Synthacolor (British Synthacol Ltd; Rowsley Works, Reddish, Stockport) were probably the first organisation within the UK to announce a home developing and printing outfit for colour negative film. The date was September 1953 (ref: Photography magazine, September 1953).

Because of their earlier entry into home colour film developing and printing, the BJPA contains various Reviews, starting in 1954.

The film processing kit comprises four solutions, supplied as powder chemicals packed in five tins, each making 1 litre of solution each with the exception of the intermediate stop bath which makes 2 litres. The four solutions are the colour developer, an intermediate bath, a bleach bath, and a final fixing bath. It will be seen that a combined bleach-fix, such as is commonly used for the processing of colour negative materials, is not supplied (but see the BJPA 1956 test of the new Synthacolor kit, below).

All the chemicals dissolve readily and the solutions may be made up quickly; the colour developer however, as is usual with such solutions for colour negative materials, must be allowed to stand for twelve hours before use.

Comparative tests were made on the three makes of colour negative available to determine the colour balance and gradation given by the Synthacolor negative processing kit and the official processing chemicals or service offered by the manufacturer. In each case the Synthacolor kit gave extremely similar results to those given by the official processing both as regards colour balance and the gradation of the negatives. For the Pakolor negatives a somewhat different filter pack would be needed for the two differently processed films but this change would not be greater than the normal amount of filter correction needed.

Thus the Synthacolor colour negative processing kits are a most useful product and provide the photographer with an alternative source of processing solutions at reasonable cost. All the components of the kit may be obtained separately, a useful point since it is not advisable to use the colour developer and intermediate stop bath more than once, whereas the bleach and the fixer will handle a fair quantity of film before exhaustion."

"Synthacolor paper is a colour positive material of the conventional type for the making of prints from colour negatives either by contact or by enlargement.

The printing kit comprises a supply of the paper in 3½"x 2½" size, 36 gelatine colour correction filters, and a glass filter (named as the 'R' filter) which gives a basic modification of the colour temperature of the light source. The colour correction filters consist of 3 sets of twelve filters, yellow, cyan and magenta in density steps of 0.05 from 0.05 to 0.60. Since the paper, like any colour printing paper, is panchromatic, it has to be handled in the light of a green safelight of low brightness, though the amount of light which it passes is appreciably greater than a normal panchromatic safelight screen. All the chemicals except the stop bath are supplied as powders which make 1 litre of solution. (Because the processing sequence incorporated two stop-baths, it is likely that the stop-bath liquid concentrate was diluted to make 2 litres, one litre each for the two Stop Bath steps).

After the first fixer the green safelight may be changed for a much brighter orange or yellow-green but the print cannot be viewed in white light until after the final fixing bath. The complete processing routine takes some 59min. and a test print can be assessed for colour balance after some 39min.

The recommended light source for the enlarger or printing box is a standard high intensity enlarging bulb and the basic correction filter, called an 'R filter', has to be inserted into the light path".

The following notes are from Michael Talbert.
Synthacolor 'R filter'
The Synthacolor 'R filter' is thought to have been a heat-absorbing glass to prevent a strong cyan in the prints caused by heat from the enlarger lamp affecting the red sensitive layer. Without the 'R filter' the red exposure in Tri-Colour (additive) printing would have been far too short compared to the green and blue exposures. In White Light (subtractive) printing, very high value cyan filters would have been needed to eliminate a heavy cyan cast to the print, thus increasing the print exposure.

Test Exposures
A test exposure could be made on a black and white Bromide paper first, before exposing expensive colour paper. An initial exposure was made on a Normal grade Bromide paper, which was developed for 1½ minutes in a suitable black and white print developer. Suggested paper/developer combinations were Kodak Bromide paper WSG 2S developed in D-163 developer, or Ilford Bromide B2-1P developed in ID-20 developer. The paper codes indicated that both recommended papers had a glossy surface.

A stepped (e.g. 5secs, 10secs, 15secs, 20secs) exposure test strip would give the best results if the 'R filter' was left in place in the filter draw. From this black and white test strip the correct exposure could be easily seen. Then, since the Synthacolor paper had a similar speed to the recommended black-and-white bromide papers, the same exposure time could be used for a no-filter print on the colour paper. Some strips of clour pper, for such tests, were included in the packets of Synthacolor paper. If the enlarger was connected to a voltage stabilizer the correct voltage was checked before exposing the black and white test and rechecked before exposing the colour test. The processed colour test strip was examined in daylight or under fluorescent lighting and its colour balance assessed.

The Synthacolor printing paper was balanced for unmasked colour negative films. Comparing printing from a masked (orange-red) Kodacolor negative onto Kodak Ektacolor paper, where it was extremely likely that only yellow and magenta printing filters would be required to correct any colour cast, with Synthacolor paper it would often be required to use cyan printing filters. For example: a filtration of 20 Yellow plus 40 Cyan would eliminate a greenish yellow cast. Similarly, Magenta plus Cyan filters would correct a blue cast, making the print more yellow.
(Reference: Colour Prints, J.H.Coote, 1956, Focal Press).

As British Synthacol did not manufacture their own brand colour negative film, their printing paper must have been balanced for printing from average unmasked colour negatives as were produced from all the colour negative films available in the UK in the early to mid-1950s. Agfacolor, Gevacolor, Pakolor, Raycolor and Ferraniacolor films were generally obtainable (though other makes were available but not sold in the UK); Kodacolor did not appear in the UK until 1957. If the colour printing paper was balanced for an average colour rendering from a variety of unmasked colour negative films, it would not have been possible to obtain the best colour prints from every make of colour negative film on the market. An Agfacolor negative would generally have given a better print when produced on Agfacolor CN 111 paper because the colour dyes in the processed negative film would have better matched that paper; both the film and the paper being made by the same company.

The 1954 BJPA concluded:
"Prints of similar quality to those made on any other colour paper can be made on the Synthacolor material and it would seem possible to print from any of the three types of colour negative films currently available (at that time) using correction filters within the normal range. As with all materials of this type, care in processing is needed if the whites of the print are not to be degraded with a colour stain.

The paper is available in both 10 and 25 sheet packets in 3½"x 2½" and 6½"x 4½" sizes only. All sizes and packings are on a double-weight base. The green safelight, Synthacolor No.1, is available in 7 x 5ins, 10 x 8ins and 12 x 10ins sizes and replacement chemicals for all the baths in the processing kit may be obtained."

Synthacolor paper processing sequence from 1953
This first processing sequence was for processing prints by hand in open dishes, since sophisticated drum and tank type colour processing equipment hadn't been invented at that time (one of the earliest was the Goodman; In 1959 'Blackadder' of 11-13 West Nile Street, Glasgow, C.1 advertised their 'Goodman Colour Tank' for "full colour print processing in room light conditions ~ economical with chemicals" for 49/6d = £2:47.5p).
In recognition of the kit being intended for simple (by hand) dish processing, the temperature was a more normal room temperature (68°F = 20°C) than the elevated temperature processes that came along later from Kodak and Agfa.

The first five steps to be carried out in the light of a Synthacolor No. 1 green safelight filter. The BJPA kit description above says "the amount of light which the safelight passes is appreciably greater than a normal (camera b&w film) panchromatic safelight screen."

Step	Solution	Time (mins)	Temp (°F)
1.	Colour Developer	8	68 (=20°C)
2.	First Stop Bath	3	65 – 68
3.	Second Stop Bath	3	65 – 68
4.	Wash	4	65 – 68
5.	First Fixer	5	65 – 68
Print can be examined by the light of an orange or a yellow/green safelight
6.	Wash	5	65 – 68
7.	Bleach	2	65 – 68
8.	Wash	5	65 – 68
9.	Second Fixer	4	65 – 68
White light can be used
10.	Final Wash	20	65 – 68
11.	Dry

Total time excluding drying: 59 minutes.

Notes:

1. The contrast of the print could be varied slightly by altering the development time between 6 and 8 minutes, the longer time giving more contrast.
2. The safelight filters mentioned for use after step 5 were possibly filters used for black and white printing papers. At that time Kodak UK made a Series 0 filter, orange, for use with Bromesko paper, and had recently introduced a yellow/green coloured filter, Series OB, for use with all their black and white printing papers. The Ilford equivalent was a No.902, described as “light brown”, or nearly orange, for use with their Bromide and Plastika papers.
3. It is thought that the Second Stop Bath acted as a Hardening solution.
4. It seems this processing sequence did not include an Anti-Fade bath, or Stabilizer.
5. Synthacolor paper was for use with unmasked negatives only, Agfacolor, Pakolor, Gevacolor and the later Raycolor negative film. ICI color, a masked colour negative film, was on the market in the mid-1950s, but was used mainly by professional photographers and had it’s own colour printing paper.
6. Most of this information is taken from the British Journal Photographic Almanac of 1954.
7. It is likely that the development temperature had to be kept within the limits of +/-½ degree Fahenheit, or at least +/-1 degree Fahenheit, although it does not mention this in the B.J. Almanac.

Compared to the 1954 Synthacolor kits reviewed above, in 1956 Synthacolor are claiming that their home colour kit has:

• reduced number of chemicals (3 including Bleach-Fix, instead of 5),
• dual purpose suitability for developing colour negative film as well as colour printing paper,
• only 25mins. before the print can be examined (albeit by artificial light) compared to the previous 39mins.

The BJPA reported:
This new processing kit is designed to process the colour negative films and papers that are generally available.

The kit offered a considerably simplified processing schedule for both films and papers since it now incorporated a combined bleach-fix solution; in addition the developer was so formulated that it was made up as three stock solutions which could be mixed in differing proportions for films and paper.

The developer pack contained sufficient to make 84 fluid oz. of the necessary stock solutions, the stop bath enough to make 35 fluid oz. of stock solution (which diluted to make 10½pints = 210 fluid oz of working solution), and the bleach-fix made 70 fluid oz. of working solution.
Price of the outfit was £1. 13s, and the individual components were available separately at l0s. 6d. for the developer, 2s. 6d. for the stop bath, and 19s. for the bleach-fix.

Synthacolor paper processing sequence from 1956
Michael Talbert suggests the following as the processing sequence from 1956. It was shorter and included a combined Bleach-Fix solution. It was intended for print processing in dishes, or using the newly available “Goodman” tank (see above). The first four steps to be carried out in the light of a Synthacolor No.1 safelight filter, an olive green colour.

Step	Solution	Time (mins)	Temp (°F)
1.	Colour Developer	6 - 8	68 (=20°C)
2.	Stop Bath	2	64 – 68
3.	Wash	5	64 – 68
4.	Bleach-Fix	8	64 – 68
After 4mins in the Bleah-Fix, artificial white light could be used to inspect the remaining process.
5.	Wash	15	64 – 68
6.	Hardener-Stabilizer	5	64 – 68
7.	Wash	5	65 – 68
8.	Dry

Total time excluding drying: 46 – 48 minutes

Notes:

1. The safelight used for the first four steps was a Synthacolor Olive Green No. 1 safelight. It had to be used with a 10 to 15 Watt bulb and kept at least 4 feet from the processing dishes. Safelight fogging showed up as a pink stain in the highlights of the print.
2. The Colour Developer was made up as three stock solutions and the working solution was made up by taking quantities of these three solutions, A, B, and C, diluting with the correct quantities of water. This was similar to the method of making up the working solution of the Pavelle P-100 and P-200 colour developer, where two stock solutions were mixed in the ratio of 10 to 1.
3. The Stop Bath was made up as a stock solution and was diluted before use, and the Bleach-Fix was made up as a working solution.
4. The Hardener-Stabilizer was made to the formula of 20ccs of 40% Formaldehyde solution to 1 litre of water. The Formaldehyde solution was not included in the processing kit.
5. All solutions could be used immediately after they had been made up but it was said that it was an advantage to leave the developer to stand for 12 hours before use.