Lettering on metals - how is is done?

[ScottBouch]

Hi all,

With vintage (circa 60's) avionics and other high quality equipment, lettering / markings often appear applied neatly direct to metal chassis, commonly on anodised aluminium.

Example here from within a C1607 (PTR-175) radio controller:
http://www.scottbouch.com/ptr175-con...-inside-01.jpg

And here from within an A1961 amplifier:
http://www.scottbouch.com/amplifier-...61-9668-02.jpg

The lettering appears like paint stencilled on, but can't be surely as it'd take forever...?

Is it a form of Letraset dry rub-down instant lettering? If so, was there a method to make your own straight strings of Letraset instead of having to rub individual characters one at a time (and getting them all wonky)?

These days it's all about printed vinyl stickers, even punched Dymo labels are old hat now... but if you're restoring a vintage project, it'd be good to have the markings in keeping with the original looks of it.

Cheers, Scott

[MrBungle]

When I worked at a defence contractor years ago I replaced what they were doing with stick on labels from a label printer. Prior to this they were using high quality rubber stamps and a type of paint from what I could see. The stamps were modular so you could slide in different symbols similar to old "movable type" typesetters. They let them dry then went over the top with a brush and some varnish I think.

[ScottBouch]

Hi MrBungle, thank you!

That makes perfect sense, and would give the impression of being pained-on in the non-stencily way I was trying to describe.. Many thanks!

I wonder if any stamps still exist, or if there are matching equivalents available? Do you recall what the rubber stamps were known as, a trade name perhaps?

The nearest I can find as a modern equivalent after two minutes searching: http://www.ebay.co.uk/itm/Garage-Mec...-/141633451762

It'd be nice to find out more about the original Typeface / Font as the modern ones I've just found have narrower looking letters, and would still look a bit out of place on 60's gear.

Thank you, Scott.

[emeritus]

AFAIR, silk screen printing was used in production runs when I was at Plessey in the 1970's. In the lab we sometimes used Letraset on our prototypes when we wanted something better-looking than Dymo. One engineer found that his wife's clear nail varnish was more convenient for protecting Letraset than the official varnish we could get from the stores: nail varnish is quick-drying, very hard-wearing, and using its built-in applicator brush avoids the hassle of cleaning brushes afterwards.

[stevehertz]

At Thorn EMI Electronics where I worked, any 'extra' lettering on admiralty equipment, such as on sub units, rear and side panels etc, was normally hand inked by very proficient 'marker up' ladies who then applied a streak of conformal coating (varnish) over the top of it. The main legends on front panels would generally be engraved, or bolted on, engraved Traffolyte panels. And the equipments were always painted in that light admiralty grey 381 697 (pale blue) colour as specified by the admiralty.

[jamesinnewcastl]

Hi

When I were a lad... we had the John Bull Printing Outfit. A pic of John Bull on the front and inside a red plastic 'stamp' with 4 empty rows that would take squidgy rubber letter blocks - exactly the same as standard printing really.

Using a pair of tweezers and sticking your tongue out you could either get the next letter in or have it ping across the table...

Anyway I had never thought about using paint instead of the inked pad, possibly an etching paint if such a thing existed? The problem with the stamp was that you couldn't quite tell where the text would end up on the page so making lots of lined up text was beyond my 8 year old self!

Just Googled it and you can still get something like it.... or the real thing...


Cheers
James

[camallison]

Over the decades, my company produced equipment for ships engine rooms and bridge controls. For those we had anodised front panels and silk screened epoxy-based paint for lettering. Recently, I saw one that had been installed in the early 70s, and the lettering was almost as good as new. To the touch, the lettering feels ever so slightly raised.

Colin

[ScottBouch]

Thanks guys,

Having learnt from you, I imagine the front plate of this amplifier would have probably been silk screen printed then as part of a production run; white paint on black:

http://www.scottbouch.com/amplifier-...-9668-01-b.jpg


And inside the amplifier we see some NATO stock numbers hand painted on to transformers, and an Air Ministry stored ref number painted onto a relay:

http://www.scottbouch.com/amplifier-...61-9668-12.jpg

( My page on this amplifier: http://www.scottbouch.com/a1961-intercom-amplifier.html )

Thanks, Scott

[ScottBouch]

Hi Colin,

Thanks, yes some of this painted text lasts years looking as good as new, and yes, I know the "raised" feel you mention.

[ScottBouch]

Thanks guys for all the input so far; being born a generation too late, this is a field I'm a bit out of my depth with, but learning lots about bygone practices!

Thanks, Scott.

[McMurdo]

One of my jobs as a trainee was to print numbers on potted modules. We also used something similar to a john bull printing outfit, with special stamps (known as pads) for the logo and a thumbwheel-style stamp for the type number. The whole lot fitted into a heavy aluminium and steel press that was operated by a big handle that automatically inked the type and then pressed it onto the item in one go. There was a small jig that kept the item to be printed steady and in a consistent position.

Every so often we would have to squirt ink onto the inking platen from a toothpaste-type tube. It came in any colour and was rather sticky. It had to be cleaned-down with 1.1.1 trichloroethane.

The machine is called a pad-printer and they are often used for adding corporate logos or lettering to stuff that's been bought elsewhere, such as 'property of NHS' , promotional items etc.

Giant automated versions are used for printing decoration onto flatware (plates and saucers) here in the potteries.

[ScottBouch]

Thanks Kevin, I just googled "Pad Printer" and found a brand "TOSH" which made me smile!

Most of the ones I just saw online are big automated production line machines.

Thanks again, Scott.

[jamesinnewcastl]

Hmm, JB printing and Epoxy Based paint - now there's a thought - not much choice of font though...

I've been looking up pantographs to engrave and ink fill - just need to fit the trusty Dremel 6000 into it...

James

[russell_w_b]

Originally Posted by jamesinnewcastl

When I were a lad... we had the John Bull Printing Outfit. A pic of John Bull on the front and inside a red plastic 'stamp' with 4 empty rows that would take squidgy rubber letter blocks - exactly the same as standard printing really.

Likewise... A couple of years ago I bought some stamp kits from Aldi that came with the same tray of letters as a 'John Bull', a set of little tweezers, and a generous, self-inking stamper. I bought two, 'just in case' and they weren't that expensive: a fiver or so.

OK on a light-coloured surface with a thin layer of varnish on top, maybe?

[crackle]

I have recently experimented ironing on a laser printed layout to sheet metal for a power supply I am making, it can work very well, and I feel sure it could work just as well with lettering.
Print your lettering in mirror form, tape the paper with the lettering onto the metal face down. Then wipe over the back of the paper with a cloth wetted with white spirit.
Get the wife's best iron out on full heat and press onto the back of the area where the printing is. (white spirit and heat may melt the tape so make sure you keep the heat away from the tape.)
The result can be very good, you can get almost all the laser toner to leave the paper and adhere to the metal and you can actually feel the thickness of the print standing proud when you run your finger over it, and it does not rub off even when scratched with finger nail.
Some experimentation may be needed but It is something I will try again instead of using letraset, or stuck on labels.

I saw the process on Blue Peter years back being demonstrated by Valerie Singleton when they made some DIY printed T shirts.
The fainter lines around the transformer were my first attempt, but the final transformers footprint was smaller than planned.

I have been informed you can make printed circuits with this sort of masking.

Mike

[McMurdo]

I once made a lovely panel (in my eyes) for a power supply and marked it up with letraset (or whsmith version) and then gave it a spray with lacquer to protect it. The lacquer dissolved the letraset and it all ran in streaks looking like the front cover of a horror novel.

Oh, the pad printer we used was made by US company Markem who still make bar code printers and best-before-date print machinery.

[G6Tanuki]

You can actually get special "T-shirt-printing" laser-printer film that's designed to do the print-in-reverse-then-iron-on thing. Unlike paper, it';s designed so the ink only sticks very loosely [rather than penetrating into the surface] so you get maximum ink-transfer when subsequently ironed.

[I have memories of doing the same thing decades back using a H-P 7475A flatbed -plotter and overhead-transparency film]

[Oldcodger]

I've just posted on Homebrew about some Acetate sheets I found today in HOBBYCRAFT SHOPS. The laser ones are £3 per pack of ten and were said to be heatproof , possibly enough to iron a transfer. I use a PCB program called EXPRESS PCB. and it's possible to print in reverse ( using the PCB bottom layer ) -so I'd throw in the idea for anyone to consider.
Use Express PCB in PCB MODE to print the labels ( using the lower green PCB layer) and print onto a Laser sheet of acetate( with a laser printer ). This will give the label in reverse. Then iron on the laser print to the surface.
I do remember many years ago some form of kit for making labels based on a similar idea to the process of negative resist for the production of PCB. I mention it as it might jog memories of anyone who used it .

[ScottBouch]

Hi Mike that looks brilliant! Who'd have thought it! G6Tanuki has added to it with the "proper" stuff.

I like the idea of creating the source by computer and then transferring it to the metalwork, as it keeps everything neatly aligned... Only issue is finding a suitable font for 1960's engineering.. Arial looks wrong when used this way. Attached is another example (from the T5 Lightning aircraft painting guide) of the typeface of the era that I'm struggling to find a suitable modern alternative for.

Kevin - your horror movie description gave me a good mental image of it! Thanks!

This is great that more and more ideas / methods and techniques keep on being added into the melting pot!

Cheers, Scott

[MrBungle]

If you want a suitable modern font for equipment look for Futura. That was used by Tektronix in their equipment and manuals of the era and looks just about spot on. Use lots of all caps for headlines and keep copy short and sweet. My personal limited company branding uses it and has a 1960s Cold War feel to it. I think i spent more time obsessing about this than I did on setting the rest of the company up!