I’m having a problem with bubbles using Resin Research epoxy. I have not used any other epoxies so I don’t know whether the problem is with Resin Research or my technique (probably the latter). With this coat I was meticulous with my preperation to ensure that it was clean. Last night I wiped down the board with a rag, then a rag with water, then several different times of wiping in down with alcohol. I let the board sit over night to make sure that any dust in the air had settled. When I got up this morning I wiped it down with alcohol again and let it dry. I proceeded to gloss coat the board. I mixed the resin EXACTLY (to the nearest gram) and the required amount of Additive F. I mixed extremely slowly to ensure that no air bubble got in the mix. I spread out the epoxy extremely slowly to ensure that it didn’t foam or get aggitated in any way. It looked perfect - not a bubble to be seen on the board. Satisfied that I had done everything correctly I went inside. One hour later I came out to the garage and this is what greeted me. If you look very closely you can see that they are tiny air bubbles. Does anybody have any idea what is causing this? Do I just sand it and polish it like normal?
These pictures are taken vary close to the board so it makes it look worse than it is, but I am unhappy to have this happen again. Any help would be appriciated.
that dosn’t look like problems with the epoxy it looks like good ol’ pinholes… there are many ways to deal with em’…
a wetter lam will help…
after you do the lam squeege on a thin layer before fill coating…
be sure the board is cooling while fill coating…
with this one i’d say sand it and perhaps go and put a drop of resin on each hole, sand, and then gloss, or you could just sand and then gloss and then fill each little hole and then sand/polish…
another thing i was thinking about doing was before bagging on the glass squeeging on a thin layer of resin, a sealer coat if you will…
i just went and read over you post again and see that it is a gloss coat…
try sanding it and see what happens… sometimes that stuff is just on the surface and will sand away…
I think that is “blow through”. Trapped air in skin core warming up, escaping thru what must be a non-airtight lam/previous layer.
I’ll guess that its the gloss coat. If thats so then both the lam and the filler coat have some tiny pinholes.
I have not found the answer to making an airtight lam - i find its impossible (i vac bag too). So filler coat needs to seal the lam, and i’ve had problems achieving this in the past. The solutions i use are
(after the lam has cured and no need to wipe lam) to squeegee on the fill coat, not brush. This will force resin into the gaps in the cloth weave. Conventional glassers call it “basting”, i call it bogging coz i load up my filler coat with micro-balloons - i suppose you won’t want to do that for cosmetic reasons).
Keep the board in a very warm room (I stuff it in an old vacuum tube to keep the room clean, then put the heater on full in my bedroom and leave it there for an hour or so).
While board is warming up, prepare for the epoxy coat procedure.
Make sure that epoxy procedure takes place in cooler temp than warm up room. skin core should then inhale resin into gaps rather then blow thru.
Sand filler coat.
If filler coat has pinholes, do another baste/bog - sand and repeat as necessary. I have got away with using just a tack cloth to wipe in between sanding and coating - no cleaning with alcohol or anything else and achieved a perfect seal.
repeating the baste/bog doesn’t add any noticeable, weight if you sand carefully afterwards. I find it too hard to try and fill the holed areas only - easier and safer to just re-bog an entire deck/hull then sand the lot again.
So if i was in your position now, i’d be concerned about the sand and polish breaking the bubbles and giving you a porous board which will suck in seawater. I would therefore sand carefully, leave in heated room etc and do a baste. I haven’t found RR is more prone to bubbles than other hi-quality epoxies.
but thats just my diagnosis/opinion and i should mention that my boards aren’t built for looks, in fact they look awful. But the successful ones don’t leak [smile]
I was surprised at a) how quickly b) how much water got sucked in to a pinholed #1 eps/corecel sandwich I made [frown] Therefore i don’t think the drastic step of sanding and re-basting is overdoing things, particularly with your balsa skin which may warp if penetrated with water.
I had problems with the hotcoat on this side of the board so I had basted the board to try and fill the holes. What you’re saying makes sense but if you had seen how filled the lam looked its hard to imagine so many micro holes.
By the way, I didn’t want to imply that it was the resins fault. With this only being my second board I suspect the fault lays with my technique.
I’m laminating a 6’11 clark foam twinzer with Resin Research Epox that’s near completion that I’ll be posting a few photos of soon.
Three of the most important things that must be addressed when working with epoxy is existing temperature, temperature change and cleanliness.
I follow the following proceedure with lamination and fill coats.
I don’t find any reason to use Additive “F” in the lamination proceedure as the the cloth accomplishes the leveling action itself.
I sand to 80 grit for the first fill coat and 400 wet/dry for the finish coat. I wipe the board with a paper towel soaked in denatured alcohol just before I apply resin over resin.
While the last of the alcohol evaporates from the board I proceed with mixing the resin.
I am always careful to work resin on to the board when it’s temperature is falling. If room temperature is falling so much the better. I often sand in the direct sun and take the board inside and apply resin right afterwards in a nice quiet dust free environment. I don’t have any trouble with off gasing.
With fill coats I use a generous amount of Additive “F” which I get up to about 120 degrees in a hot water bath before I start the procedure. I mix the “F” into the hardener thoroughly. The resin and hardener is kept at about 70 degrees. When the the “F” hits the hardener it breaks into cloudy flacks I believe because of the temperature change but this doesn’t affect the surfacing activity. I pour in the resin – stir and stir and stir. Let it stand for about a minute to let any air bubble rise.
I get the majority of the resin out of the pot quickly leaving just a little in the pot for the spot that needs it most.
For fill coating I brush out the material very thoroughly brushing in several directs finishing but stroking the length of the board very lightly. If any low spots occur in the first 30 to 45 minutes of curing occur I apply a dot of resin with the stir stick from the bottom of the pot and with very few exceptions the spot will fill in nicely because the resin is in it’s thickening process and the increases surface tension holds it in place – an overnite cure and it’s on to the next step. For high production work proper use of a hot box accelerate wthe production of the same results.
Thanks that does help! I have a theory of what might have happened. I bet the problem started with my bagging technique. I’ve noticed that most of the problem happened with the bottom of the board. I glassed the bottom of the board first so when it was time to get it in the bag it was more cured than the deck (I did them at the same time so the bottom was tacky while the deck was very wet). The vacumm pulled it together enough that in was looked really good. I started hotcoating the bottom of the board and it was looking good. It reached the tacky point that Halcyon was talking about and I took it outside. Even though I had a vent there was enough gas in the board that the rise in temperature drove the gasses out of the board making bubbles. Since the resin was tacky the bubbles hardened as open little holes. Even though I basted the holes I probably didn’t seal them all the way. I started glossing this morning and there was a slight rise in temperature while I was working. I just glossed the deck and so far it is looking good.
The question now is what do I do to fix all the bubbles on the bottom of the board. While the resin was in the plastic state I used my gloved hands to smooth out the bubbles as best I could.
Once the resin has become very gummy you can accelerate the curing process by elevating the temperature.
In order to get rid of the bubbles, though it’ll be a little tedious. I’d use a single edged razor blade and open each hole up into a little cone. Then mix a same batch of resin with Additive “F” and use the stir stick to put a dot of resin over each cone. Be sure the temperature is dropping during the first hour of cure time and you’ll be able to fair all the resulting bumps out. Along with having a sealing up all the vent holes you’ll have a very nice cosmetic fix.
Finish process note:
The board (6’11"x22.0"x3.125" twinzer) I’m working is now sanded to 150 grit dry. I’m going to do a little lining and lettering on the deck so I’ll wet sand that to 400 do markings on the deck and shoot a finish coat over them of about 6 oz. of resin mix with “F” in it. The very smooth surface won’t much material for a good finish and I don’t really want to add lots more weight to the board. Once the finish coat is on the deck I’ll sand the deck to 150 dry like the bottom and then take progressively wet sand throught the grits to 1200, polish and wax. It won’t be a pretty as a poly job but it’ll be one whole hell of a lot lighter and much more durable.
though it’ll be a little tedious. I’d use a single edged razor blade and open each hole up into a little cone
I was afraid you were going to say something awful like that. I’ll give it a shot as see how my sanity holds out. There are loads of bubbles. Thanks again!
I just got back form the garage and I’m amazed. I went out to see how awful my hole popping adventure was going to be. I flipped over the board to make a test pop and there were no bubbles to be seen, only bumps. I could believe what I was so I decided to hit it with some sandpaper and it looks perfect. I can see no trace of the holes and it is completely smooth. I think that my Squish Them Where They Lay approach worked. When the resin was in a plastic state I pushed all the holes until they were flat. I might have lucked out! Thanks again everybody for all the help.
Next time keep it out of the sun until fully cured. As Rich mentions, a cooling state is better than a warming state. Every grain in the wood is like a little compressed air capsule waiting to outgas with heat.
Using UV resin for ding repair, I’ve had fits with the same issue especially on a stringer.
Howzit John, After using UV resin for a few years now I've come to the conclusion that the UV catalyst tends to perculate as it kicks which cause some air. But I haven't seen it in lamination only when using Q-sel or thick resin apps. What brought me to this conclusion is I notice deep air bubbles in the finished work and that got me thinking about how UV works. I may be wrong but it's a feasible answer to the question.Aloha,Kokua
Hey Dan, part of the problem had to be when you said you took it outside. The heat cycling thing is called Post- cure for a reason It was also early morning, so everything was just getting hotter. Do it exactly the reverse next time - leave the board out in the sun in the afternoon while you’re mixing & setting up. When you’re ready to gloss, it’ll be nice & hot, run it inside & paint your coat on.
Glad to hear it worked out anyway. That kind of stress is just so disappointing until the solution appears. The board looks cool
Glad things worked out. I think you stumbled onto one of the good things about epoxy that I stumbled onto a while back. I’ve used a bunch of different epoxies and have had pinholes, fish eyes, pits, ect with several. But what looks like a disaster can often be squeegied out after it has thickened a bit. Of course it’s better to have everything go perfect but if it doesn’t many things can be salvaged if you just wait a while. Unlike with polyester resin where you try to get everything sorted before it suddenly hardens epoxy gets thicker and thicker and eventually gets hard.
Also its amazing how much eps can off gas. I was fixing a puncture hole in a board the other day where our Labrador had grabbed hold of the tail when he decided he didn’t want the kids to go in the water. It was mid morning and my shop was heating up a little - not a lot. I had the hardest time getting the hole to seal. It just kept bubbling up.
You’re doing some really nice work and have brought up some great subjects in your posts. I’ve learned heaps in threads you’ve started.
my shop was heating up a little - not a lot. I had the hardest time getting the hole to seal. It just kept bubbling up
I never realized how important temperature was building epoxy boards. When I was heavily into the researching stage I saw a few blips here and there about temperature, but I never realized it could make nice work look awful so quickly. I never understood why I got bubbles until all the help I received in this thread. It sounds very avoidable now I understand whats going on. Thank you for the compliments. I always feel I’m walking a fine line between gaining understanding and being a pest.
Since we are talking about gassing, a lot of what looks like off gassing can be prevented in non-sandwich boards with a good seal coat, such as DAP spackel. I think some of what passes for gas (wow, can you believe I worked that into this thread? ) is just drainage into the foam. I’ve gotten much better with spackel and my boards are coming out mostly bubble free, regardless of the temp. My garage is 85 to 90 degrees in the summer. Yes, it cools to some degree overnight, but the resin is hard in an hour at that temperature.
However, what prompted this reply was the thought that with sandwich boards, I’ll bet you don’t seal the EPS prior to epoxy. Maybe a seal coat of some type would free you from the temperature concerns. Heck, maybe wrap the core in Saran wrap or just do a Jim Philips type micro-ballon and resin coat to seal the foam.
And Dan, thanks for all your info on sandwich boards. I, too, have learned a bunch from you and the others. I’ll doing my first vac board in a few weeks.
It was also early morning, so everything was just getting hotter. Do it exactly the reverse next time - leave the board out in the sun in the afternoon while you’re mixing & setting up. When you’re ready to gloss, it’ll be nice & hot, run it inside & paint your coat on.