This section is from the book "Modern Photography In Theory And Practice", by By Henry G. Abbott. Also available from Amazon: Modern photography in theory and practice: A hand book for the amateur.
After all prints come from the hypo bath, it is necessary to handle them through at least two waters by hand, before putting them in running water or the washing box. By doing this you wash off the surface hypo and also little air bubbles that sometimes fasten themselves on the print and hold the hypo under them, allowing it to go on bleaching, thereby getting little white spots on the prints when they came from the wash water, that were not there when they were fixed. After two waters by hand, one hour in running water, or ten to twelve changes by hand, is sufficient washing.
Red spots on paper can come from a number of causes. The most common forms are finger marks, bubbles and preservative chemicals still in the paper. When from finger marks, they can be easily recognized. When the spots are round or oblong and have defined edges, they are from bubbles and can be avoided by sliding prints in the first water and knocking them off. If the red spots are uneven and scattered over the paper, or if the prints act as though they were greasy when they are in the washing water, the trouble comes from oil or grease, which may come from the hands, trays, or water. This trouble can be overcome in both Platino and Junior paper by adding three ounces saturated solution of sal soda to the first water prints are placed in (3 oz. saturated solution of sal soda to each gallon of water), handling prints over in this water for five minutes. This alkali cuts off all oil or grease on the prints and neutralizes the acid preservative chemicals in the paper, the six changes of clear water afterwards washing out all traces of the alkali and bringing your prints up to the gold bath in a perfectly neutral condition. If you find 3 oz. saturated solution of sal soda is not enough, put in a couple more or enough to do the work.
When paper prints brown or muddy-looking in the winter, the paper is too fresh and should be put in a warm place (near a radiator) for a few days. Paper treated in this way will soon print a rich red color. Fresh paper must be printed darker than old paper. When paper prints a weak red color in the shadows during cold weather, it is because it is chilled and the chemical action does not take place freely. Always print in a warm temperature if you wish the best results. In the winter, paper thirty days old is much better than very fresh, older paper giving stronger and richer prints than fresh paper. Bronzing in the shadows is generally caused by not toning the shadows properly in the gold bath first and not far enough in the platinum bath afterwards. Blisters are caused by a change of temperature in the baths or water and they usually come in the hypo or afterwards. Adding fresh hypo will reduce the temperature of the water. Putting the prints in cold hypo bath and from there into warmer water again is what brings on blisters. It can be helped by throwing prints in a salt water bath after hypo, but the best plan is to temper the hypo or keep it in a saturated form and reduce it as you need it. Another plan is to gradually reduce the hypo bath by pouring off part of it and adding water, repeating until down to clear water.
When sodas come from chemical works in crysta form, they contain a very large percentage of water of crystalization and the conditions under which they are kept have a great deal to do with their strength. If they are kept in a warm dry place, the water of crystalization dries out and they become much stronger. When sodas are weighed by scales, you can never tell anything about them. Always test all sodas in solution by hydrometer. It is well to often test your hydrometer by washing thoroughly and filling with plain water. If the stem stands at zero in the water, it is O. K. If it sinks below and tests stronger, it is "off;" to remedy, tap the small end of the hydrometer on a board and jar the paper in the stem down. Keep testing it until it is at the right point.
One of the most important things in a toning room is litmus paper. Only buy the best, put up in glass tubes. Never allow any one to sell you a litmus paper that has a hard, solid body. Always use a soft litmus paper that the solution can take hold of at once. Use red litmus paper to test for alkali and blue litmus paper to test for acid. The length of time it takes to turn red litmus paper blue, or blue litmus paper red, will denote how strongly alkali or acid the solution is. Always keep in well stoppered bottles, as light or air will affect the sensitiveness of the litmus paper; and never mix the blue and red.
The water we use is of the greatest importance and there is entirely too little attention given to it. After having tried the water over the larger part of the United States, we find lime, magnesia, plaster paris, sulphur, iron and many other things contained in the water we use. When we remember that toning and developing are very delicate chemical operations, it is a source of wonder that the results obtained are as good as they are. When a gold bath is made with water that is strongly alkaline the prints will be muddy and flat and lack brilliancy and in the platinum bath the results are even worse, precipitating the platinum, causing slow toning and a waste of materials. In the hypo bath it is often the cause of yellow whites. It is very important that we clear the water of these chemicals as far as possible, if we desire to obtain the best results. A very simple and easy way to do this is to get an empty whiskey or alcohol barrel, remove the head, clean thoroughly and fill with water. Dissolve a teaspoonful of ground alum in a cup of hot water and pour in the barrel of water. Stir thoroughly and allow to settle for 24 hours. Use this water for first washing, for baths and all washing between baths until after the prints come from the hypo, when they may be washed in the regular tap water. There is very little water west of the Mississippi River that could not be improved by this treatment, especially where it comes from artesian wells. When water is heavily charged with magnesia or iron, it is best to use other water until prints are out of the hypo. Any trouble you may go to in your efforts to obtain pure water will pay you a hundredfold in time, material and results and this means money.