Martexin Original Wax
Reproof the old fashioned way. If you ride rain or shine, your canvas bag will appreciate an occasional touch-up or re-application of wax. You probably already proof your Brooks saddle; canvas also needs a little preventive maintenance for best performance.
It's also great for waxing previously unwaxed canvas. Just test in an inconspicuous spot first to see if the result is to your liking.
1.5 oz. tin is enough to treat a larger sized bag.
(Please note that wax should not be applied to leather, binding/edging trim or synthetic fabrics. Warm up wax, apply sparingly and finish off with a hair dryer. Do not overheat.)