Blister Photo & Question

[Ironhorse74]

Originally Posted by minaret

Personally I believe recurring blisters are often the result of the almost universal habit of dishing out a blister and then just filling it with epoxy filler and barrier coating over. We would never do this in our yard, it's just not proffesional (although many pro yards still do it this way because they have a short warranty and it's quicker). We dish out each blister and then glass them back up with alternating lams of DB1708 and CSM, finishing with a few layers of CSM rolled out fair but just a little high. Then we grind fair. So there is no fairing compound below the waterline unless its a double peel and then its just a thin slick over the whole bottom. I believe filling a blister more than about an 1/8" deep is a certain recipe for solvent retention followed by vapor popping and blisters. These blisters are caused by the solvent retention eating the fairing compound, not by osmosis. This is why you will get recurring blisters even under 2000e if you use this common technique. Having ground into hundreds of boats in all stages of the blister process, including the many warranty jobs we did in the old days before we dialed in the recipe, I'm quite sure this is the case. I have seen it many times. A boat with a preexisting bottom job with barrier coat will come in, the owner cursing whoever did the job last for applying the barrier coat incorrectly. Then I peel it and it's immediately clear that every single blister is in a previously repaired spot that was just filled. This is one reason we have a ten year warranty and haven't done a single bit of warranty work in the last ten years. The other is of course the hotvac.

I know what DB1708 is but what is CSM?

Thanks

[minaret]

Originally Posted by Ironhorse74

I know what DB1708 is but what is CSM?

Thanks

Chopped Strand Matt. If you have a lot of blisters of a fairly uniform size you can cut out a whole bunch of little circles of matt and biax in the appropriate size to lay them up. Usually end up cutting hundreds of little pieces about the size of a quarter and a silver dollar. When laminating keep a scrap of matt handy and after you do the whatever layup you decided you need to match the average depth of the blisters you can tear off little pieces of matt to fill any lows with. It's important to tear not cut the matt when filling lows, as this gives you great control over just where the fibers end up. Hard to explain but obvious once you do it some. Use a stiff laminate roller that is long enough to "bridge" the blisters you are repairing. Once you've done a few you'll see that as long as the lam roller is touching the original layup on both sides it's very easy to get a surprisingly fair layup. I always go just a little high and then grind fair, if any of them turn out low you will have to fill them an extra time. When you grind fair it doesn't have to be perfect if you have peeled and dried the bottom beforehand and are therefore planning on epoxy coating the bottom and applying fairing compound, you have a little leeway in that case. When I grind I usually hit them with a 16 grit grinder first till they're just a hair high and then finish with a 36 grit softpad. As long as you plan it out and get all the blisters in one layup schedule it all goes very quickly, often faster than filling would, because if the blisters are very deep and you just fill them it may take 3-4 fills with sanding in between to get them fair whereas you can glass them high in one pass every time. It's also much cleaner and easier to laminate overhead than to apply large amounts of fairing compound overhead, and I say this although we use mixing machines and a large crew of very experienced pro's when we do it. For us slicking a bottom with epoxy is at least a five man job, but one man can easily laminate away all day on blisters and get them done. If you do it all in polyester iso or vinylester you will save a huge amount of money over the many gallons of epoxy it takes to make enough filler to fill all the blisters on a sizeable blister job. Costs less, easier to do, and gives a much better result IMHO. Hope that makes sense.

[Kestrahl]

Originally Posted by casual

Bash Wht doese any boat built in 1986 have to have Blisters?Any othet troubled years? Just Curious

We have a NZ production boat from 1986 and they must have been onto it abit earlier here as it has quite a thick vinylester coat instead of gel-coat and a dry reading on the moisture meter. Which is great because it is balsa core below the waterline!. Locally its more the 70's and early 80's boats that seem to suffer.

[casual]

To Minarat,Your advice is First on my list,OK here is the deal I,am removing old bottom paint,using Peel Away and Soy Bean remover then sanding with 60 grit using a DA.I,am about 1/2 half done.The Gel coat is still decent,and I,have discovered No blisters so far I,have about 10 areas where it appears blisters were repaired in the past,none showing any signs of reoccourance my first thought was to open the areas and uses mat to refair how ever none appear to be larger than 2" and all are solid.Shoul I,just finish the paint removal lay on a Barrier Coat of what will be the big question,I,am considering Vinal Ester over Epoxy simply for ease of use.
Any and all comments will be Greatly appreciated.
Thanks

[minaret]

Originally Posted by casual

To Minarat,Your advice is First on my list,OK here is the deal I,am removing old bottom paint,using Peel Away and Soy Bean remover then sanding with 60 grit using a DA.I,am about 1/2 half done.The Gel coat is still decent,and I,have discovered No blisters so far I,have about 10 areas where it appears blisters were repaired in the past,none showing any signs of reoccourance my first thought was to open the areas and uses mat to refair how ever none appear to be larger than 2" and all are solid.Shoul I,just finish the paint removal lay on a Barrier Coat of what will be the big question,I,am considering Vinal Ester over Epoxy simply for ease of use.
Any and all comments will be Greatly appreciated.
Thanks

If there's no reoccurence then by all means just coat over them. They probably aren't very deep. I much prefer 2000e for many reasons when it comes to barrier coat. It pays for itself in work saved IMHO. How do you like Peel Away? I personally can't bear that stuff, it's so incredibly messy. I'd rather grind the bottom any day, much faster and cheaper. Put away your 60 grit and get some 36 grit, anything finer than 36 on a bottom prior to coating is a waste of time. The barrier coat will fill the 36 grit scratches just fine and they will dissappear about coat 3, while also providing really stellar tooth for adhesion. Since you have to sand after stripping anyway, I don't see the point in using stripper. I can usually sand a bottom paint removal in just slightly longer than it takes to sand for prep after stripping. Try doing a search here on this subject, there are many old threads on this subject. I have already preached the gospel of the softpad sander here too many times to go again.

[casual]

minaret,I,know you can,too many birthdays tell me I.can't. Use too grind a bottom in a day 36 ft boat.Those day's are passed.I,only used one gallon of peel away got 4 coats of paint off after staying on 7 hours,I,am sure it would have done more if it had stayed on longer Mess is not the word for any of that stuff.I,tried Soy Strip from Framer,works better and faster than Peel away,order 5 gallons to complete the strippingWhen I,am done stripping sanding is not a problem 80 grit works fine,I,am trying to leave as much gel as possible.I,always heed your advice will use 2000 and switch to 36 grit,thanks a bunch.

[minaret]

Originally Posted by casual

minaret,I,know you can,too many birthdays tell me I.can't. Use too grind a bottom in a day 36 ft boat.Those day's are passed.I,only used one gallon of peel away got 4 coats of paint off after staying on 7 hours,I,am sure it would have done more if it had stayed on longer Mess is not the word for any of that stuff.I,tried Soy Strip from Framer,works better and faster than Peel away,order 5 gallons to complete the strippingWhen I,am done stripping sanding is not a problem 80 grit works fine,I,am trying to leave as much gel as possible.I,always heed your advice will use 2000 and switch to 36 grit,thanks a bunch.

Anytime! I hear you on the age thing, I'm getting there myself. The days when we used to bet the weeks paycheck on who could knock out their side of the boat first are long gone for me too. Have fun!

[casual]

I,still thank the Lord every day I,can do as much as I, can do,have no intention of quitting,Have seen to many friends my age lay down and next thing you know there gone.Again many thanks for your patience and help.