Hey guys. When did the RAF change from Night Black which was like soot to Night Black smooth? I also know of the Night Black which had a sheen to reflect searchlight beams, but unsure of its use

The official date that "Special Night" was abandoned was 19 October, 1942, but of course for units in the field the actual date could have been later than that. Suffice that by the end of 1942 Special Night was effectively gone.

Ok thanks Jessica. I knew that was just reminding myself with the post. If you know what I mean?

At a conference held at the Air Ministry on 13th February 1936 a decision was made to develop a suitable camouflage finish for use on the under surface of Coastal Area Flying Boats to render them inconspicuous in the glare from a searchlight or flare.

The task was delegated to the School of Naval Co-operation in partnership under the supervision of the RAE. A matt black finish, Y.B.L.4. already existed. This had a very matt finish when freshly applied but the Carbon Black pigment was so soft that with a little rubbing it became glossy and this was considered unsuitable if used by itself. Laboratory tests showed that mixtures of Carbon Black and harder Ultramarine pigment produced a finish which offered not only low reflectivity, but were also quite durable. Full scale comparative tests between Y.B.L.4. (Carbon Black pigment); Blue Black (made from Ultramarine and Carbon Black pigments); and dark blue (made up of Ultramarine pigment and black dye) and Dark Green were made by applying them to aircraft which were then illuminated by searchlights.

The necessary trials began in late March and continued into April 1936 with the results of the experiments being submitted to the Air Ministry in an RAE report during the first week of May 1936. This report concluded that of the four finishes, the blue black, on account of its greater hardness, was considered the more serviceable and no further developments were recommended.

On 8th May 1936, the Air Ministry asked the RAE to submit 12 samples of 'Night' which were dispatched on 26th May 1936. On 10 June 1936, the RAE received a letter which along with other matters suggested that besides the under surfaces, the new 'Night' shade would also be convenient for the identification lettering on the camouflaged upper surfaces and as an overall
finish on the airscrews.

The beginnings of the development of Special Night are a little obscure. In late February or early March 1939, Professor T R Merton and Sir Henry Tizard visited the RAE. Whilst there, Professor Merton saw a copy of an ADEE report, No 928 which the RAE originally submitted to the Royal Engineers Signals Board of the War Department at Regents Park Barracks, which dealt with the visibility of a camouflaged aircraft when observed in
a searchlight beam.

Apparently thinking better results could be obtained than those in the report, Merton went away and produced a very matt black finish using a material called optical black which is used to line the insides of optical intruments. The sample was given to Tizard who in turn sent it to
A H Hall, the Superintendent of the RAE, who in turn passed it to Dr Ramsbottom, head of the Chemistry Department.

Hall returned the sample to Tizard on the 24th March 1939, with a covering letter prepared by Dr Ramsbottom on the subject of matt black surfaces outlining the research work done by the RAE and the present state of the art.

On the 28th March, A E Woodward Nutt wrote to Merton about his own visit to the RAE the previous Friday. ln the letter, Woodward Nutt went into some detail of the problems encountered in producing an effective aerodynamically smooth anti-searchlight finish. He considered that as the current Night finish absorbed 95% of the light falling on it, any improvement in the finish must be in trying to reduce the remaining 5%.

At the time, none of the aircraft painted in the Temperate Land and Night Scheme were used purely as night bombers, so any resulting improvement had to be suitable for both day and night operation. For this reason, the most obvious expedient, extending the Night finish up the fuselage sides and onto other parts of the airframe was looked on with disfavour because this would compromise the camouflage effect of the Temperate Land Scheme by day. Woodward Nutt also considered that any improved finish would have to take into account the need for such a finish to stand up to the wear and tear of service life whilst remaining aerodynamically
smooth to the order of the surface roughness of not greater than the 1/1000 of an inch then being obtained on production aircraft.

Because the latter two points were the major sticking points encountered during the development of the original Night finish, with the problem being of paint technology rather than physics, Woodward Nutt was of the opinion that the best way of securing a really substantial reduction in visibility was most likely to be obtained by persuading the Air Staff to employ certain aircraft solely for night operations and to paint them Night overall rather than to increase the blackness of the parts of the aircraft

ln his reply the nex day, Merton gave his own opinion that he still believed that a substantial reduction in the amount of light reflected, especially at high angles of incidence would be
possible if a small sacrifice in speed was considered worth while as this would reduce the chances of being seen and therefore reduce the number of casualties.

On the 31th March, Woodward Nutt wrote to Merton suggesting that Merton should discuss the matter with Dr Ramsbottom and offered to arrange a meeting, contacting the RAE later the same day. He also appears to have raised the subject at the 47th meeting of the Committee for the Scientific Survey of Air Defence on the13th April 1939.

At this meeting the Committee were informed that Professor Merton had been looking at the question of 'blackness' of the standard Night finish as currently applied to the undersides of bombers, and felt that if some of the current standards with regard to durability and smoothness of finish could be relaxed, a very much blacker finish could be obtained. The Professor then produced samples of metal painted with the standard Night finish and a blacker finish for comparison. He thought that it might be possible to produce a very black finish which could be applied quickly before a raid and which need only last for the duration of that raid. The resulting camouflage finish would thus be temporary and not compromise the daylight camouflage of the aircraft. It was pointed out that if a reduction in visibility from the air as well as the ground was required, it would be necessary to apply this finish overall instead of only the undersurfaces as at present.

After some discussion the Committee recommended that in view of the importance of reducing the visibility of bombers at night, Professor Merton should discuss with the appropriate department of the RAE the practicality of producing a very black finish if the present requirements for durability and smoothness of finish were relaxed. In the event that such a finish should be evolved, the Committee also recommended that it should be applied
to a service aircraft so that a comparison could be made between it and the standard finish as part of some night visibility experiments which were being carried out at Northolt.

Professor Mertons visit to the RAE seems to have taken place on the 19th April, following which, some agreement was evidently reached, as on the 25th April, Woodward Nutt forwarded to Dr Ramsbottom a sample of Professor Merton's dead black finish with the
expectation that not only would the RAE meet the standard that it set, but would be able to surpass it.

Whilst the RAE got down to work on producing the new finish, the Air Ministry informed the AOC Bomber Command that two suitable bombers were to be first sent to the RAE for treatment, and then in in co-operation with Fighter Command, they were to take part in the night visibility experiments taking place at the Air Fighting Development Establishment
at Northolt. By the 6th May, Bomber Command had decided that it would be convenient for one of the aircraft of 38 Sqn., currently attached to ADFE Northolt, to receive the experimental finish.

Throughout May, the RAE obtained and tested several proprietary black finishes from the paint trade as well as several finishes prepared on site. Finally a choice was made, and on the 6th June two Wellingtons were painted at Northolt. The first aircraft had the new experimental black finish applied to the whole of its undersurfaces and the vertical surfaces of
the fuselage, fin and rudder. At the same time a second Wellington received a similar scheme but using standard Night.
Experimental work at the RAE continued however, and by the 15th June a new 'Special Dead Black' had been produced which had greater light absorption than the experimental finish applied to the Wellington or the original sample provided by Professor Merton. A sample of 'Special Dead Black' apparently made from Nobels Monolite Fast Black was sent to Professor Merton on the 15 June. In his reply to the letter which accompanied the sample, Professor Merton expressed his opinion that the new sample gave a very successful and satisfactory result on which any improvement was doubtful.

By mid August, trials of this new finish were being organised, and had just started when the outbreak of war came on the 3rd September. The trials were swiftly completed and found to be successful. On the 25th September, the Air Ministry wrote to the RAE to ask them to forward as quickly as possible 1,000 gallons of Special Night to 3 MU for use by Bomber Command who were requesting that this material be adopted forthwith. Special Night was listed in 'AP 1086 the Vocabulary of Stores' under Stores ref 33B/ 299.

Both Service users and the aircraft manufacturers experienced difficulties in applying Special Night.

The Service found that following application on top of an existing finish the Special Night would crack and peel away after only a very short time. The worst problems seemed to lie in
trying to apply it to metal as it was found that it adhered to the fabric parts of the Wellington much more readily than to the metal parts. The aircraft manufacturers found that upon
application to the aircraft, the Special Night attacked the primer and both finishes peeled off in big flakes.

Following an RAE investigation of the problems being encountered with Special Night it was decided that the answer lay in revising the chemical formula using a more volatile chemical base. By the end of September 1940, the formula had been revised to contain Ethyl Cellulose and the nomenclature of the specification for Special Night was changed from RDM2 to RDM2A. The new specification Special Night RDM2A was included in AP 1086 in the Vocabulary of Stores as 33B/375, Its thinners were 33B/340, Whilst this appears to have made the paint more likely to adhere to the aircraft initially, irrespective of who applied it
or how, Special Night quickly gained a reputation for being easily removed from the aircraft by the simple act of touching it by hand.

On 28 November 1940, the MAP made it known that the surfaces of aircraft which were to have the Special Night finish should be first treated with a coat of Night in order to save a coat of Special Night due to the shortage of the pigment required in the production of Special Night. It was found that the Night under coat helped adhesion of the Special Night and so

The second problem with Special Night was its effect on performance.

On 27th January 1942, de Havillands wrote to the Directorate of Technical Development (DTD) at the AM to pass on results of a test that had been carried out on a Mosquito. De Havillands had carried out careful speed tests on one aircraft, W4082, to determine if the application Special Night any effect on the aircraft's performance. What de Havilland apparently did was measure the speed reached when flown in the Night undercoat, then apply Special Night and repeat the test.

What they found was that when flown in Night undercoat, W4082 reached a true airspeed 378 mph at an altitude of 22,000 feet and a weight of 17,000 lbs, whilst only a speed of 352 mph could be achieved when finished in Special Night. A loss of 26 mph.

When in formed of the the Controller of Research and Development (CRD), found this speed loss to 'staggering' and immediately asked the DTD check de Havilland's findings stating that if this was indeed the case, he wished the Air Staff to immaculately made aware of the situation and asking if they really required a matt finish for night fighters operating over the UK. CRD's option was that searchlight control had improved to the point where it was questionable whether the Air Staff would be correct in insisting that on the continued use of Special Night in view of the speed penalty incurred, and suggested that Night or Dark Green would be suitable instead.

Action was swift. Without waiting for the results of de Havillands findings to be confirmed the Directorate of Operational Requirements had contacted Fighter Command and appraised them of the situation. By 5th February C-in-C Fighter Command had agreed that the finish should intermediately changed to what documents dealing with this matter refer toas 'smooth black' or 'smooth night' finish.

On the 7th March the DTD wrote to the RAE with the opinion that the excessive roughness of the Special Night finish which had led to the dramatic loss in performance might be due to poor spraying technique. The DTD felt it was important to find out if this was the case, possibly in the light of later developments, Special Night was used widely by Bomber Command. The RAE was asked to investigate.

On the 14th March representatives of the RAE visited de Havillands where they were able to inspect W4076. They found the Mosquito to have a a surface finish considerably rougher than it should have been and considered that this was due to the dope having partially dried before reaching the surface. The correct spraying technique was then demonstrated by the RAE representatives which involved flooding the surface with liquid paint which resulted in a much smoother finish.


On 11th October, 1942, in accordance with Memo CS 13263 orders were issued to Bomber Command stating that Night DTD 308 was to be used in lieu of Special Night RDM2A for the undersurfaces of all aircraft currently in production and those already in service were to be repainted as operational commitments allowed. There was inevitable confusion between RDM2A' Special Night and Night to DTD 308 finishes, and in order to correct this a further
order was promulgated to the effect that from the19th October, 1942, Night DTD 308 was now to be referred to as Smooth Night and was to replace Special Night Finish on all types in production.



ln the UK, experiments with night camouflage finishes carried out during the 1930s had focused on developing a black paint which was sufficiently matt to absorb any light shining upon it. In the USA, unlike in the UK, when such finishes were found to be unsatisfactory,
trials were carried out with smoother paints. This led to a dull but smooth black finish,
Bulletin 41 No 44 being adopted for the P-70 in October 1st 1941 .

The Office of Scientific Research's camouflage section, which was located at Massachusetts Institute of Technology, suggested that a very smooth and highly glossy black finish would be even more effective as it would reflect the light away from any observer who was not observing the aircraft at exactly the correct angle (referred to as the 'specular angle') to see the reflected light. (In simple terms it is the light that is scattered or dispersed that makes the aircraft visible. By reducing the amount if scattered light the aircraft is much harder to see.)

Trials with such a finish were apparently put in hand at Eglin Field during the summer of 1943
which led to Eglin Field report No 3-43-1 14 'Test of glossy paint for Night camouflage' being published on 10th December 1943. This stated that comparable tests conducted at Eglin Field with aircraft finished with a special black paint of high specular and low diffuse reflectance and an aircraft finished with the standard matt black paint had been carried out. The matt black aircraft appeared 'silvery' white in searchlights whilst the glossy black aircraft was invisible 75 percent of the time and the effectiveness of both optically and radar controlled
searchlights was greatly reduced except at the specular angle. Eglin Field recommended that the special black paint be standardised and replace the standard matt black.

Following the submission of this report, US Material Command initiated the use of Gloss Black camouflage paint on 12 January 1944. It requested that all night fighter aircraft in production, the P-61 and P-70, be camouflaged with gloss black paint. This order superseded all previous orders for the camouflage of Night Fighters.

The Engineering Division at Wright Field assigned this new gloss black paint the ANA
designation No 622 and named it 'Jet'. On 15th March 1944 they had stated that it would be added to the list of standard aircraft camouflage colours listed in ANA Bulletin No. 157 as soon as possible. This however did not take place until the issue of ANA Bulletin No. 157b on 20th August 1946, about a year after the end of the war.

A quantity of the paint was made available to the British to carry out trials. ICI carried out experiments to manufacture the finish using pigment supplied from the USA which was very finely ground. Trials were carried out of a number of Halifax IIIs.

The findings of the trial were set out in RAE Report No. Ch. 4.10 dated May 1944. The report
concluded that the glossy camouflage made it appreciably more difficult for the searchlights to
find their target and there was some evidence to suggest that it also made it more difficult for the target to be held. ln general the glossy finish increased the difficulty of seeing the illuminated target from the ground, the effect being increased with distance. At close range, however, the target was more easily seen. The glossy camouflage was found to interfere with recognition by giving less uniform definition with confusing highlights.

Great care was necessary in avoiding scratches on this finish and in removal of dirt, oil etc. Affected areas were to be touched up as soon as possible to maintain the smooth glossy finish which was an essential requirement.

The materials were stated to be Special Glossy Black (Synthetic) - 1 gallon Stores reference
33B/642 (lCl number 27-100261 and its special thinners stores ref 33B/643 (lCl number 149-585) for half a gallon for metal surfaces and Special Glossy Black (Nitro Cellulose) 33B/644 (lCl number 212- 1160) and its thinners 33B/645 (lCl number 327- 348) for fabric surfaces.

Accumulation of dirt was not to be removed in any circumstances by dry rubbing but with soap and water liberally applied with rags. With careful attention in this respect, it was estimated that the finish would maintain its properties for about six months. The finish was never to be polished as even wax polishing had proved to be detrimental causing an increase in diffuse reflection. It was preferable to apply the finish direct onto bare metal after it had been degreased, but where it was necessary to apply it over a component already treated with primer or painted, at least two coats of the glossy black would be necessary On
bare metal, one coat should be sufficient. When touching up, the previous finish was to be well rubbed down with dry carborundum paper (Stores ref.33C/648) and all dust removed before application of the paint. Any painting or touching up of this finish should be carried out in a hangar away from any further dust which might collect on the drying paint. Absolute cleanliness was essential at all times.

Post war, the finish was adopted as Anti Searchlight Glossy Black.

AC/DC - Back in (Anti Searchlight Glossy) Black - YouTube

www.youtube.com/watch?v=pAgnJDJN4VA

It's good to read a report that gets Woodward Nutt and Ramsbottom together.

Good tunes too.