Preparation of developer by black and white darkroom technology

1. Water should be pure and utensils should be clean.

(Water should be pure water or distilled water)

The water temperature is about 50 degrees Celsius.

(The water temperature should not exceed 53 degrees. If the water temperature is too high, the oxidation speed of the developer will be accelerated. If the water temperature is too low, it is not suitable for the dissolution of the developer. )

3. Be important and accurate.

(When preparing, generally, all kinds of developing drugs are dissolved in 3/4 water first, and then water is added to 1000 ml. )

4. Dissolve in sequence

(The formula is scientific and should be supplemented in order. )

Properly stirring

(stirring should not be too strong to prevent drug oxidation)

Step 6: Filter and store.

(The newly prepared liquid medicine should be used after standing for 24 hours to filter out the impurities formed in the developer) D-76 developer formula (the most commonly used formula)

Water (52 degrees) 750ml

Mi Tuer 2 grams

Anhydrous sodium sulfite100g

5 grams of hydroquinone

Borax 2g

Add water to 1000 ml.

D-23 (particle developer)

Water 750 ml

Mi Tuer 7.5G

Anhydrous sodium sulfite100g

Add water to 1000 ml.

There is a great contrast in this film. It is best to develop with this liquid medicine.

D-72 (photographic paper development) is usually soft and hard.

Water 750 ml

Mi Tuer 3.1g4g1g.

45g anhydrous sodium sulfite 40g 70g.

Hydroquinone 12g 3g 16g

68g anhydrous sodium carbonate 45g 100g

Potassium bromide 1.9 g 1.3 g 3 g stopped developing.

The function of stopping display is to neutralize the alkaline substances remaining on the photosensitive material.

A. After development, although water washing can only wash away the developer on the surface of the emulsion, but not the developer entering the emulsion film, the developer remaining in the emulsion will continue to cause development if it is not completely washed away.

B. the developer is alkaline. If the negatives and photographic paper containing developer are directly put into acidic fixing solution, the service life of fixing solution will be affected.

3. Stop the configuration of liquid

Water 750 ml

Acetic acid 28% 48ml

Add water to 1000ml for fixation. After the film is developed, the unreduced silver halide is washed away, so that the negative film and photographic paper will not change when exposed to light. This chemical reaction process of fixing an image is called fixing.

The formula of fixing solution can be divided into: A simple fixing solution B acidic fixing solution C acidic hard film fixing solution D rapid fixing solution.

When preparing fixing solution, it should also be dissolved in the order of formula.

A. fixing agent

Sodium thiosulfate (soda, hypo)

Properties: Colorless prismatic crystal, easily soluble in water. The silver halide in the emulsion can be completely dissolved, but the exposed silver particles are fixed on the substrate.

Sodium thiosulfate is the most ideal fixing agent. When the content of fixing solution is 25%, the fixation ability is the strongest, and when it is below 40%, 50% means that the fixation ability drops to 5%.

Hypo can be immobilized because it reacts with silver halide to form stable soluble double salt.

B. protective agent

Anhydrous sodium sulfite (sulfur oxide)

Properties: powder, soluble in water.

Its protective effect and mechanism: Sodium sulfite will decompose into yellow sulfur precipitate when it meets acid. Therefore, when preparing acidic fixing solution, it is necessary to add drugs to prevent marine decomposition, which are called protective agents.

C. acetylating agent

Acetic acid (acetic acid)

Properties: Colorless and clear liquid with pungent smell can acidify fixing solution into acidity, so it is called "acidifying agent".

If the fixing solution only has high waves, it will not only have a short life, but also be easy to precipitate and pollute the picture. Because only the fixer of Haibo is neutral and should be alkalized by the developer that comes with the film, the film fixer will continue to develop, so a certain amount of acid must be added.

chemical agent

D. hardening agent

Potassium alum (potassium aluminum sulfate)

Properties: white transparent crystal, astringent taste, soluble in water, basically not oxidized in air.

Features: It can converge and strengthen the structure of colloidal objects. 1. Plastic or metal developing tank

2. More than one scroll of suitable size.

3. Measuring cup

4. dark bag

5. darkroom thermometer

6. darkroom timer

7. Heavy and light film editing

8. Developing basins

9. Film bag

10. Mixing rod for preparing solution