We’re making a subway sign! No, I’m not talking about the sandwich shop.

This project was inspired by the vintage posters that used to adorn the walls of New York City subway stations. Each line on the poster would designate a different station to help guide your way. This one, however, is a gift for my father and has several of the locations he will be visiting on a trip in the near future. Let’s get started!

This project started off with a 12” x 18” piece of 16 gauge mild steel. You may also come across sheets like this in hardware store as “weldable steel”. Low alloy steel is key for a later step when we rust the piece, we don’t want any pesky alloying like chromium messing with our patina dreams.

Using a caliper, holes were marked in each corner of the steel. Measuring equal distance from each ledge allows for precise placement of the mounting holes. After giving swift whack with a hammer / punch all holes are marked and ready to drill.

Using a titanium coated bit and a healthy dollop of cutting oil, each of the mounting holes were drilled out. There were a couple of burrs that decided to hang around the perimeter of the hole, but a quick spin of a countersinking bit took care of that.

Since this sign is going to be hanging on a wall, rounding the edges was decided to prevent any nasty scratches to the hanging surface. The bench grinder was used to shape a radius into each corner. A file took care of the rough edges and the basic shape of the sign was complete.

In order to promote the black paint adhesion, 400 grit sandpaper was used to rough up the surface and remove as much oxide as possible. A wipe with a cloth and a bit of degreaser ensured that all that cutting oil from earlier was sufficiently removed.

The entire sign was coated in about 4 light coats of black spray paint. Generally, a primer would be recommended when painting metal, however we aren’t too concerned about surface finish as the sign is intended to look old and beaten like it has been hanging in a subway for the last 60 years. The paint used was Krylon Paint and Primer in One. 2 in 1 paints are great for projects like this as purposely removing the paint does not reveal any grey primer beneath.

While the paint dried, I booted up the computer. Using sign-making software I drew up the vector text of all the location names. After a bit of fiddling around with sizing and text position I generated the plot path and sent it to the plotter. Once the vinyl was cut, the excess was removed and transfer tape was applied to apply the vinyl to the piece.

After the paint had dried some 2000 grit sandpaper was used to wet sand the entire surface. The wet sanding provides a smoother finish and removes any surface roughness, this is done so that the vinyl will adhere better. Any paint that has dried in the air will create a fine dust on the surface of the piece that will result in poor adhesion of the vinyl. After sufficiently cleaning the surface of any dust and contaminants the vinyl was applied.

Well I must say that looks pretty good. This project could stop at this point, but let’s subject this thing to years of misuse and abuse in just a few minutes.

Using some black and brown acrylic paints, the entire surface was dry brushed and speckled with paint. Special attention was paid to getting the paint onto all the edges of the letters. This is just a preliminary dirtying, the real magic comes next.

Using a couple of wire brushes the entire piece was scuffed and scratched. Certain area received a more rigorous scrubbing to remove the paint down to the bare metal. The edges were given special attention as they are naturally most likely to be worn down over the years. Now that the sign looks sufficiently beaten, it’s time to artificially age it using SCIENCE!

PLEASE NOTE! PROPER SAFETY EQUIPMENT IS A MUST!

This next step involves the use of muriatic acid and hydrogen peroxide. Muriatic acid is a dangerous and volatile compound and must be used with utmost caution. At this step I have acid-proof gloves on, am using eye protection and a 3M respirator with 6002 acid vapor cartridges. I cannot stress the importance of safety enough when dealing with these materials. For home projects I recommend using vinegar (acetic acid) instead of the much more potent muriatic acid. To cause the metal to rust, the hydrogen peroxide was applied to all the bare metal surfaces. The muriatic acid was then diluted to about 10% by volume and sprayed onto the surface after about 25 seconds. The combination of these chemicals cause for the very quick formation of iron oxide. However the iron oxide is formed in a solution – the piece could be left to dry naturally, but we want this to rust even faster!

A small butane torch was used to accelerate the reaction and evaporate the water. The concentration of the chemicals becomes greater as the water evaporates away and heat also helps accelerate the chemical process. The metal turned a beautiful array of rusty hues in just a few seconds. After all the rust had formed and the piece was dry, the torch was used to burn a few vinyl letters to add a little extra age.

A file and a couple of wire brushed were then used to beat up the edges a bit more, lending the appearance of more recent damage. Once I thought that the sign had been aged enough I dropped it on the ground, just for good measure.

Well there we have it. A vintage looking subway sign with real rust. This was a bit of an experiment with the acid method. There is a wide array of techniques usable for creating surfaces that look rusted, however if steel is being used as a base material there is no excuse for just making the real thing. This technique is great for pieces that are going to be hanging on a wall but I don’t recommend handling rust as it dusts off and is structurally much weaker, alternative techniques are preferred for props and armor.

Signing off,