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Epoxy fish eyes revisited
14 replies to this topic
Posted 29 January 2007 - 03:24 PM
Hello again all
I would like to thank all you guys here on TU who helped me with my earlier problems I was having with fish eyes and dry patches on my epoxy coatings. I think (touch wood) I have sorted this thanks to your a advice and am now looking to improve things even further. During my earlier problems I must have visited dozens of epoxy web sites and one of the vital pieces of information I managed to glean was the fact that air in a coating was expelled by CO2 and not heat, hence the method of flashing with a blow torch to rid air from an epoxy coating but I am still unsure of how much air a single flashing gets rid of. How often do you fellas do this?? It would seem that the fish eyes in a final coat are the ones that when the bubble bursts the epoxy is too thick to fill the crater back up eg. when it is well into its curing period.
One thought that occurred to me is that if a constant source of CO2 is introduced into the drying cabinet would this assist in getting rid of 100% of air in the epoxy ?? I am thinking around the lines of a small meths burner or candle, bearing in mind of course the potential fire hazards.
Your comments, ideas or experiences are eagerly awaited.
Posted 29 January 2007 - 03:43 PM
After clearing the bait we will hang it for a couple of minutes to let some clear drip off.During this time we make only a few passes over the bait with a torch and thats it before spinning. Most of the time I will breathe on each side of the bait to dissapate some bubbles right after applying clear. My question about the candle idea is would it or could it produce black smoke or soot to be absorbed into the clear ???
Posted 29 January 2007 - 04:03 PM
I am sure you are right about the candle, I dont think anyone could deny they do smoke !! I dont think that is the case with a meths burner though. I remember as a kid (a couple of centuries ago) I was bought a chemistry set which had a meths burner which burnt with a clear light blue flame and no smoke.
Thanks for your reply
Posted 29 January 2007 - 04:40 PM
Interesting thoughts and ideas.
But, while frowning at the moon crater texture of my lure, I noticed that my mixing lid was totally clear of bubbles.
I think that, although CO2 is a product of the chemical reaction, this is dissipated long before the cure. I believe that the heat of the process is causing the air within the wood to expand and force its way out.
Try heating the lures in an oven prior to application. It should reduce the volume of bubbles and the heat should allow them to break out easier. I would try it out for you, but my shoe box of an apartment does not have an oven. I would at least do a test before putting a fully painted picasso though this process.
Posted 29 January 2007 - 05:37 PM
If your wood is warming during the cure stages you will experience "off gassing". this is a phenomenon where the air inside the wood expands and expells itself out of your lure or project and is common in boat and canoe building. Daily temperature fluctuations are enough to create this problem.
If your lures are properly sealed prior to painting you will not experience any off gassing during normal tempurature changes. If you do put them into a hot box for curing you need to keep the inside temps less than 100 deg F. 80 - 90 are the best ranges and can be accomplished with a lightbulb.
If you are not seeing bubbles in your mixing cup but are on your lure the problem may lie in your application method. Some Questions to ask yourselves are:
Am I over brushing the epoxy to create the bubbles?
Is my application tool:
to stiff a bristle?
am I applying to much epoxy?
am I applying to little epoxy?
As both of you are Brittans could your problems be enviromentally related? I've never been to England but rember hearing stories of the London fog. So I am inclined to think that you live in high humidity every day. This also could cause some of the problems you are experiencing.
I have had my fair share of devcon problems myself and found that it is best to use the freshest available. Don't purchase more than you need at a time.
Posted 29 January 2007 - 05:51 PM
I would not reccomend warming lures in an oven used for food preparation. There are to many health risk possibilities present. an inexpensive and viable alternative is to use a toaster oven. often times these canbe found at thrift shops for little cost.
Posted 30 January 2007 - 01:51 AM
Point taken. In fact, I did a test after posting, on a piece of raw balsa. I heated it in an empty jar sitting in a pan of boiling water for ten minutes. The jar lid had several holes drilled in it to prevent explosion VERY IMPORTANT.
An identical second piece of balsa was coated and closely examined. The air bubbles could be seen comming from the wood, quite violently in fact. The application on the heated lure, although not totally free of bubbles, was much slower. My conclusion is that heat helps.
If the lures are placed on a hot radiator or water tank etc the situation will be improved.
Regular primers and sealers, I find, do not give adequate protection against the bubble syndrome. I seal all my baits with five minute epoxy, I accept the bubbles and after a suitable curing time, usually 24 hours, I attack with a dremel flap wheel to level the craters. The lure is now ready for artistic application of my half inch brush.
Posted 31 January 2007 - 09:09 AM
Cheesehead you have hit the nail smack on with your comments about the heating of lures in a drying cabinet.I not only dry the wooden blanks in a microwave but also seal with a proprietry sealant before applying a primer coat of paint before the finish paint.I have sat and watched very carefully these air bubbles appear and I am convinced they are coming through not only the wood sealant but the paint coats as well. The secret to eliminating these is the sealant. An impervious and rock hard sealant is needed too stop this air forcing or being forced out of the wood. We are talking tiny amounts of air but it is enough to erupt in the coating. I have not totally eradicated my air problems but have improved the situation by at least 95% so I'm getting there slowly but surely.I am sure that commecialy available sealants are not up to the job that lure makers require from a wood sealant although I am experimenting with one at the moment which is showing great results. I am not sure about humidity but I don't think the Uk is any more humid than anywhere else in Europe and I must admit I did have a little chuckle at the thought of all us 'Brit's' staggering around blindly in pea soup type fogs, it doesn't happen .
I have since my last post tried a constant source of CO2 and if anything it made things worse, I had high hopes of success but soon burst my own bubble(excuse the punn) maybe it got rid of too much air in the coating. As a conclusion I would say if using a hardwood as the material then drying at a lower temperature is a safer option.
As a footnote to this posting I have not been able to try the plastic cup in thinners method as when I tried to make some I used cellulose thinners thinking this was as good as say acetone but ended up with a liquid plastic in the bottom of the jar and the thinners on top, so although the thinners did melt the cups they did not mix with the thinners and ended up as two separate parts. I am thinking though that I may be able to paint on the plastic with a brush! mmmmm now there's a thought:lol:
Posted 01 February 2007 - 05:03 AM
i use the plastic cup/thinners method for sealing my lures the thinners i use is made by tetrosyl from car shops and the cups are the cheap nasty white plastic ones i get them from the co-op,this combo work's well
Posted 01 February 2007 - 05:50 PM
I disagree with you..... us Yanks have seen enough Jack the Ripper and Dr. Jekyl and Mr. Hyde movies to know thay you poor Brits live in constant "Pea Soup" fog.
Posted 02 February 2007 - 12:11 AM
I have fought fish eyes and dimples forever. I think the fact that I'm building big lures is part of the problem. I have found it helps to keep the temp a bit low (around 75) during the first coat of clear and to experiment with various woods...the harder the wood, the less bubbles. I will also add that at times it appears as if some interactions are occurring between the paints to cause the fish eyes. I don't think a sealant is the entire answer because I have tried them all!!
It's a hassle for sure and if anyone could find a way to get rid of them I would be very interested.
Posted 02 February 2007 - 02:01 AM
I top coated a balsa bait last night at room temperature. Because it was originally sealed with epoxy, I was not concerned with the possibility of craters and was anticipating another perfect finish.
The chemical reaction heated air inside found a weak spot in my seal coat and burst through just before the epoxy went off. The resulting crater was 8mm dia.
An Idea for balsa baits would be to deliberately introduce a fault with a pin, in a convenient place were the damage would be minimised. This could prevent damage by letting the air out sooner in the process, while the epoxy is still fluid. Just an idea I'll be testing this weekend.
Does anyone have any feed back on the 'heating' method.
Posted 02 February 2007 - 02:31 AM
I'm relieved I am not the only one in the war against fisheyes, it seems just as you think you are getting to the solution for these things they suddenly Plaster of Paris out of the woodwork and kick you back down again:lolhuh: it can be quite depressing. It sounds like you are making baits like mine and I agree the larger the bait the more acute the problem, also flat sided lures are the culprit, I have made some round sided lures with no problems at all I really can't get my head around why that is.
I propose a fisheye competition, Vodkamans 8mm beauty must surely be a leading contender