The British Journal of Photography Almanc (BJPA) contained this Ilford advertisment for printing papers available at the start of 1930. 

To see a 1930 Ilford advertisement for Intona P.O.P. paper and an example of Intona paper packaging from around 1920, click here.

Bromide Platinomatt Surface paper – (‘PMS’ paper). Image alongside, courtesy of Michael Talbert.

This Bromide Paper was first introduced in 1897. Notice that it pre-dates the change of company name to Ilford, Limited and is instead being sold by the original Harman company of The Britannia Works Co. Ltd.

Ilford Clorona paper introduced around 1933. Scan sent by "David".

Michael Talbert reports that warm tones on Ilford “Clorona” paper were popular in the 1930s. The Ilford Manual for 1935 gives two print developers, ID-23 and ID-24, suitable for producing warm-black to sepia to red tones on Clorona paper. The Ilford Manual also states that Clorona paper required a negative of “Fair contrast” when brown-sepia to red tones were desired. As the tone of the print changed from brown-black to sepia and finally to red, the visual contrast decreased, so a negative of fairly high contrast usually gave the best results. This is exactly what Michael found in the 1960s using Kodak's equivalent, Royal Bromesko paper.

Ilford Bromide, Selo Gaslight and Selo Contact paper boxes. Images supplied by Michael Talbert.

These boxes have been conveniently dated (25/2/144, 23/8/43 and 25/2/44) and so were products of Ilford during World War 2.

The lowest of the four boxes, labelled S.2 25P is thought to date to the 1930s.

A packet of 4¼ x 3¼ inches i.e. ¼ plate size, glossy, mauve, Printing Out Paper (P.O.P.)

Prior to printing papers like 'GasLight' (see below) and Bromide papers, prints at the same size as the original negative were produced using paper that darkened naturally when left exposed to daylight. This 'self-darkening paper i.e. not requiring a developing process, was originally known as 'Albumen' printing paper, but later became commonly known as Printing Out Paper or P.O.P. This paper was coated with Albumen mixed with ammonium chloride and silver nitrate. Albumen paper was first manufactured from the 1850s (not by Ilford) and a description was first published in 1850 by Louis-Desire Blanquart-Everard. 'Silver by the Ton' tells us (Appendix 4) that P.O.P. was first sold in 1891, a time when Ilford was known as the Britannia Works Co. and became (December 1891) the Britannia Works Co. Ltd.

The date when the P.O.P packet alongside was manufactured is unknown, but since the manufacturers are clearly stated as Ilford, Limited, this implies it was post-1900. It looks to be early 20th century. Glossy Mauve P.O.P was manufactured from 1893. The 'paddle steamer' within the central 'O' is too small to confidently apply a date, though seems to be the earliest registered form of the company logo.

The P.O.P (Albumen) paper was exposed to daylight via a glass negative plate, the two being held in close contact within a contact printing frame. Upper-most within the wooden contacting printing frame would be the frame's glass and beneath that was placed the glass negative plate. A sheet of Albumen paper, emulsion side in contact with the glass plate, came at the bottom of the frame and finally the wooden back of the printing frame was attached to hold the paper and negative plate firmly in contact under spring pressure. In the middle of the wooden back would be a hinge, so that part of the back could be opened to look at the image appearing on the P.O.P. without disturbing or releasing the pressure on the other part. Thus, if the image was still too light, the lifted half of the back could be hinged down again and the exposure continued without any risk of disturbing the registration between the paper and the negative.

Unlike 'development' Contact paper, which was exposed only briefly to bright tungsten light or daylight, the printing frame with P.O.P was placed on a window sill facing the sun, or in strong daylight, for a significant length of time. Every quarter of an hour, or less in bright sunlight, the back of the frame was opened to check on the density of the image on the paper. When the print was judged to have the correct density, the paper was removed from the frame and placed in a bath of plain 'Hypo', aka 'Fixing', solution. 'Hypo' is an old fashioned term for Sodium Thiosulphate (Na2S2O3), originally known as sodium hyposulphate. In this bath of 'Hypo' the silver that had not been exposed to daylight and therefore had not turned grey or black during the exposure, was chemically converted into soluble silver salts that could be washed out of the paper, hence 'fixing' the image. During this 'Fixing' process, the print usually became lighter in tone and so most pictures were exposed until slightly too dark before being taken out of the printing frame and being placed in the Hypo.

After the paper was washed for half an hour to an hour, most prints were then toned in 'Sepia Toner', which gave a rich brown colour to the image and also made the image even more permanent. Note, however, that the P.O.P packet shown here contained Glossy Mauve paper, presumably to obviate the need for sepia toning. 

The Paget photographic company by 1894 was advertising Paget Matt Printing-Out-Paper and challenged Ilford's use of P.O.P. as a trademark. The Ilford company replied that it did not claim to be the sole makers of printing-out paper and had merely registered the mark P.O.P. as having a paddle steamer within the letter 'O'. When printing-out paper was introduced as P.O.P. in November 1891, the paddle steamer occupied the centre of the 0 (as in the image, left). The inspiration for this came from John Howson, Harman's first business manager, whom he appointed in 1889. Howson was a salesman with quiet charm, great originality and considerable initiative. Immediately on joining, Howson started to write and publish Photographic Scraps.

Despite the arrival onto the of market many types (from various manufacturers) of Bromide, Contact and Chloro-bromide "development" papers, P.O.P remained available until the mid-1950s (this date applies to P.O.P in general; the specific production date range applicable to Ilford, Limited, is unknown).

A Selo Gaslight printing paper packet image sent to me by Michael Talbert. He believes the packet dates to around 1940.

Gaslight printing paper was a slow (i.e. relatively light insensitive) paper used for making contact prints. "Contact" prints mean prints made by clamping the negative into close contact with the printing paper, hence the resulting print is exactly the same size as the negative. Such a printing method was frequently used when negatives were large enough (plates or large roll film sizes) to produce worthwhile 'same-size' prints. But the advent of miniature 35mm film cameras mostly made such a printing method obsolete and such small negatives were printed by projection using an 'enlarger' to yield a useful sized image.

The name Gas Light refers to yellow coloured light, as produced by 'Towns' gas when burnt in gas mantles for home lighting. The paper was largely insensitive to such light and so contact printing could be carried out in what was, until the 1930s, normal household room gas lighting. But the term (and the paper type) persisted into the electric light era (as with this 1940 packet), though it was necessary to take more care to shield the paper from direct light when using it in a room lit by electricity. By the 1950s, this type of slow, silver chloride based, printing paper was (correctly) renamed as Contact Printing Paper.

The pack of paper shown here is of ¼ plate size (3¼" x 4¼") of Normal contrast grade, single weight (i.e. thick paper rather than card) and with a glossy surface (though requiring glazing to bring out the full glossy potential. Glazing involved squeegeeing the wet print (from its final wash) onto a sheet of glass and allowing the print to dry. With luck (!) the print would fall off the glass when dry and would have a perfect mirror glossy finish. Commercial printing laboratories used heated chromium glazing sheets rather than glass.

The code on the packet is S31P, which is odd as the paper is labelled as Normal grade, while 3 usually refers to a Hard or Vigorous grade.

Perhaps the 'Changes in Gradation' shown above explains the anomaly. It seems that post-1945 Ilford changed their printing paper contrast range such that the previous Grade 3 (vigorous) became named 'Normal' with a Grade 2 designation. The packet shown here seems to fall into the transition period when both grading nomenclatures were in use

Further images of Selo Gaslight printing paper (below), from this same era, have come to me from Bob Hindley.
He says "I attach some photos which will probably interest you. They are of an item I bought at a car boot sale earlier this morning (Feb 2015). It was very expensive - 50p".

The stamp on the back says County Borough (of) Halifax, 24 Sep 1938, Alien's Department.
"From what I can glean from the web, the Alien's Department must have been responsible for registering foreign nationals.
You'll see that the code is S41P and it's hard, glossy, single-weight".

The unopened packet of Selo Gaslight paper shown below, 12 sheets of 3½ x 2½ inches 'soft' glossy single weight paper, was purchased by the author at the Wolverhampton Camera Fair on 6th October 2024.
It was originally intended for making contact prints from contrasty negatives, likely to have been taken using a box camera giving 8 exposures on either a 620 or 120 size roll film. The packet likely dates to around 1940.

Notice that it was sold by J.Lizars, Photographic Dealer of 101, Buchanan Street, Glasgow. It was priced 6d (6 old pence = 2.5 new pence). The J.Lizars business appeared annually in the 'Directory of the Photographic Trade' listed in the British Journal Photographic Almanac (BJPA) until 1943, proclaiming various addresses including 381, Sauchiehall Street, Glasgow, but 101-107 Buchanan Street seems to have been their Head Office.
See this Wikipedia site for some of the early history of J.Lizars.

From Michael Talbert
The table opposite shows lists all the surfaces, weights, grade numbers and codes of Ilford Bromide paper as at (it is believed) 1940.

The table was printed in the book “Selo Text Book of Amateur Photography”. There were six contrast grades of glossy single weight (code P) paper at that time and an amazing choice of paper surfaces.

Below is a similar list from (believed) the early 1950s. The range of surfaces and grades had reduced by then.

Below: An August 1966 (H66) packet of Ilfobrom paper, Glossy, Grade 2 (Nromal), Single Weight.

Right: A May 1972 (E72) packet of Ilfobrom paper, Velvet Stipple Grade 2 (Normal), Double Weight.