Not sure what material are your buckets. My lady Clo used wood stain on our white wicker chairs. They look great

You will first need to strip off the existing paint....use wood stripper. apply by brush. follow the instructions and exercise safety first. use a paint scrapper lightly to remove the majority of the paint. use lacquer thinner and steel wool...0 or 00 will do. then wipe it down again with a rag and lacquer thinner...this is to ensure its clean of stripper and contaminants. then your left with raw wood...do what you will after that...good luck and send me a pic when your finished...I would like to see...have fun!!!