SO i finished my third hotcoat last night. once again, i got small bubbles all over the place. Im using Fast hardener, and have read up on everything i can get my hands on. I am in FL, and it was about 70 deg where i was working. Im using a 3" brush, recommended ADD. F, slow strokes, gentle mixing, preheating resin, you name it. I am coating over my first hotcoat attempts, so it is a smooth surface(which has been prepped). This is getting very frustrating, and I wanted to see if i can nail the last coat perfect. I plan on finishing the job later this evening, so any tips before then would save me lots of cursing and sanding. Thanks y’all.
dust particles in the air or in your buckets/brush/clothing/etc. could be the culprit. try and glass in a sterile environment (easier said than done for the backyard boardbuilder…i know).
also, add a little splash of denatured alcohol to the batch of resin before spreading it on.
are they bubbles or zits?
if they’re zits, it’s dust.
if they’re bubbles, get a heat gun; lay out your hotcoat (a roller works better than a brush BTW as far as getting a nice, thin, even coat) and then make quick passes over it; fanning the gun back at both rapidly on max setting. You’ll see all the bubbles burst as they rise to the surface. Much nicer finishes this way.
HTH
Im not glassing in the cleanest garage, but it doesn;t look like that is the problem. It seems like most are bubbles in the resin itself. However, in the bucket there are very few bubbles, and most are large. Ill try to take some pics of my latest hotcoat.
In the past I’ve had the same problems. I think one culpret is that you might have taken too much resin off during the lam coat. With so much air in the eps it really wants to make its way out (are you using 1 lb or 2 lb?) Did you seal the eps?
Im using 2 lb EPS and i did seal the blank. Dan, your explanation makes sense for my first hotcoat. But i am already on my 2nd hotcoat (or glosscoat) because my first one was so poor. I had sanded the first one down well, and there are way too many bubbles for it to be blowing off the blank. The weave was not the problem this time around. I didn’t run my resin through a strainer, could this be the problem??? is that even necessary with fairly new resin (purchased 2 months ago)???
I just re-read Greg Loehr’s stuff in the archive, and I think the bubbles may be a result of your using a brush with thicker bristles than he’s talking about. He recommends “white-bristled” brushes, which I think may be a pretty fine bristle, like fine hair. If you were using thicker bristled brushes, I could sorta see more air getting in as it goes on…?
Just an idea. Maybe Greg will post up with some more brush info. This is the one issue I’m most scared of in starting my #1–well, that and fin box exotherm…
and doing a stringerless single fin with a starfin…
I think that’s it…
Greg Loehr or anyone that isn’t getting RR bubbled hotcoats–got a specific brush/bristle number, or a SKU number from your supplier?
I use the 4" foam brushes. They work pretty well.
I usually get zits, because up till now the shop I have been using is not even close to being dust free.
Haven’t had off gassing issues, 'cause I always try to glass it in falling temps.
They maybe little craters, like popped bubbles…if this is the case, they are fisheyes. Post a pic.
Your previously-sanded hotcoat might also have been too smooth. If that’s the case, and your resin takes too long to set up, it can go past the nice self-leveling phase and into a kind of clumping phase as the cross-linking occurs. That can leave voids in between the areas of fastest curing. Any time I’m glassing or hotcoating over another epoxy hotcoat (like capping finboxes or glassing on fins) I sand the old hotcoat to just 100 grit. If you went to 150 or 220 or more, it was too smooth.
Campbell,
I feel your pain, but with the help of folks here, I now have bubble free coats most of the time.
Check this link, it’s how I do it:
If you do not have the X-55, just up the DNA from 1cc/oz resin to 1.5cc per ounce resin. As for brushes, I have found that my best coats have come from some WalMart 4" synthetic bristle brushes, came 2 to a set, around $5-$7. Pricey, so I just went to Harbor Freight and got a box of 4" chip brushes, less than a buck apiece. They work well. Be careful with the heat gun, practice on some scrap if you can, as leaving the heat gun on the resin too long is more disastrous than the bubbles it would pop. It leaves a cratered surface.
Wash the board before coating, I use Dawn detergent and the hose, towel dry and brush off/blow off the lint from the towel. Use gloves to tape off the board (pain in the ass for sure, as masking tape loves latex).
Straining won’t necessarily help with bubbles, but it sure gets some larger particles that will become zits if you leave them there. Try not to have any drafts blowing on the board as it cures.
Also, don’t coat on a surface sanded to much more than 150 or 180, I only sand to 100 or 120. The resin prefers to run off of a surface sanded to 220 or more.
I have found that the most effective things are to (in order of efficacy):
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Heat the resin (2 sec per oz of resin in microwave, for my microwave, at least)
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Thin the resin (with F and DNA)
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Do not brush for too long (with heated resin, it tends to ‘gel’ faster, and moving the brush over thicker resin gives bubbles)
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Leave it alone when you are done brushing and fanning with the heatgun (briefly, the heatgun is not a cure-all). The more you mess with it, the worse it gets.
I’m sure that heating the board would be up there with #1 or #2, but I don’t have a good way to heat the board without getting it dusty/dirty.
These are just my experiences and observations, and I hope this helps. Let us know how it goes,
JSS
Howzit Campbell, Seems that if you have done more than 1 hotcoat on the same side that you should be able to sand it and the bubbles will dissappear by the time you get to the level of the first coat since the second should have filled in the first coat bubbles. Best scenerio would be that it’s zits from dust.Aloha,Kokua
Hey guys, i forgot to snap pics of it before i hit it with the sander. I think the problem was probably the dust. Once i gave it a couple passes with the sander, they all smoothed out. Not the flattest surface ever, but after a good half hour of sanding… i finally have a flat/smooth bottom. I am planning on hotcoating the deck tonight, inside… away from all the dust. I guess thats what i get for glassing in the same spot i sand/prep. I am going to try the foam brush this time… and might throw in little DNA to try it out
Will there be bonding issues between epoxy w/ DNA added and w/o DNA???
my deck is a much smoother surface, so this one should go on much better.
I plan on drilling a though-board leash hole in the back of the finbox… should i wait till after last hotcoat??? thanks for all the input. I am so close to being done, couldn;t have done it without sways . I will post some more pics too .
Campbell,
If you are working inside with Additive F, wear a respirator with organic vapor cartridges, and air out the place afterwards. The solids in Additive F are in a Xylene solution if I remember correctly, and it is a potent carcinogen. Breathing it is just like shooting it into your bloodstream. Also, if you use DNA or F inside, remember it is flammable stuff, so don’t have things that can spark hanging around. The resin and hardener by themselves are only mild mucous membrane irritants, and with adequate ventilation should not pose a problem, but do not mess with Xylene, even in the small amounts we use. A $25 respirator is less expensive than medical bills could be later.
I have never had any bonding problems with DNA, but I have always had a sanded/roughened surface to bond to. I believe most of it evaporates, especially with heated resin. Greg posted that up to 5% by volume is OK, which turns out to be a little less than 2cc per oz of resin (I am not counting the volume of the hardener, so my calculations are off on the conservative side). The problem if the DNA stays is one of altered physical properties. There is a link somewhere that talks about epoxy thining with DNA, Acetone, and Lacquer thinner, and the changes to the physicals of the epoxy. Here’s the link:
http://www.seqair.com/skunkworks/Glues/WestSystem/Thinning/Thinning.html
It talks about West System Epoxy, and it may not have the same composition as RR, so the graphs may not be accurate. Also, considering the vapor pressure of acetone, I would guess that it would evaporate faster than lacquer thinner, but I realy have never compared the two, and I have not had a problem using DNA at the 2-3% I normally use, but I haven’t done any breakage tests with and without DNA either.
As far as the leash hole, I drill the hole through the deck before I put in the box, and cover it with tape, so there is nothing but box and resin to drill through after gloss. I would do it before sandind the top, after hotcoat. Drill from the top, do not go through the finbox, to avoid having to prevent resin from getting inside the box. Fill the hole with resin/filler from the top, and sand as usual. After you are done with wetsanding, drill the hole through the resin and the box, and put in the leash loop. There may be a better way, though.
Good luck,
JSS
Quote:
and it is a potent carcinogen. Breathing it is just like shooting it into your bloodstream. Also, if you use DNA or F inside, remember it is flammable stuff, so don’t have things that can spark hanging around. The resin and hardener by themselves are only mild mucous membrane irritants, and with adequate ventilation should not pose a problem, but do not mess with Xylene, even in the small amounts we use.
SO.
Is anybody else freaking a bit on this information (that I didn’t know at all?)
hhmmmmmm…
I did some looking a while back, from what I had gleaned … Xylene was a known neuro toxin (nauseau, dizziness, headache, poor concentration, nervous system depressant…etc…) . It was unknown for sure, but suspected as a possible carcinogen. Maybe Maxmercy can give us a link to the info he found on it.
I have worn a mask when working with it, but my shop didn’t have good ventilation, so it was a little thick in there…
Soo many carcinogens out there…
My new work space will be setup with some good ventilation.
Always play safe people.
You guys are correct, the EPA does not calssify Xylene as a carcinogen, but it is suspected, and in the research labs I have been familiar with, safety protocol treats xylene/toluene and most simple aromatics the same way as benzene (which is a carcinogen). So, that’s why I said I believe it is a carcinogen (I should not have used the word potent), I have only small bits of data to support this, like:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=3053447&dopt=Abstract
http://www.oztoxics.org/ntn/xylene.htm
http://www.atsdr.cdc.gov/hac/PHA/CooperPoyntElem020905-NJ/appendixc.pdf
Actually, I didn’t read these articles before I got a respirator, I just asked a friend who currently does graduate work in a medical research lab, and he told me to stay away from them if I can. That was enough for me.
Most governmental agencies and chemical companies do agree that there is not enough evidence to prove that xylene is carcinogenic, but that further studies may be warranted. Remember also that the concentrations necessary to cause malignant neoplasms (cancer) may be astronomical, and more than we ever deal with glassing a board. But due to the neurotoxic, hepatotoxic, and nephrotoxic properties of xylene, as well as possible carcinogenicity, I thought I would wear protection just for insurance.
Simple hydrocarbon substituted aromatics penetrate cell membranes quite easily, so there really is no place in your body that is protected from these chemicals once ingested or inhaled.
Like I said before, I just wear the respirator for insurance, and hopefully those links above will convince some people that it may be a good idea as well. Cigarette smoke contains tons of carcinogenic compounds, but some people smoke all their lives without a single major neoplastic event. I just thought that I would better my odds at not dealing with health problems later on.
There appears to be a latent opinion that epoxies are ‘safe’; and yes, compared to polyesters, they definitively are. I would still warn people that adequate ventilation is still necessary, and so is skin and mucous membrane protection, in my opinion. If adequate ventilation is not to be had, wear the respirator, and ventilate the room after work is done, or leave.
Sorry if I freaked some folks out. We are exposed to lots of harmful substances every day, most of which we have no control over (like breathing vehicle exhaust, for example), but this is a case in which we do have some control, so why not exercise it?
JSS