A. Does your sofa’s original color need some stripping out? It could probably be that your new color is paler, faded, or has a different tone. Remember also that preparation can provide successful results and this can be applied as well when decorating your home. If you apply the dye to your sofa cover with uneven and faded baser color, the color will still be visible.
Refrain from using chlorine bleach because this will cause damage to your fabric. Always use the dye-stripping agents recommended by dye suppliers. The printed fabrics will seldom strip. Patterns will still be visible in all but the colors with the darkest tones.
B. Doing the stripping process before dyeing can help the washing process in trying to remove anything that may be found in the sofa surface that might interfere while the process of dyeing is done or might still show or appear after the dyeing process.