How to stick cork sheet to a cast iron surface

Cast iron is the awkward half. It is porous by metal standards, it usually carries oil, wax or a light rust bloom, and paint on old cast iron is often lead-based and poorly attached. Whatever you bond to is what the joint is attached to, so take the surface back to sound clean metal and degrease it properly.

Cork is the delicate half. It is compressible, absorbent and dimensionally unstable when it gets wet. Water based adhesives soak in, the cork swells, and as it dries it shrinks unevenly and lifts at the edges. A solvent or pressure sensitive spray puts a controlled thin film on the surface instead.

The reason for spraying both faces is the same as with any contact-type bond: what you are joining is adhesive to adhesive. Coat one face only and you get a fraction of the strength, and with a large sheet that shows up as bubbles and lifted corners within days.

Be realistic about the limits. Spray adhesive softens with heat and will not survive a hot surface, and cork on bare iron traps moisture against the metal. This is a good method for a dry interior job and a poor one for anything warm, damp or outside.

1. Take the cast iron back to sound bare metal: wire brush any rust, and remove flaking paint.
2. Degrease the metal thoroughly with isopropyl alcohol and let it flash off. Do not touch it afterwards.
3. Cut the cork sheet slightly oversize so you can trim it flush later.
4. Mask around the area. Spray adhesive drifts further than you expect.
5. Spray an even coat onto the metal and onto the back of the cork, holding the can about 200mm away and keeping it moving.
6. Wait until both faces are tacky rather than wet, usually 2 to 5 minutes depending on the product.
7. Lay the cork down from one edge, rolling it into place so no air is trapped, then work it over with a roller.
8. Trim the edges flush with a sharp blade and leave it an hour before use.