It's called Re-Glazing. It lasts 30 days to 2.5 years on average. It costs $200 to $450 ea. time. Yo might want to check out www.bathfitter.com and put an acryllic tub right over top of that one. It'll last 20 plus years and is the easiest to clean. It keeps your water warmer 30%-40% longer and can be done 3-4 hours.