How do I feed dry leather on antique boxes?

A high-quality microcrystalline wax provides the safest treatment for dry hides. Apply a very thin coat with a soft cloth and leave it to harden for an hour. Buff the surface gently with a clean duster. Avoid liquid oils and saddlery dressings. These can soak through the thin skin and dissolve the historic animal glue holding it to the carcase.

What is the best way to clean interior velvet?

Brush the pile gently with a soft, dry clothes brush. This lifts the surface dust without driving dirt deeper into the fabric. Avoid liquid upholstery cleaners. Moisture ruins historic velvet and warps the thin wooden tray beneath.

I recently inherited a large leather covered document box from my grandfather but the brass lock is stuck shut and I have lost the original key. How can I safely open it?

Take it to a traditional locksmith. Many high street key cutters lack the tools needed to pick early lever locks without causing internal damage. Do not pry the lid. Forcing it with a screwdriver will snap the brass catch or splinter the wooden carcase. An experienced specialist can pick the mechanism. They will often cut a sympathetic replacement key from a period blank.

My writing slope has several deep scratches on the top surface where the raw wood is showing through the hide. Should I try to stain the wood dark to match?

Leave the raw wood exactly as it is. Those scratches tell the history of the object and blending them in rarely works well. Modern stains tend to bleed into the surrounding historic hide, creating dark rings that look worse than the original damage. A light application of clear wax over the whole lid will protect the exposed timber without altering its colour.