placed in an openworked tray or cradle such
for instance as shewn in Fig. 3 made by preference of iron rods so as to present few
points of contact with the pieces. The cradle is provided with handles for easy
handling, which is necessary in order to obtain a uniform treatment of the pieces.
The cradle with the pieces on is then plunged into a vat containing the proper
liquid. This vat may be as shewn in Fig. 4 and contains a solution of fluosilicate
of magnesium at 40° Baumé. This solution should be kept cold. The vat should
be large enough for easily plunging the cradle into it. The alabaster greedily
absorbs some of this solution. The cradle is taken out after a short immersion, and
when the liquid on the surface of the alabaster pieces has been absorbed it is plunged
into the bath again. This should be repeated until no more liquid is absorbed that
is to say till the alabaster surfaces remain moist.
In cases where the articles have had opportunity to dry in the air, it is expedient
to put them in water in order to absorb as much as possible of it before putting
them in the drier. At a temperature of 80° C. the water evaporates quickly enough

page_text: but the vapours do not acquire a pressure to hurt the solidity of the articles, and
the pores of the alabaster remain filled with watery vapour at this temperature
while the pieces themselves do not cool down.
When the pieces have been treated as above described they are quite susceptible
of taking a fine polish rendering them absolutely similar to marble and having a
hardness and solidity not inferior thereto.
The operation described may be repeated even several times, but it is then
advisable to put the pieces in the drier while still saturated with the solution; the
water of the latter then acts like the pure water in the first case.
- Having now particularly described and ascertained the nature of my said in-
vention and in what manner the same is to be performed, I declare that what I
claim is :-
1. The employment of a fluosilicate of magnesium solution for treating alabaster
pieces or articles in order to render the surface hard and non absorbent of moisture,
substantially as set forth.
:
1
2. The process for rendering the surface of alabaster pieces or articles hard and
non absorbent of moisture consisting in placing them in a drying stove and then
immersing them in a cold solution of fluosilicate of magnesium substantially as set
forth.
3. The process for rendering the surface of alabaster pieces or articles hard and
non hygroscopic consisting in placing them in a drying stove, and then immersing
them in a cold. solution of fluosilicate of magnesium and repeating such drying and
immersing operations substantially as set forth.
4. The employment of the apparatus shewn and described as and for the purposes
set forth.
Da L 1
L
1000

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