I think a little more information is required. Is the case British is it a soft Canvas gun slip type or is it a Canvas over a wood box case, Is it a Vintage B4 1900 or 1930's on wards. B4 1900 a lot of the Canvas used was made from Linen thread. Buckram, Calico, are 100% cotton and today mixed fiber calico or the heavier canvas is now more common than the pure cotton type. A problem I found on this side of the pond is that heavy canvas and the lighter weight calico their colour range is limited. the last bolt of Calico I purchased I could only get in white and dye it my self with a varying outcome. Wax works on canvas but it has a lot of not so good side effects can stay sticky hardening the weave darkening the colour, I prefer clothing waterproofing spray it stops staining colour change and keeps the water out.Though I do wear a waxed jacket to keep the Brit wet weather out but the wax it is treated with is a mix and does not dry otherwise the crease lines in the fabric would eventually break.
