Retro clean is a product to wash antique fabric with to clean and brighten. It can work wonders but your blocks may not be colourfast. To tell if they are going to bleed, dampen a Qtip and rub the coloured fabric with the Qtip in an inconspicuous spot. If any colour transfers to the Qtip you have a bleeder and it is best to never wash them. If you can’t wash them, there isn’t much point to make them into a quilt. You could make them into a wall hanging that could be vacuumed or put some blocks in shadow boxes for family members.