Vitreous Enamel Advertising Signs: How They Were Made and How to Spot a Fake
A good enamel sign is one of the few vintage objects that can survive outdoors for sixty years and still look sharp. It is also one of the most widely reproduced. Telling the two apart gets easier once you understand how the real thing was made, so we will start there.
How a vitreous enamel sign was made
Vitreous enamel is powdered glass, called frit, fused onto metal by firing. A typical sign began as a sheet of steel, cleaned of oil and rust so the enamel could grip. The steel was coated with a ground coat of frit and fired, giving a hard, glassy base layer. A solid background colour followed, then the lettering and artwork, with each colour applied and fired in turn. Colours were laid so they overlapped slightly at the edges, which allowed for small misalignments between layers. That slight build-up where one colour meets another is often called shelving, and it is one of the best signs of the real process.
The result is a surface that is smooth, hard and slightly raised where colours meet, bonded to a steel core.
What the real thing looks like
- Weight. A genuine sign is heavy and rigid for its size. It will not flex.
- A glassy surface. Run a finger across a colour boundary and you can often feel the edge of the next layer.
- Chips that show layers. Where enamel has chipped away, you should see stepped layers of glass, usually down to bare steel. Wear tends to be uneven and concentrated where a sign was fixed, knocked or exposed.
- Dark, aged rust. Rust in a genuine chip is typically a dark brown or black, and it does not usually bleed across the face.
- A finished back. Many signs have a fired enamel or dark coating on the reverse, not bare bright steel or a coat of black paint.
- Magnetic. The steel core means a magnet should hold firmly.
The tells of a reproduction
- Printed rather than fired artwork. Look closely at the edges of letters. Sharp, clean edges with the odd tiny island of enamel suggest screen printed vitreous enamel. Fuzzy edges or a dot pattern point to modern printing.
- Chips in the wrong places. Faked wear is often evenly spread around the edges, and the chips are shallow, with no layered enamel visible in them.
- Bright orange rust. Artificial ageing often produces a fresh, orange rust that looks too even.
- Too light, too thin, or flexible. If you can bend a corner, it is not heavy gauge enamelled steel.
- Modern fixings. Holes that look freshly drilled, or a back with no enamel at all.
No single test is conclusive. Look at several together, and be wary when a sign looks too good for its supposed age or the price looks too low for the subject.
A piece we found: Roja Pakku
Our Roja Pakku sign is a vitreous enamel on steel advertisement for betel nut, made for N.V.K.M. & Sons of Dindigul in Tamil Nadu. It is bold cobalt blue and white, with Tamil script and a diamond trademark badge, and it carries a registered number, 118331. Enamel signs were made across the world, not only in Britain and America, and the South Asian examples have a graphic confidence that is hard to match. The registration number is exactly the sort of detail that helps with research, because it ties the design to a specific business and a specific period.
You can browse everything we have in the same vein in our signs collection.
Common questions
How do I clean a vitreous enamel sign?
Warm water, a drop of mild washing-up liquid and a soft cloth are enough. Avoid abrasives and solvents. Never polish over rust or chips, as you can lift loose enamel, and avoid retouching with paint, which hurts both the look and the value.
Can I hang one outside?
Enamel was designed for outdoor use, but chipped edges let moisture reach the steel, and rust spreads from there. If a sign has chips, an indoor wall or a sheltered spot will keep it as it is.
Does a chip lower the value?
Some wear is expected and often welcomed, as it shows honest age. Large losses across the lettering or face matter more than edge chips around the fixing holes.
If you are unsure about a sign you own or are thinking of buying, send us photos of the front, back and a close-up of any chips through the contact page and we will tell you what we see.