This topic is quite timely for I just today, finished the last coat of bottom paint after completing the barrier coat process. Fourteen years ago, I stripped the paint off, ground out jelly bean-sized blisters and applied the Interlux barrier coats. Two years ago when I hauled last, I noticed a few blisters showing and decided that it was time again. I hauled early last fall, actually paid someone this time to strip the paint down to the last barrier coat which cost me $1000 to sand it down. It was a major job since the early coats of bottom paint were Trinidad which is very hard and gums up the sand paper quickly. I ground out the blisters myself with a rasp bit on my cordless drill. Let dry, let dry, let dry.....
I followed the directions from Interlux for filling the ground out blisters and then started the barrier coat process again. I teach high school and this past week was my spring break and it took all of this week working very hard, about ten hour days, to do the whole process including waxing the topsides and painting the boot stripe, but it is done and I hope not to repeat it for at least another 14 years! I bought 4 gallons of the Interlux 2000 and two gallons of the bottom paint all added up to about $700 from Defender....West Marine priced out at $1200 !!! Yes it does get pricey to keep those pesky blisters in check
I am trying the new Petit Ultima Eco paint this year, so I guess I am a guinnea pig since this is a new paint...we'll see.