Wireless Set No. 52 Canadian - Project

[David Dunlop]

This last weekend I finally found the BNC Cable I had been looking for and as I suspected, it was a perfect match for the one required for this Wattmeter and it is now stored inside the cover of the meter, along with the Probe.

David

[David Dunlop]

I have completed a round of stencil tests with the brushes I recently purchased. I did not try the 3/4-inch brush as it was far too large for the size of stencil I am using.

The first attempt was the letter 'N' lower centre in the photo with the 1/2-inch brush. Way too much bleed under the stencil on its own so I stopped with the one letter. the next attempt was the test block to the right side with the 3/8-inch brush and the plain stencil. Cleaner, but still way too much paint bleed under the stencil. Both of these tests were done with multiple thin coats build up with the brush.

The last test was the block to the left. For this, I secured the stencil to the test folder with a coat of Rubber cement, pressed the stencil down with a pencil eraser to ensure the stencil was as flat as possible and I let the rubber cement dry for 20 minutes at room temperature. I then rubbed the excess cement off the top of the stencil with my finger and used a round toothpick to clean up any excess cement inside each stencil segment. Then out came the 3/8-inch stencil brush again and multiple coats were build up until the majority of the folder colour vanished.

A very slight bit of paint wicking took place, but overall, I am very pleased with this result and kit will be the process I use with the tool box stencil.

David

[Bruce Parker (RIP)]

There must be an easier way. The factory would have been pumping these out by the hundreds and wouldn't have fought as you are fighting. What was their secret? Any chance they were screened on?

Originally Posted by David Dunlop

I have completed a round of stencil tests with the brushes I recently purchased. I did not try the 3/4-inch brush as it was far too large for the size of stencil I am using.

The first attempt was the letter 'N' lower centre in the photo with the 1/2-inch brush. Way too much bleed under the stencil on its own so I stopped with the one letter. the next attempt was the test block to the right side with the 3/8-inch brush and the plain stencil. Cleaner, but still way too much paint bleed under the stencil. Both of these tests were done with multiple thin coats build up with the brush.

The last test was the block to the left. For this, I secured the stencil to the test folder with a coat of Rubber cement, pressed the stencil down with a pencil eraser to ensure the stencil was as flat as possible and I let the rubber cement dry for 20 minutes at room temperature. I then rubbed the excess cement off the top of the stencil with my finger and used a round toothpick to clean up any excess cement inside each stencil segment. Then out came the 3/8-inch stencil brush again and multiple coats were build up until the majority of the folder colour vanished.

A very slight bit of paint wicking took place, but overall, I am very pleased with this result and kit will be the process I use with the tool box stencil.

David

[David Dunlop]

Hello Bruce.

When I was in Junior High School, the Father of one of my friends was an Illustrator who owned a sign shop. He had a lot of silk screen equipment in their basement, and I wish I had paid closer attention to it all at the time.

I do remember the screens were a two part item consisting of the thin fabric screen and a mask bonded to one side somehow. You cut the design through the mask and peeled away the bits you wanted the paint to pass through. The huge advantage of this printing technique is the design and any characters therein can be solid and continuous. By comparison, a stencil requires webs in the characters to hold them together. It would absolutely be possible to cut a silk screen mask that looked exactly like a stencil, but why?

Screening was definitely used with wireless equipment during the war. You can see it on any 19-Set Spare Parts Box, or Spare Valve Box, and if it is minty enough, you can often see the fabric shadow in the white paint under a low angle light.

Looking on the web today, there are a few commercial, line production stencilling machines available, but most seem geared to working with electronic circuit boards and other small, thin items of that nature. It is entirely possible these modern, compact machines evolved from much larger equipment from decades ago. We may never know.

Regarding the various boxes/cases for the 52-Set, I have photos of two different tool boxes with original markings, one in Canada and the other in England. The stencil markings on both are spot on identical in both form and location on the two boxes. I also have on hand, two Spare Parts Boxes and again, the stencil marking shadows are spot on identical in form and location.

In the pre-computer era, Sign Painters and Illustrators, were highly skilled positions and there was probably a lot of cross reference to other closely related skills like screening, stencil making and even engraving…all hand done. These physical skills are largely lost today. The station on the line for stencilling these boxes/cases was probably occupied by a lot more than just one person to keep production numbers up as you have noted. It would not surprise me at all if each work table was set up with jig options to hold the various cases/boxes in a specific spot, and perhaps even some form of mechanical arm which could swing the stencil down to the same spot for each type of case/box being worked on.

The viscosity of the paint is also critical. Too thin and it will wick under the stencils in a heartbeat. Too thick and it becomes hard to apply and you risk it drying out. Just right, and a skilled worker, and away you go!

Sorry for the length of this reply, Bruce. It amazes me what the older generations were able to accomplish with pure mind power and great hand/eye coordination and as much as I would love to know how they accomplished things like applying these markings, an answer may never be found. In the meantime, I shall muddle along and try and honour their collective skills as best I can. That probably means I end up drinking more than any of these workers ever did, but that is not a complaint…

David

[Bob Carriere]

.....works good BUT will leave permanent mark on flat OD paint like truck doors. A stencil cut on 15mil acetate held in place with magnetic strips works well with very thick stencil paint and foam dabber.

Flat OD paint will mark very easily and cannot be repaired short of repainting the whole door skin... trying to re-spray patch always mess things up and stencil paint has to be re sanded to bare primer.

Cheers

[David Dunlop]

Bob raised a couple of interesting points last week regarding the use of stencils and to be on the safe side, I decided to double check both factors before proceeding further with work on the tool box.

The first potential problem was the use of rubber cement on flat paint, or even semi flat paints.

Years ago I restored a pair of M38 CDN’s and painted them both the original semigloss factory green. I was lucky at the time a company called Rondex here in Winnipeg, still had the original paint sample catalogs for Dulux paints and it covered all the Canadian Military Vehicle colours from the factory new M-Series back to 1944-45. When it came time to apply the CFR Numbers I used stencils mounted to the vehicle with rubber cement with no problem at all, but the paint in question was an enamel semi-gloss. Today, the term ‘semi-gloss’ seems to have disappeared from paint terminology, being replaced with names like ‘Eggshell’ or ‘Satin’, and most paints today are latex or other water-based variations.

So my first test last week was to coat a small piece of oil board with rubber cement and stick it to the bottom of the tool box, wait five minutes, peel it off, let the cement dry completely and rub it off to see what happens. As per the first three photos, the solvents for the rubber cement did not alter the finish on the satin latex paint at all. Good to know.

The second point Bob mentioned was the use of those small foam paint brushes to apply the stencil paint. Debbie happened to have quite a selection of these in her crafting supplies so I borrowed one of the small, black rectangular ones with the chisel tip to test it out.

The last photo shows the results of this test in the lower left corner after the stencil had been glued down with rubber cement and the excess cement cleaned off prior to painting. Directly above that test is the sample done with the 3/8-inch stencil brush on the same glued down oil board and off to the right the same brush on an unsecured oil board. After looking at the results for a bit, my quality ranking would be the top left result with the small stencil brush is best, followed pretty closely by the foam brush below it and a distant last place is the unsecured stencil and small brush to the right side.

I think the problem with the foam brush test is more a factor of the small size of the stencil cutouts, rather than the foam brush. With the narrow openings of the characters, too much of the foam is on top of the stencil and the foam has difficulty getting in close to the edges. As a result, the sections of some of the characters have varying widths to them. With the small stencil brush, some of the bristles clearly hit the face of the stencil, but not enough that they still flex and allow the other bristles to reach down inside the cut-outs and fill it more evenly with paint.

I think with larger sized stencils, a foam brush could easily hold its own with a bristle brush for stencil work.

So with that out of the way, and thanks again Bob for raising these points, the next step will be to apply the required stencil to the tool box.


David

[David Dunlop]

I applied the stencil to the tool box this morning and I personally think it is the worst bit of restoration work I have ever done!

The tool box was on its back on a thick towel on the bench and I applied a good amount of rubber cement to the stencil before correctly aligning it down on the front of the box. I then placed a heavy steel plate weight over the top and let it sit for half an hour at room temperature.

After removing the weight and carefully rubbing away all the rubber cement that had to go, to get a clean working surface, I started the slow stencil brushing process with the 3/8-inch stencil brush. I even held down suspected problem areas on a few characters with the head of a 4-inch common nail to be on the safe side and made sure the paint was built up of several thin layers, rather than one or two heavier coats.

After half an hour for the paint on the stencil to dry to the touch I carefully removed the stencil and cleaned it up. An hour pater I carefully rubbed off any dried excess rubber cement. Of 51 characters on the stencil, 20 require touch up work, and of those, six need it badly. I will worry about that next weekend to let the white stencil paint fully cure.

On the bright side, I have an entire winter looming ahead with lots of free indoor time available to tidy this up. I still have a package of large pink rubber pencil erasers left over from restoring the damaged original decals on the 52-Set Sender panel. They should work just as well for this task, along with the same set of ultra fine tip paint brushes.

I also took some time this morning to have a much closer look at the original stencil on my 4-Section Aerial Reel. There is not a trace of a brush mark anywhere on any of the letters, or any form of screening for that matter. What I did see, however, was an ever so slight ‘ghosting’ of paint along the bottom edges of the lower two lines of the stencil.

Bruce raised a good point the other day regarding the Stencil Station on the Production Line. They would be getting a lot of items through that station daily and it would be a bottleneck in no time working stencils by hand with any sized stencil brush, regardless of staff compliment. Canadian Marconi could certainly have used air guns at this station, but that seems like overkill. Air guns in paint work are at their best for large volumes of paint over large areas quickly and pack a fair bit of air pressure behind them. They would be wasting a lot of paint using them for stencils. Stencils are much more detail oriented. I don’t know why it never crossed my mind earlier, but perhaps this station on the line was using Air Brushes. Air brushing was a very common function in the photographic sector prior to the computer age and that spun into all sorts of publication work. Air brushes were also common for a lot of detailing in paint shops in many sectors. The Cabinetry Division at CMC probably had them on hand for fancy detail work and they operate well at pressures far lower than what is needed for a common air gun. With an air brush at a stencil station, an operator could easily master holding the stencil in a jig by hand and work an air brush at the right distance and correct paint load to get little or no under spray behind the stencils, and with that equipment you would have much greater throughput for the line.

Maybe I will dust off my Air Brush and try it out when I get to working on the Spare Parts Boxes and see how it works. Assuming senility does not take hold in the meantime.


David

[Bob Carriere]

Hi David

I would have concerns using any kind of air brush as it might lift the stencil ever so much.....

The stencils I have seen that were used repeatedly were made of cut out brass sheets and very rigid....... and they used a roller ( in Black) and the dabbing brush was a well worn caked short hair thing that had turned into a felt like glob of semi dried paint....... worked well on wooden crates going up North.

Crates had the lettering over painted white and reused.......

This was done in a wharehouse and in some cases the trucks were idling at the dock to be loaded.....

Your tool box is really well done........ not sure they would have been all done so neatly in a shipping department........ reminds me of all the highly visible spot welds done on CMP bodies..... if it was solid it got shipped.

Love to follow all your hard work!!!!

Cheers

[Jordan Baker]

See the following link for a few period photos of how markings could be applied.

http://www.questmasters.us/Restoration_Supplies.html

The 4 sections aerials reel looks to have been sprayed.

There is also what’s called rocker mount stamps. Once the stamp is made, the application goes very fast.

[Alex van de Wetering]

David,

Nicely done and thanks for sharing your experiences here!

I guess if you have trouble with the cardboard lifting from the surface due to the moisture from the paint or air flow from the paint gun...you could try thin plastic sheet or sticker material in stead. I presume the stencil should not have any trouble cutting this.

Originally Posted by Bob Carriere

Hi David
The stencils I have seen that were used repeatedly were made of cut out brass sheets and very rigid.......

I have a set of those....it has individual letters in brass with a small ridge along the edges, that allows you to, sort of, link multiple letters into words. Presemably mine are post-war Dutch or German army.


The website that Jordan posted gives some nice pictures of the different applying methods used in period.....and also shows why lettering on original items is not always properly centred, straight ....and sometimes with paint smudges. Something we try to avoid as restorers!
What I do always find annoying with these stencil suppliers is that they seem to spend no energy at all at getting the font right! This website even shows a comparison of first aid boxes and it clearly shows the text is the same, but the font is wrong.

If you are using pre-made original stencils, or a stencil machine like David is using, you'll find that the width of gaps in the material is usually equal, I mean the font is specifically designed for stencilling, avoiding narrow grooves where paint can't properly run through. Some of these custom stencil suppliers however use computer fonts which are designed for book print or even web-use, designed along different guidelines, for instance to make them easier to read. As most of these suppliers will sell you stencils cut in sticker material, which seems to work very good for applying markings on vehicles by the way......why not use the proper font in stead? The cutting plotter wouldn't mind!