RU2229153C2 - Process restoring daguerreotypes - Google Patents

Abstract

FIELD: restoration of photographic plates-daguerreotypes, silver or silver-plated copper plates. SUBSTANCE: described process of restoration of daguerreotypes includes mechanical cleaning of inverse side and faces of plate to undamaged body of plate, removal of products of mechanical machining followed by intermediate drying in air, degreasing of plate, intermediate drying at enhanced temperature with subsequent treatment in cleansing solution (containing, mass parts: thiocarbamide 60.0-80.0, 85% orthophosphoric acid 60.0-90.0, nonionogenic wetting agent photoflo 1.0-5.0; distilled water up to 1000.0), rinsing in water, then in acetone, drying at enhanced temperature and plate framing. EFFECT: restored quality of visual recognition of photographic image and of qualitative index of surface of daguerreotypes. 10 cl

Description

The invention relates to the field of photographic materials, in particular to a method for the restoration of photographic daguerreotype plates, silver or silver-plated copper plates, the photographic images of which darken when exposed to the environment, sometimes becoming completely indistinguishable.

A known method of enhancing weak diaimages (SU 138815, 1961), using copying on positive-copy layers. However, this method does not allow to restore the original itself, and copies lose in resolution and other indicators of the quality of visual perception. There is also a method of enhancing silver images, reducing the veil and obtaining high optical densities SU 1684773, 1991. However, the known method does not allow for high-quality restoration of daguerreotypes.

The closest analogue of the proposed method for restoration of daguerreotypes is a method that includes image processing with a cleaning solution, washing with water and final drying (Museum News, “Eugene Ostroff, Conserving and Restoring Photographic Collection”, 1974, v.53, N3-4, p. 42-45 , part 3).

The disadvantage of this method is the insufficient quality of the restored photo image.

The technical problem solved by the proposed method is to restore high-quality visual perception of photo images and qualitative indicators of the surface of daguerreotypes. According to the invention, the method of restoration of daguerreotypes includes processing the image with a cleaning solution, washing with water and final drying, and before processing the image with a cleaning solution, the back side and the ends of the plate are mechanically cleaned to the undamaged body of the plate, mechanical cleaning products are removed, intermediate drying is carried out in air, the plate is degreased, carry out intermediate drying at elevated temperature, followed by treatment with a cleaning solution containing leduyuschie components, wt. including: thiourea 60-80, 85% phosphoric acid 60-90, nonionic wetting agent photoflo 1-5, distilled water up to 1000, washing with water, then with acetone, drying at elevated temperature and wrapping the plate under glass.

It is advisable to carry out mechanical cleaning with a polishing paste with a cotton swab.

It is preferable to remove the cleaning products by rubbing with a cotton swab with alcohol, and degreasing by immersion in chemically pure acetone for 1-2 minutes.

Advantageously, after exposure to the cleaning solution, dimethylformamide with an elevated temperature is immersed in the cleaning enhancing cleaning agent, and then the plate is again immersed in the specified cleaning solution for 1-2 minutes.

It is also advantageous that a selective brushing application of a brightening solution — a 2% aqueous solution of sodium borohydride — is carried out with a synthetic brush, after which the plate is washed successively with water and acetone.

Preferably, the plate is additionally treated with an oxidizing solution - an 8% hydrogen peroxide solution, acidified with phosphoric acid to pH 2 for 5-10 minutes, followed by washing with water and then with acetone.

It is preferable to chemically apply a protective layer of gold to the image by immersing the plate in an aqueous solution of the thiosulfate complex of monovalent gold and keeping it at elevated temperature until a weak golden tone appears.

Preferably, the washing is carried out with distilled water.

The proposed method (restoration of the image on daguerreotype plates is carried out in several stages as follows.

Example 1

For the restoration of daguerreotypes, the authors first developed a comprehensive technique (method), consisting of the following stages:

1. Optical microscopic diagnostics of the state of conservation and types of image damage. The state of conservation is recorded by photographing both the entire image and individual areas with damage (digital or optical microscopes). In cases of severe loss of image, research and photographing in infrared rays are used.

2. Cleaning the turn and ends of the plate (in the case of a copper substrate) to fresh copper with any polishing paste for copper products, for example, Centralin paste (Germany). The paste is suitable for cleaning and polishing products from all metals. It includes surfactants, aliphatic hydrocarbons, polishing agents, silicone, etc. When cleaning, the daguerreotype is held by the ends in the left hand, and carefully so that the cleaning paste does not get onto the image, the turnover and end parts are cleaned with a cotton swab. Work is done in rubber gloves. After polishing with paste, the copper parts of the plate are thoroughly wiped with a swab with hydrolytic ethyl alcohol 95% and dried in air. Stage 2 is necessary for two reasons: 1 - so that the corrosion products of copper do not transfer to the image during further chemical cleaning of the image in the cleaning solution, 2 - after the plate is edged in a closed volume (under the glass), copper is oxidized faster than silver during storage; therefore, it must be cleaned and thereby activate.

3. Degreasing in acetone brand H.H. For this, the daguerreotype plate is completely immersed in an enameled cuvette with the required amount of acetone for 1-2 minutes, removed and dried with a hot hairdryer at a temperature of 60-70 ° C.

4. The daguerreotype plate is completely immersed at room temperature in an enameled cuvette with the following solution, parts by weight:

Distilled water 500

Thiourea 60

Phosphoric Acid 85% 60

Photoflo ^x 1 nonionic wetting agent

the solution is added to 1000 parts by weight H ₂ O

^x Manufactured by Kodak and is a non-ionic wetting agent based on polyethylene glycol.

After placing the plate in the specified solution, the image is quickly cleaned, details are clarified, and a specular gloss appears. If this does not happen completely within 3-5 minutes (brown spots remain or darkening does not go away at the edges of the plate), proceed to the next stage.

In an enameled cuvette with dimethylformamide heated to 60-80 ° C, the daguerreotype plate is completely immersed for 1-2 minutes, after which it is transferred to a cleaning solution (stage 4 is repeated).

6. * In cases of deep pitting corrosion, you can additionally enter the stage of processing the plate with a 2% solution of sodium borohydride. In this case, the solution is applied to the necessary areas with a synthetic brush and left until the image is clarified, after which it is thoroughly washed with water and acetone.

7. * If necessary, and according to the results of spectral analysis (IR-Fourier spectroscopy) include the following processing step: the plate is placed in an 8% aqueous solution of hydrogen peroxide, acidified with phosphoric acid to pH 2 for 5-10 minutes, and then washed thoroughly with water and acetone.

8. * In case of abrasive damage to the image and in some other cases (the issue is solved individually for each image), an additional stage is possible that protects the image from further corrosion. It consists in applying chemically a thin protective layer of gold. For this, the plate is immersed in an aqueous solution of the thiosulfate complex of monovalent gold heated to 60-70 ° C and kept in it until a very weak golden tone appears. The solution can be prepared independently according to the following recipe: 4 g of hydrochloric acid are dissolved in 300 ml of distilled water, then 3.5 g of sodium thiosulfate is added thereto. After complete dissolution of the components, the solution is added to 1 liter with distilled water. The solution is stored in the dark and in the refrigerator for no more than 1 month.

9. * In conclusion, the plate is washed well with distilled water, acetone and immediately dried with a hot hairdryer at a temperature of 60-70 ° C.

* at the indicated stages, the degree of purification and the presence of bands of pollutants are monitored using IR spectroscopy of moving reflection (Fourier spectroscopy).

Example 2

The method is carried out analogously to example 1, but using the following solution in stage 4, parts by weight:

Distilled water 500

Thiourea 80

Phosphoric acid (85%) 90

Non-ionic wetting Agent rhotoflo 5

The solution is added to 1000 parts by weight. H ₂ O.

Claims (9)

1. The method of restoration of daguerreotypes, including processing the image with a cleaning solution, washing with water and final drying, characterized in that before processing the image with a cleaning solution, the back side and the ends of the plate are mechanically cleaned to the undamaged body of the plate, mechanical cleaning products are removed, and intermediate drying is performed in air degrease the plate, carry out intermediate drying at elevated temperature, followed by treatment with a cleaning solution containing the following components, parts by weight: thiourea 60-80, 85% phosphoric acid 60-90, non-ionic wetting agent photoflo 1-5, distilled water up to 1000 parts by weight, washing with water, then acetone, drying at elevated temperature and edging the plate under the glass. 2. The method according to claim 1, characterized in that the mechanical cleaning is carried out by polishing paste with a cotton swab. 3. The method according to claim 1, characterized in that the removal of the cleaning products is carried out by rubbing with a cotton swab with alcohol. 4. The method according to claim 1, characterized in that the degreasing is carried out by immersion in chemically pure acetone for 1-2 minutes. 5. The method according to claim 1, characterized in that after exposure to the cleaning solution, dimethylformamide with an elevated temperature is immersed in the cleaning enhancing agent, after which the plate is again immersed in the specified cleaning solution for 1-2 minutes. 6. The method according to claim 1, characterized in that they carry out selective brushing of a clarifying solution with a synthetic brush - a 2% aqueous solution of sodium borohydride, after which the plate is washed successively with water and acetone. 7. The method according to claim 1, characterized in that the plate is additionally treated with an oxidizing solution of 8% hydrogen peroxide solution, acidified with phosphoric acid to pH 2 for 5-10 minutes, followed by washing with water and then acetone. 8. The method according to claim 1, characterized in that a protective layer of gold is chemically applied to the image by immersing the plate in an aqueous solution of a monovalent gold thiosulfate complex and keeping it at elevated temperature until a weak golden tone appears. 9. The method according to claim 1, characterized in that the washing is carried out with distilled water.