Canvas is forgiving, which is why it has been used for work bags for a century. It is not indestructible, and the things that ruin a canvas bag are usually the things people do trying to clean it.
Start with spot cleaning
Most marks come off with a damp cloth and a little mild soap, worked gently and then blotted rather than rubbed hard. Do this when the mark is fresh. Canvas takes a stain far more readily once it has had a week to settle.
Hand wash if it needs more
For anything a cloth will not shift, hand wash in cool water. Do not wring the bag out. Press the water out and let it dry naturally, away from direct sun and away from radiators. Heat is what makes cotton shrink unevenly and what makes a structured bag lose its shape.
Reshape the bag while it is still damp so it dries in the form you want.
We have not tested machine washing
Our care line says spot clean or hand wash, and that is the whole claim. Our bags have foam and a board built into them, and we have not run finished production stock through a machine to see what happens. Until we have, we are not going to tell you it is fine.
The same goes for water resistance. We make no claim, because nothing has been tested.
Hardware and shape
Antique brass hardware will dull slightly with handling. That is the finish behaving normally, not a fault. Leave it alone rather than polishing it with anything abrasive.
When you are not using the bag, store it upright with something soft inside to hold the shape. Hanging a structured tote by its handles for months will stretch the webbing where it is stitched.