I tried the do it-yourself method with the spray kit and it lasted about three months. I now need to try it again and believe there is three ways to upgrade my tub. 1. Simply a new tub installed and the re-tile as needed. Costly but best. 2. A tub "jacket" installed over the old tub. costly, reduces size of tub and reported problems with these systems. 3. A profession chemical spray in treatment. Don't know the cost but suspect several hundred dollars. Would like to hear you thoughts, recommendations, etc. on the way to go. I plan on selling the house and cost is a factor, but also don't want to stick it to the new owner. Thanks for information you send my way.