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Substitutes for Platinum Paper

ccs, oz, water and grs

PLATINUM PAPER, SUBSTITUTES FOR Many attempts have been made to produce on bromide and other papers effects similar to those given by platinotype. A number of the platino-matt papers may be made to produce platinum-like prints, but the two can always be distinguished by applying a drop of a solution of mercuric chloride as used for intensifying. The solution bleaches the part of the bromide print to which it is applied, but has no effect upon a platinum print.

Special papers have been made for yielding prints resembling platinum, and of the home-made kinds, that prepared according to the formula worked out by Dr. Vollenbach, and published in the Deutsche Photo. Zeitung, is considered one of the best. It is said to yield rich deep platinum like blacks even from weak negatives. Paper is immersed for three or four minutes in : Gelatine . . . 22 grs. 5 g.

Citric acid . . 13 „ 3 Chrome alum (sol. r : 20) 220 mins. so ccs. Aluminium chloride (xo% sol.) . . 44 „ 10 „ Distilled water . io oz. 1,00o „ After immersion hang up to dry. It is sensi tised (in yellow light) with : A. Gelatine . . 2.2 grs. g.

Salicylic acid . •4 „ 1-10 „Distilled water . I oz. xoo ccs.

B. Green ammonia citrate of iron . 38 grs. 20 g.

Distilled water . I oz. roo ccs.

C. Silver nitrate . 55 grs. 12.5 g.

Distilled water . I oz. ioo ccs.

D. Uranium nitrate . 38 grs. 20 g.

Distilled water . 1 oz. mo ccs.

By using more of C, softer prints are produced ; more of B gives hard prints ; less of D gives browner tones ; and more of D gives blue-black tones. Por greyish-black resembling platino type, use r part of A and B and 2 parts of C and D. Mix in the order above given, or else a precipitate is formed and a muddy solu tion results. Pour the solution on the paper, pinned to a board, in a little pool and then distribute with a wad of cotton-wool ; finally dry quickly but evenly. Expose the same as with platinum paper until detail is faintly visible, and develop with Perrous sulphate . 188 grs. 43 g.

Acetic acid . . 67 mins. 14 ccs.

Distilled water . . io oz. x,000 „ When sufficiently developed, place the print in a r per cent. solution of nitric acid for three minutes and then fix in— Sodium hyposulphite 785 grs. 180 g.

Sodium sulphite (cryst.) iro „ Sulphuric acid . . 14 ruins. 3 ccs.

Water . . . to oz. r,000 „ The prints are apt to reduce slightly in the fixing bath.