Just received a call from a customer that ruined 3 pairs of his favorite pants w/ bleach. The fabric is thin wale corduroy. Thier original colors were black or navy. How difficult is it to overdye this type of a garment? I have limited experience using black. My concern is the difficulty in achieving an intense enough color. Also, will the bleached area reaact to the dye differently than the non bleached. Would I need to strip the pants of all color before applying the black dye? This is not a job I would normally take, but thought I'd look into to to learn something new!