THE BRITISH JOURNAL OF PHOTOGRAPHY. December 9, 1864, p.506
PICTURES ON OPAL GLASS. By HELSBY & Co., Liverpool.
IN our last number appeared an interesting and very practical communication from Mr. Williams on some modifications of the opal glass process, as practised successfully by Mr. Helsby, of Liverpool. We have now several of his specimens before us, all of which, without any exaggeration, are marvels of excellence. In tone and perfect definition they are even superior to those by Mr. Wenderoth, of Philadelphia, which were exhibited at the last meeting of the North London Photographic Association.
Instead of adopting Mr. Wenderoth's system of coating the plate with chlorised albumen, Mr. Helsby uses iodised collodion and exposes in the camera as described at page 484, in. preference to submitting the sensitised opal plate to direct contact with the negative.
Another peculiar feature in this new modification .is his method of protecting the picture by a piece of bevelled plate glass, cemented to the positive by means, of a drop or two of Canada balsam. In this way, by a slight pressure and the application of a gentle heat, the two surfaces are brought into optical contact, and all risk of the air acting injuriously on the collodion film which supports the photographic image is avoided. Collodion prints protected by such means, if they have been previously properly fixed and washed, ought, we think, to be considered absolutely permanent. That they are more durable than the most perfect photographic impressions on paper we have no doubt whatever. There is also a charming softness in the half-tones and transparency in the shadows which can only be seen in the finest ivory miniatures.
We would recommend to Mr. Helsby's attention an improvement in the mounting, which he, perhaps, may find useful viz., to surround the white opal and the bevelled edge of the protecting covering of plate glass with a band of gold leaf, or better still, gilded cord.
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