DIY ILFOCHROME CHEMISTRY (Page 3)
basic correction factor which you must add to the factors on each new box of paper.A test strip will soon show the best highlight exposure and maximum black relationship for a commercial developer at the manufacturer’s suggested time, so processing another print made under the same conditions but now using the DPI developer will show the speed and density differences relative to the manufacturer’s system. 1 usually extend my time to four minutes though I have had a few batches of paper which give perfect results at the manufacturer’s standard time.
Colour Correction Test
All ilfochrome paper comes with suggested filtration values printed on the box. These values are arrived at in the factory by testing the paper against a standard light source, in this case the 3200°K normally used in enlargers. Few enlargers give a perfect 3200°K so I always use a colour temperature meter to check the real values and then adjust the light to 3200°K by dialling in the required extra filtration. If this is done, the manufacturer’s suggested filter corrections given on the box should be quite close. This extra filtration is your enlarger’sIn practice, my Durst enlarger generally needs a correction of plus 20 to 30 cyan to reach 3200°K; this is therefore my standard filter correction factor. This factor takes into account the bulb and lamphouse colour reflectance and any output variations due to my rather old voltage stabiliser. When you test your equipment you will probably get different values from mine, particularly if you do not use a stabilised voltage.
As an example, the suggested correction for the box of paper I am currently using (batch 45D301-0410) indicates plus
35Y plus 20M must be used. If we add my plus 30 Cyan correction factor to this we get 35Y + 20M + 30C. Removing an equal amount of unnecessary neutral density of 20 gives us 15Y +IOC which is bang on for most of my slides with this batch. This method has worked with most of the paper batches I have used over the last couple of years, both with standard developers and the home made version given here. This of course also tells me that my formulation is within the specifications required by the paper. It is worth noting that this method also works for calibrating the colour correction values required for Slide Duplicating Film, which also come with a suggested filtration, and are also tested against a 3200°K standard light.Alternative Fixer
neutral rapid fixer - the normal acid paper fixers change the final colour of the print. The colour can be regenerated after acid fixation by soaking the print in a solution of Sodium Bicarbonate or Borax, which of course neutralises the acid pH. This may have some creative uses for abstract photography.
I have experimented with a few alternative fixers, but I have seen no real merit in this. Those who wish to experiment should note that they would need a strongRetouching
Bleaches for Ifochro.ne Papers
Dye Chrome bleaches for yellow, magenta and cyan and a total bleach were once available commercially but I haven’t seen any for some time. i’m told that trade hand retouchers make up their own solutions which! presume to be similar to the formuhe below given to me by friend, the late Julette Soester AMP, a master retoucher. Care needs to be taken when mixing, using or storing these chemicals, some of which can be toxic if handled incorrectly and may now be difficult to get in the UK.These formulae are therefore only given here for the sake of completeness, and are probably only helpful to those that can work under professional or lab conditions. In most amateur situations it may be better to just make another print.