this has been a constant battle for me while epoxying the inside. the issue is that one coat of epoxy just never kicked. i know i had the mix right, i know i applied it just fine but it never kicked, so i got smart with the advice of Barnacle Jim and just decided to add another coat. this worked fine for most of the areas, but i have a few have nice blisters in areas.
what i am going to do now is get out the big 6" porter cable sander with some 36 grit paper on it and sand it all down to past the non-hardened epoxy and start over.
what i have noticed when doing this in some of the areas is that it turns a milky white and will not clear out as soon as new epoxy is applied. is there a better way that i do not know of to avoid this? i have tried cutting it with acetone and scrapping it off which cuts it down a bit but leaves it still somewhat white.
There are only a few reasons that your previous epoxy batch didn't cure, none are easily fixable unfortunately. As I'm sure you've heard, it should come off the surface and be prepped back to solid material (epoxy or wood). If not, you're just putting a hard coating over a soft, gooie coating, which can't lead to much good in the long run.
There are many wife's tails about adding straight hardener over a bad batch, washing down with vinegar, applying hardener rich over coats, etc., but none work, certainly not very well.
I've made "5 pump" epoxy runs using 5 good pumps of resin and five good pumps of more resin (thinking it was hardener) and everyone else that's done any epoxy work has too. It happens, even though we clearly remember pumping both parts into the mixing pot.
Your blisters will grow and provide you with off spring (they'll breed, trust me) it's the nature of this sort of problem. Just moving about inside the boat can force uncured resin around under the cured coat, which will delaminate the cured coat, creating a blister.
The white goo you're running into, while trying to clean the affected areas is likely air bubbles and trapped solvent. Acetone isn't the best epoxy cleaner upper, try white vinegar. Epoxy is a very alkaline material and vinegar is quite the other, also an excellent cutter (cheap too), plus has the side benefit of stopping the reaction, which acetone doesn't do, unless you uses gallons of the stuff. Alcohol is better then acetone and also a cheaper, more effective cutter.
You're going to have a maintenance issue with this sooner or later. You might as well get it taken care of now, before uncured goo is tracked all around the inside of your boat, from broken open blisters. I know it sucks, but grind it back to the goo, try to clean it up the best you can with a cutter, then grind some more until you have a solid substrate to work with. Unless you apply epoxy over "green" epoxy (partly cured) it relies on a mechanical bond to the previous surface to have the grip it's famous for. It can't grip goo too well. You'll gum up a lot of paper it the early going, but you'll get through it. An old trick some builders use, is to add dry pigment to the hardener so it's plainly obvious if both parts are in the mix. A tea spoon directly in the can after you open it, shake the crap out of it and let it sit until you need it. You can get dry (powered) pigments at a paint supply shop.
I was afraid of that. I shared my experience with you. It took over a year but the blisters formed and as PAR mentions, they had off spring.
Barnacle might heed your warning. :lol: You are on the right track, you gotta get the bad batch off before you keep going. Steady on Bill, steady on.
Bill,
I had a similar issue when I epoxied the bottom onto the keel and the joiners between those panels (I got the ratio of epoxy to resin backwards). I ended up having to take it all apart, scrape off what I could (which was at bubble-gum consistency) then scrub vigorously with a green scrubby pad from the kitchen and acetone. The up side was that it did a really good job of cleaning it all off and there was no residual smell when I was done (I imagine you might have a boat that smells like a pickle if you used vinegar), the down side was that during the actual cleaning, the acetone was pretty stinky and that my fingers got mighty cold as it evaporated during the scrubbing (the rubber gloves didn't help with that).
I was pretty depressed with the amount of work required when I first realized how much scrapping/scrubbing I would have to do, but once I got rolling it went pretty quick - an hour or so a night for less than a week.
Good luck!
John K.
Hi Bill,
Blister me timbers! This is terrible news, Bill. At least, though, the problem seem fixable.
I had a long talk with Barnacle Jim the other day. He claims his boat has no blisters. I suggested that he might have something to look forward to in the future. He respond by asking me about the infamous man overboard drill, asking me if I might like to participate.
Bill, sorry the solution did not work for you. Epoxy seems as sensitive as the human hand it sometimes dries on. Maybe the semi-hard surface will help with the sanding. Sanding chewing gum consistency just doesn't work.
Part of my problem, Bill, was not in the reversing the ratio; it was in the stirring. I needed to stir the mixture another 2 minutes, or close to 3 1/2 minutes total. I also needed to work with larger batches to keep any inaccuracy to a minimum. As far as I can tell, all layers eventually hardened with no blisters or soft spots. One or two of the batches took days to hardened. Now, however, all the mixtures seem to be behaving. I attribute the difference to the size of batch, and the length of time in the stirring.
My advice to anyone using epoxyâ when you think you have stirred the mixture enough, stir it yet some more.
When I screwed up my batch, I broke my standard practice of always mesuring resin first, then hardner. The ratio was exact. Exact, but Exactly Bakwards.
Worst of all, I was slathering upside down through my forward hatch. Needless to say, when I figured out what I had done, the cleanup, also upside down in the hatch was a b@#%h!!. Since it had no intention of getting anywhere neer hard, I was able to wipe most of it off with paper towels.
Anyway, there are things that will make you
more red in the face then just mixing wrong
Stephen
I use several different types of epoxies, two penetrating and six different laminating goos. Some of them can swap hardeners and resins, but a few can't. The ratios are all over the place from 1:1 through 5:1 so it's easy to screw up (a well tested theory around here sometimes).
I find there are two major problems that creep into the epoxy woe's handbook, adequate mixing and correct resin to hardener ratios.
I have mixing down to an art, small batches are mixed by hand in a flat plastic tray with a putty knife, using the "folding" method. This where you skid the blade along, picking up some goo, then quickly flip it over at the end of the stroke and mash it into near by goo and drag the putty knife blade back toward you. This must be done on a flat surface so paint tray liners are out, I use those disposable "Tupperware" kind of things you can get at Wal-Mart. They have rounded inside edges, which makes getting the goo out of the corners easy. On batches over a few ounces I use a paint mixer thingie on a drill, which does a great job and quickly.
I always add filler on a flat board. A scrap piece of lauan has been doing the deed for a while now, surviving many flattenings with the belt sander. I use it as a mason's hock and apply thickened epoxy directly from it. The large surface area, permits spreading the epoxy out into a very thin layer, which has a much longer pot life then a glob of goo, in the bottom of a container.
Dispensing pumps aren't the most accurate things and can be off enough to fool with your ratios. I pump or pour into small plastic drinking cups, which I place inside another cup that is pre marked with the correct ratio. I reuse this "graduated" cup until it's to gooie to keep in service, when I mark up another set. Most of the time the pumps do a close enough job of it, but sometimes you'll catch a "short sheeted" amount. The plunger may have been partly depressed, stuck or not a full stroke was provided, but the graduated cup will catch this and save a headache. Most of my epoxies don't have pumps, so hand mixing is pretty normal for me.
All the epoxy resins live on the left side of the epoxy table and the hardeners on the other. In the middle I have the dispensing and graduated cups, paper towels, gloves, mixing pots, etc. The epoxy never leaves this 48" square of 3/4" plywood, only the mixing pots with goo in them do. This keeps all the mixing and ratio insurance materials at hand. The lauan hock or the mixing pot is taken to the work area with whatever I'll be applying it with. This may seem a touch anal, but it keeps the procedure easy to follow, reducing the possibility of mistakes. Mistakes will happen (remember how pissed I was when I glued a new mast to my work bench last year) but strictly sticking to a procedure will help a lot.
Hang tough Bill, you'll get it licked.
Hi Paul,
Thanks for the tips. At times, epoxy can be frustrating, very frustrating. Since applying epoxy often means rushing to get the job done before the substance cures, it's easy to make mistakes. You want to rush because your time is limited, you discover the knife you were using needs cleaning, you overlook the cup of resin near your elbow and suddenly, with one slight hit, resin is spilled on you and on your working surface. And to make matters worse, you need to work overhead in some small and cramped area of the boat. Worse of all, the pump sputters as you try to mix a small batch just to finish. Well, you know the story.
Paul, is there a shelf life to either the hardener or the resin?
Just wondering what kind of wood we're dealing with here. I know that I've had some non-cure situations in the past as well, most of them that were not mix ratio goofs wound up by being incompatibility with the oils that were in the wood. That prevented the resin from kicking off.
The oils in cedar and teak as an example can cause adhering issues in some cases.
The Mfg of the epoxy recommended that I wipe everythind down with acetone prior to applying the epoxy when that happens. This cleans the surface and for me at least it took care of the issue. I also found that with White Oak as an example that it really doesn't like epoxy at all. But will accept other adhesives just fine.
The acidic nature of some woods (the tannins in white oak for example) can screw with epoxy bonds. A wipe down with acetone or alcohol will remove the offending material, but needs be just prior to applying epoxy. These acids will actually stop the reaction, prevent the cure process from completing and making a gooie mess. There are other materials that can play with the reaction or bond, prep and procedure is the name of the game.
Know your enemy. You have to be religious about doing epoxy work for near constant successes. Do a "dry" run where you actually go through the motions of the laminating, bonding or coating process. You'll quickly note the putty knife needs to be hit with the belt sander, the box of gloves only has one left in it, prime the pumps with slow steady pushes, until you get a solid feel and some epoxy at the spout with the least amount of force on the pump, etc. Is the site ready (dusted, tacked and wiped with solvent), is the mixing area ready (enough pots, mixing sticks, gloves, paper towels, etc.), is the work ready (positioned to receive epoxy and assemble, etc.), then suit up and get to it.
It is a mad rush sometimes, but this usually can be traced back to skipping a step or two in the "procedures" you've developed and now have to make up for it as the goo is kicking in the pot and you're running around looking for a better putty knife.
Hardener in a can will discolor in time, usually to a pretty reddish. It does have a shelf life (according to the manufactures) I've used epoxy that was a few years old (a quart can was opened, fell behind a work bench and lost until I moved the bench a few years later) This went to good use, showed no signs of being extra brittle or not curing and is still in place on one of my boats (didn't want to try the experiment on a client). Another thing to look for in old epoxy is "crystallization" which can happen if it gets real cold (just warm it back up) which will make it kind of milky or cloudy. This epoxy was more yellow when cured, but the hardner was about 6 months old and had some color in it too.
It's a good tip to wipe all surfaces before you use epoxy, though acetone isn't the best choice all the time and can be the wrong choice some of the time. This is part of knowing your enemy. Some materials will be more difficult to bond or coat. Learn about the materials and products you'll be incorporating into your pocket yachts or any other project you find the need to use epoxy on. I fixed a soffit and the mail box last month using epoxy and some filler. The repairs will out live the originals. The soffit was cedar so an acetone wipe was necessary (the tannin thingie again), but the mailbox was plastic and would have been attacked by the harsh solvent, so alcohol was the answer, plus a very aggressive roughening with a 36 grit disk on the orbital, to provide healthy tooth, for a mechanical bond.