If the first test is grossly over or under exposed it is better to correct for density before attempting any colour balance correction. A heavily over-exposed print with a cast can show a correct balance when the density is put right. When you are fully satisfied with the appearance of the test print go ahead and make your final print . . .

When masked negatives (such as Ilfocolor or Kodacolor) are being printed, the cyan basic filter must be placed over the negative during all operations. This serves to even out the exposure ratios which would otherwise be affected by the orange coloured mask.

I made tests with Kodacolor, Gevacolor and Agfacolor negatives and in each case the final print was satisfactory.

Several points arose during the tests which may be of interest. The filter holder, for example, is designed to clamp on to the lens barrel so as to make it suitable for any enlarger. If only one enlarger is to be used it would be far better to attach the filter holder to the enlarger's red focusing-filter stem by a small bracket, so that the lens aperture can be altered without removing the filter holder. The basic cyan filter is made to fit over the negative carrier. Any dust or marks on this filter will therefore register on the paper when the lens is stopped down. The basic filter should be mounted over an aperture in a piece of black cardboard cut to fit on the enlarger's condenser or diffusing screen.

Now a black mark for the manufacturers! Every sheet of paper in the kit supplied to me had a deep score across it - in the same position in each case. They will need to do better than this if they hope to sell colour paper on a highly competitive market! And is it entirely necessary to supply only ten sheets of paper per kit when the solutions will process twenty ?

Nor can I agree with suggestions regarding processing latitude. Under-exposure and overdevelopment - which is what processing at 85F amounts to - can cause many failures with colour materials due to the inherent softness of the emulsion, colour casts caused by crossed characteristics etc. I know that this is done commercially but I would suggest that it is better for the amateur to stick to his well-tried 68F processing and obtain the slight variation in contrast possible by developing from four to six minutes, with four as a standard.

The basic exposure for the calculator I found in all cases to be sixty seconds and not thirty seconds as stated in the booklet. This would halve all the factors given in the table for example, for two minutes basic exposure, the times would be multiplied by two instead of four. Otherwise - full marks.

At £4.17s.6d (£4.88p) for a complete colour printing system it is remarkable value for money. Cost per print depends on the number of tests necessary. Assuming, for a start, that two sheets of half plate paper are used to produce one half plate print, the cost is about 4s.9d (24p) per print; but as more experience is gained this will be reduced to 3s.6d (18p) or less. If a whole roll of negatives has been exposed at one time under the same conditions, it should be possible to print the whole roll with a test on only one negative - in which case the cost will be about 2s.8d (13p) per print. This compares extremely well with a commercially-produced half plate at an average price of 9s.0d (45p) - which in all probability may not be as satisfactory as the one you produce yourself!

Is the process efficient ? Well, I started mixing the chemicals at 1 p.m. on Saturday, then set up the enlarger and had a satisfactory print by 4 p.m. - and I had never even heard of the kit before the previous evening, when the editor sent it to me for reviewing. And in all cases, and at every step, I tried to forget any previous knowledge of colour processing and follow only the instructions provided. Have a go! You will not regret it, and you will have taken the first step in a fascinating new field of colour work.

K. A. LOMAX

The PATERSON COLOUR PRINT KIT
"Experiment with new 'quick-way' printing"
WELL, IT HAD TO HAPPEN sooner or later, and at last the patience of the amateur colour enthusiast is rewarded. The Paterson Colour Print Kit enables anyone to make his own colour prints with any type of enlarger, and with a total processing time of only seven minutes ...

More than just a new print process, the Paterson Colour Print Kit is a complete colour printing system - the Pavelle system - centred round the ingenious Pavelle-Theilgaard Exposure Calculator.

This simple little gadget enables one to obtain the first test print with the minimum of paper and delay. But let me make one point quite clear; there is no device available - at any price - which will assess any negative for exposure and give the necessary filtration factors right off the cuff . . . except by sheer coincidence ! When the best results are aimed at, there is no substitute for a test print. What these devices will do, however, (including the Pavelle-Theilgaard Exposure Calculator) is to provide the basic exposure for this test print with the least trouble.

It consists simply of three coloured step-wedges - red, green and blue - in a book-form carrier accepting a piece of paper 3x2in., and a fourth column containing a series of numbers from 1 to 48. Its method of use I will explain a little later.

The Paterson Colour Print Kit consists of the exposure calculator with its associated diffusing screen, a filter holder designed to attach (by four rubber-tipped set screws) to the enlarger lens, a set of red, green and blue printing filters mounted in a card slide, a basic cyan filter for use when printing masked negatives - such as Kodacolor - a safe-light screen, a packet of ten half-plate sheets of Pavelle colour paper and the necessary developer, stop bath and bleach-fix chemicals in powder form. There is also a comprehensive instruction manual which gives a certain amount of colour printing theory as well as instructions on how to use the kit.

Although each operator will, in time, develop his own printing technique, perhaps it will help the less experienced if I describe the way I used the Paterson kit for the first time, taking a Gevacolor negative as an example; and assuming, of course, that the chemicals have been made up according to the instructions.

Starting point
Focus the negative at full aperture to half-plate size on the baseboard, then stop down to flu. Now attach the filter holder to the lens - taking care not to alter the aperture - and lay in it the plastic diffusing screen. Although a safe-light screen is provided in the kit I have never used one when colour printing, and prefer to carry out the following steps in total darkness.

Take a piece of half plate paper from the packet and cut it into quarters by folding it in half, then in half the other way, tearing across the creases. Insert one piece in the Pavelle-Theilgaard Exposure Calculator and place in the centre of the image area of the masking frame, filter side up.

You will find a paper-clip handy to hold the calculator closed when the paper is in it. The other three small pieces should, of course, be returned to the packet which, incidentally, I always keep in a whole plate box. Switch on the enlarger and expose for exactly sixty seconds.

I use a shielded torch for timing this - about a quarter inch aperture covered with two layers of red or green paper - and a stop watch. These are under the enlarger table with the enlarger switch down on the floor.

Still in total darkness, develop the exposed paper for four minutes at 68F; stop-bath for one minute, and bleach-fix for two minutes.

The room light can now be switched on and the test piece washed until the base is white - two or three minutes under the tap. This 'print' will have on it a list of numbers and a yellow, magenta and cyan wedge each marked with the initial letter of the filter used to produce the image - B, G and R for the blue, green and red filters (see illustration - above). Look for the lightest step of each colour which is fully covered; and note down the corresponding numbers from the numbered column. These are the exposures in seconds for each of the three printing filters.

With some types of negative it is necessary to apply a correction factor to one of the exposures - these are listed in the instruction book, but in the case of Gevacolor I found that correction was unnecessary.

Now remove the diffusing screen from the filter holder and insert in its place the filter slide with the red filter in position under the lens. I always expose in the sequence red, green, blue - not the reverse recommended in the instructions. In practice I suppose it makes no difference at all.

Back into darkness . . . place a second quarter sheet of paper on the baseboard where an easily recognized colour will record. This must not be a heavy or bright colour (such as a post box) but a hue which is known to be a near neutral; or a flesh tone. This is to enable subsequent corrections to be made more easily.

Expose through the red filter for the appropriate time. Now carefully slide the filter holder across until the green filter is in position. This must be done by touch alone, but as the slide is notched it is quite easy. Expose for the green filter time and repeat for the blue filter time. A point worth noting is that the lens aperture should be set so that no exposure is less than ten seconds. A half-second error in ten is only 5 per cent - but a similar error in two seconds would be 25 per cent, which would greatly affect the colour balance.

Process the paper exactly as you did the initial test . . . then examine the result.

Only experience . . .
From here on it is a case of experience, which can only be gained by practice. The print may look correct or it may show an error in density, colour balance or both. The skill in colour printing is to know just how much of what kind of correction to apply. The instruction manual deals with this point sufficiently to provide a basis for experiment.

Having assessed any necessary correction it is advisable to expose and process a further small piece of paper before making the final print. This will serve as a check on your judgement and calculations and should avoid wasting a full sheet of paper if at fault.

The description alongside of the Paterson-Theilgaard Calculator, is taken from the booklet "All about Printing Colour Negatives", by Felix Smith.

The scale on the calculator reads 1, 1.3, 1.6, 2, 2.5, 3, 4, 5, 6, 7.5, 10, 12, 15, 19, 24, 30, 38, 48.

The Paterson Colour Print Kit, as it stands, is probably the cheapest way for the amateur to produce his own colour prints, but it is obviously even more worth while if he can reduce the initial cost, and that of replacements, when these become necessary.

Each part of the kit is available as a separate item, so it is possible to build up a print process kit by purchasing only those items which cannot be made easily or cheaply and by using substitutes for the others. Taking the items of the kit individually we can easily see where a suitable adaptation can save cash.

For the printing filter holder, for example, all that is really required is a light metal or cardboard attachment which will fix to the enlarger's red swing-filter stem, and carry the printing filter slide.

The printing filters can be mounted in a simple slide cut out of cardboard -¦ I used an old print mount - and painted matt black. Two pieces of card each measuring 6.5x2.25in. are required. In each piece cut three holes 1.5in. square, equally spaced along the card. The three filters are held sandwiched between the cards, and notches are cut in the edge of the assembly so that each filter in turn can be correctly centred under the lens in the dark.

Starting point
The filters I recommend are the Wratten 29 (red), 61 (green) and 47B (blue), costing 2s.6d each, as 2 in. gelatin squares.

Apart from the red, the filters supplied with the Paterson Kit are not sufficiently narrow cut to produce the best print possible from any given negative; the blue filter in particular transmits a large proportion of unwanted green, therefore tending to overlay the yellow with magenta.

When the Wratten narrow-cut filters are used, the exposure times determined by the Theilgaard exposure calculator must be modified, and I have found a good starting point is obtained by doubling both the green and blue times given by the calculator.

The basic filter - used when printing masked negatives such as Ilfocolor and Kodacolor - is effectively replaced by an Ilford 803 cyan.

Although substitutes can be made for the Theilgaard exposure calculator and its associated diffusing screen, the use of an electronic densitometer would be required for easy calibration. These two items are much better bought, and together cost 22s.1d. (£1.10p)

The Pavelle paper must, of course, be bought and the most economical size is undoubtedly 10x8in at 33s.2d. (£1.66p) per packet of ten sheets. One sheet will cut into twelve pieces for the exposure calculator, or four handy-sized en-prints.

Excellent results
Apart from the paper, the items requiring most frequent renewal are the processing chemicals, and I have had excellent results from the following formulas:

Developer
Stock Solution A
Droxychrome 25g
Potassium Metabisulphite 6.5g
Water to 125cc
Stock Solution B
Sodium Sulphite 5g
Sodium Carbonate 200g
Hydroxylamine HCl 5g
Potassium Bromide 1.5g
Water to 1litre
Use, 1 part A, 16 parts B & 23 parts water.

To make up a working solution direct, the formula is:
Droxychrome 5g
Sodium Sulphite 2g
Sodium Carbonate 80g
Hydroxylamine HCl 2g
Potassium Bromide 0.6g
Water to 1 litre

Although the Paterson developer appears to contain rather more Potassium Bromide than the substitute, I prefer the prints produced by this formula.

Stop Bath
5 % solution of Potassium Metabisulphite. Bleach/Fix
Water 350cc
Amfix 150cc
Iron Sequestrene 65g
Sodium Carbonate 8g
Potassium Bromide 25g
Water to 600cc

Two points worth noting. If Pavelle prints are to be glazed, we find that a ten-minute soak in 10 per cent Formalin solution - followed by a brief rinse - is a great advantage in hardening the emulsion; and also helps to stabilize the dyes. And finally, the Theilgaard exposure calculator will, of course, work with any other process; so that if - for example - you are already printing Ektacolor or Agfacolor by additive filters, this calculator alone can save hours of time in assessing negatives.