Gillette Safety Razor

A double-edge blade out of its holder is razor-sharp on both long edges and almost invisible edge-on. Handle only by the short ends, and dispose of used blades in a sealed tin, never loose in a bin.

Gillette claims the combination — a thin flexible blade PLUS a holder that supports and curves it. Neither half is novel alone; the patent is about them working together.

Unscrew the handle and separate cap, blade and base plate. Three parts and one screw — the architecture has barely changed in a hundred and twenty years.

Blade exposure is how far the edge stands proud of the line between guard and cap. Blade gap is the space between blade and guard. These two dictate how aggressive the razor is — nothing else does.

Tightening the handle bends the flat blade over the cap's curve. That flex is deliberate: it tensions the wafer so it behaves like a rigid edge without being thick.

Saw two blanks to match the blade's footprint. Brass is right for a first attempt — it files predictably and does not rust while you are still fitting parts.

Work a gentle convex curve across the cap's underside. A flat cap leaves the blade slack and the razor chatters across the skin.

File a comb of shallow teeth along the leading edge. The guard is what makes it a SAFETY razor — it holds the skin taut and limits how much can present itself to the edge.

Match the holes in a standard double-edge blade so cap, blade and plate stack in register. Misalignment here shows up as one edge shaving and the other not.

Make the handle long enough to balance the head and thread it to draw the cap down onto the plate. The clamping force is what sets your gap — build the adjustment in.

Lay a straightedge from guard to cap and check where the blade edge sits relative to it. Aim slightly NEGATIVE for a first razor — mild is forgiving, aggressive draws blood.

Draw the assembled razor across an inflated balloon at shaving angle. A correctly set head glides; one with too much exposure bursts it immediately.

With a straight razor the user chooses the angle. Here the cap and guard together define it — you simply rest both on the skin. That transfer of skill from wrist to geometry is the entire product.

Work out the cost per shave of a disposable wafer versus a stone, a strop and the time to learn both. The arithmetic is the reason the straight razor lost.

The patent. King Camp Gillette filed on 3 December 1901 and was granted US 775,134, "Razor", on 15 November 1904. The specification is unusually blunt about intent: the blade is to be "thrown away when dull" rather than resharpened. Gillette was a travelling salesman for a bottle-cap company, and his employer William Painter had given him the advice that made him rich — invent something people use once and throw away.

The hard part was metallurgy, not design. Gillette had the concept by 1895 and could not make it work for six years, because nobody believed a sheet of steel thin enough to be cheap could be hardened, sharpened and kept flat. Machinists at MIT told him it was impossible. William Nickerson, an MIT-trained engineer, solved the manufacturing — the process for hardening and grinding thin sheet steel at volume — and it is fair to say the razor is Gillette's idea and Nickerson's invention. First-year sales were 51 razors and 168 blades. The next year, 90,884 razors and 123,648 blades.

Exposure and gap are the whole engineering. Blade exposure — how far the edge stands beyond the guard-to-cap plane — controls how much blade meets skin; blade gap controls how much lather and stubble can pass. Increase either and the razor cuts faster and cuts you sooner. The cap's curve tensions the flexible wafer so it resists deflection without being thick. Modern adjustable razors simply let the user vary the gap; the geometry they are varying is Gillette's.

The razor-and-blades business model is misattributed. The famous story is that Gillette gave away handles to sell blades. He did not — during the patent term he sold razors at a high price and kept blade prices high too, because the patent excluded competitors anyway. Cheap handles and expensive blades only appeared AFTER the patent expired in 1921 and rivals flooded in. Economists still call it the "razor and blades" model, which is a good name for a strategy its namesake adopted late and reluctantly. Worth knowing before citing it as the founding example of anything.