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When complete solution is effected the material is ready to use. If it is 
to be employed as a spray or for impregnation it should be greatly thinned 
with acetone; if as a cement, it may be allowed to evaporate for a few 
minutes in a shallow dish and its viscosity will increase rapidly. 
Amyl acetate may be used instead of, or in combination with, acetone, 
but as it is somewhat poisonous and no advantage attends its use, it is 
probably better to stick to the acetone. Again, cellulose acetate may be 
used instead of celluloid, but here, too, there is no advantage, except that 
the cellulose acetate is in the form of a powder and dissolves more rapidly 
in acetone, thus saving the time expended in cutting up the sheet celluloid. 
It is, however, not quite so satisfactory in actual practice. 
Some trouble may be experienced in that the celluloid in acetone 
solution sometimes turns white after the acetone has evaporated. This 
is usually an indication of the presence of water, either in the acetone or on 
the specimen, perhaps in very small quantities. Microscopical examination 
of the white film formed shows it to be filled with minute bubbles. The 
difficulty may be overcome by using double-distilled acetone and making 
sure that the specimen is thoroughly dry before treating it. The white 
deposit, should it appear, may easily and quickly be removed by means of 
a little acetone on a tuft of cotton wool or a brush. 
In using the celluloid in acetone solution as a spray an ordinary 
atomizer of the nose-and-throat type will be found useful. After use it 
must be cleaned with pure acetone or the solution will harden in the atom- 
izer and freeing the passages will prove a long and tiresome process. The 
same rule applies to brushes, which should be rinsed very thoroughly in 
acetone after being used in the solution. It is well to keep a small, well- 
corked bottle of acetone for this purpose, and when it shows signs of thick- 
ening it can be added to the stock solution. 
There are, of course, many other materials and processes which must 
be used in dealing with various specimens. These will be discussed in 
detail under the appropriate headings. 
REPAIRING 
Though most repairing involves little more than the use of cements 
and glues, the addition of braces is sometimes necessary. These may be 
made of any suitable material and should be so placed that they will be 
invisible when the specimen is exhibited. The fact that such material has 
been added to the specimen should always be noted in the catalogue. 
In replacing old adhesives with new, the original glue or cement 
should always be softened with an appropriate solvent before any attempt 
is made to remove it. Dry adhesives are likely to take part of the specimen 
itself with them when they are chipped or scraped off. Surfaces to be 
cemented together should be perfectly dry and clean and the adhesive 
spread in a thin coat on both surfaces. Once the pieces have been placed 
in the correct positions they should be left clamped, tied, or braced to- 
gether until perfectly set. Pulling them apart and replacing them while the 
cement is still wet will almost inevitably result in a poor job. In repairing 
brittle materials such as pottery, do not fit the edges together until you are 
ready to cement them, as the friction will be almost certain to chip off small 
fragments which are then lost and a perfect joint can no longer be secured. 
