Discussion in 'Rod Building' started by LoonhauntDave, Sep 17, 2007.

  1. I am refining my epoxy coating technique for overlayment of appliqued designs and guide wraps, and am having some issues with entrained air bubbles in the formula I am using. I am currently utilizing Flex Coat brand epoxy. I am happy with the final finish but I end up having to perform a lot of wet sanding to get rid of bubbles and dents from popped bubbles. The manufacturer recommends letting the mixed material sit to allow bubbles to rise out of the mix. By the time that happens the mix is to thick flow nicely over the work, it ends up lumpy.

    Has anyone used the formula from this link for hand building.

    I notice that they have a bubble illiminator in the formula?

    Any suggestions would be helpful.
  2. There are bubble eliminators built into every commercially available epoxy. To get rid of bubbles there are a few things you can do:

    1) This is the most important. When mixing, don't introduce the bubbles to begin with. Most epoxies have a pot life of around 20 minutes or so. Mixing slowly for 2 minutes rather than agressively mixing for 30 seconds doesn't reduce pot life significantly and provides much better finishes. Mix gently with a smooth surfaced object (popsicle sticks are bad) like a drinking straw or back end of a paint brush.

    2) After mixing the epoxy, pour it onto a large sheet of aluminum foil. Spread it thinly over the entire surface. Take a drinking straw and blow on it lightly. You'll reduce the bubbles further.

    3) "Float" rather than brush the epoxy on. The brush tips are what introduce bubbles, keeping them out of the equation makes less bubbles. By float, I mean take enough epoxy that you're only applying the finish by the film between the brush and the thread, and that the brush never makes contact.

    4) DO NOT APPLY TOO MUCH EPOXY AT ONCE! Tin coats allow the bubbles to come to the surface where you can do something about it. Too thick a coat will make it hard for them to get free. Take your time, do a thin coat, and reapply a second. You'll like the results a heck of a lot more

    5) After application, use the same drinking straw and lightly blow on the wraps. That will further pop the bubbles in the finish.

    6) Finally, this is a completely overlooked thing. When you get to around 15 minutes on the finish, stop using it and make up another batch. After a while, the stuff starts to set, and makes it harder for the bubbles to migrate to the surface. Use a kitchen timer to let you know when your done. It's much less labor and time to blow a $1.50 of finish than to spend 2 hours wet sanding and reapplying finish.

    Finally realize there are lots of problems associated with bubbles, but a bit of dilligence and time will prevent them from happening.
  3. iagree
    A kitchen torch helps too, you the type used for making creme brulee. Jsut use a low flame and pass it QUICKLY over the epoxy. Not to much or it can catch fire, or get thin and run right off the rod. But it does burst bubbles VERY nicely and easily. Practice a bit to get the hang of it on a spare peice of rod or dowel with wraps on it.
  4. Please don't do this... I know it's kinda nice to do cause you feel like you're doing something (and you get to play with fire) but it's actually a bad thing. First off, you can scorch the mix very easily, introducing *more* bubbles. Second, the heat will cause it to set up quicker which will make any bubbles not popped unable to untrap themselves. Third, even if you do get rid of the bubbles, you can cause the finish to set up unevenly if you heat it unevenly. Considering the other tasks are easy to do and work just as well, I don't consider this an option.
  5. To each his own... I think the flame works well and haven't had any issues with it creating more bubbles. Besides if you really fouled it up up can always remove the flex coat with alcohol and try again. Its not the "playing with fire" part I like, its the smooth buble free finish with very little work.
  6. Oh well, I outlined a pretty good regemine for getting a bubble free, smooth surface. If you feel good about flaming go ahead, but people with more experience and time have moved from this techique due to the issues associated with it. For more info on the subject hit up www.rodbuilding.org. Also read up on the various manufacturer sites of the epoxy manufacturers. Ultimately it is about having the best finish, so do what's right for you.

    -- Cheers
    -- James
  7. Thanks James, I'm new to this rod building game and I do pretty much everything you outlined to, but haven't really considered that the flame might be a bad thing. I'll take it in stride and consider sparing the heat in my next build.
  8. Don't worry, I'm not saying you're wrong, I'm just trying to lead to a more consistant method of doing things. More often than not you'll be okay if you're sparing with the heat. But screw up once, and it's a hell of a lot of work to repair. Additionally, the lumpy finish problem isn't as noticable if you like thick epoxy, but if you like level thin finish like I do, those kinds of things are *immediately* apparent. Then again, I'm stupidly picky, so cavet emptor....

    Also, if you're a hobby builder, sure, it's not as big a deal. I'm not a *huge* builder, but the idea of wiping off several hours of work due to a mistake I could have avoided sucks. Also, the wiping off thing doesn't work if you're using color preserver. The alcohol will take off both the epoxy and CP, so you're basically left at ground zero, unless you want blotchy thread wrap colors.

    Finally, (just to let you know cause I was kinda harsh and I apologize), in the case of the Lamiglas factory they actually flame their FlexCoat. Then again, they have a assembly line where from thread wrap to epoxy is less than 30 minutes of time, plus a QA department that inspects and rejects substandard rods. I don't have that, so I have to be a bit more careful and discriminating in my initial efforts! :)
  9. Thanks,


    I think I am going to mix a bigger batch of epoxy as well. I am only talking a difference of a couple of CC. I like the straw idea along with the aluminum foil. I am getting down to the last thin coat.

    The reason I am so bummed about this bubble issue is that the Epoxy that I use for my kayaks are absolutely pristine for fine bubble free coatings. It is really thin in consistancy as well. System 3 SilverTip. It is verrry slow to go off though. So the big problem with this stuff is that the cure time is so slow that it allows a much longer time for dust to impact your finish. Maybe I should build a Class 1 Clean Room.

    Thanks again

  10. The thinner it is, and the longer it takes to cure, the more bubble free it will be. Super high flow things like water really let bubbles out quickly! Thicker cured epoxies don't. The faster it sets up, the thicker it gets, the more likely it is to trap bubbles.

    The dust thing was a real bugaboo for me for a long time. I did everything I could to try to speed up the drying of the epoxy. Radiant heat, heated electric blankets etc. Then I started getting the bubble issue. So finally I broke down and created a nice "clean" room for my work. Not hard to keep up, dust free, and I can just work at a reasonable pace. Realize it doesn't have to be completely sterile, just dust free. Another thing to keep dust to a minimum is to consider a drying box. A bunch of old plywood, and some stands, and you just close and open to turn it. Keeps the dust way down and it's cheap.
  11. Other things to consider:

    Consider using a small artist's spatula instead of a brush to apply finish.
    Make sure you are not applying too much tension to the thread and creating "fuzzies" on your wrap.
    I simply use a 100 watt light bulb held a few inches away from the finish to get rid of bubbles.
  12. I am using a simple dry box tonight. Just built it out of 10 mil visqueen and plywood. I mixed slower, and poured my mix out on some foil. It was still hard to brush or float the stuff out on the rod still thicker that I want it. I also used a drink straw to blow on the material after applied. I blew on the puddle of material on the foil prior to application as well. I could see the bubbles coming up. Cool. I may try the SilverTip resin on my next rod. Now I have justification for another rod to build right?

    I will post some photo's when I get a little farther along. I am building my 4th rod up from a Dan Craft Blank. I am getting addicted to those things. They are about the straightest blanks I have ever seen. This one is a 2 Wt.


  13. The thickness thing is kinda easy to deal with.... After applying the finish, let it sit for 30 seconds or so in one spot. You'll see some epoxy sag, take a clean brush or spatula, and pull off the excess. After that, just put it on the dryer.
  14. What I do is mix my epoxy in a small plastic cup and then put that cup in a cup of tap very warm/mildly hot water tap water. It makes the pot life a little shorter, but it helps the epoxy to be a little warmer and help get rid of air bubbles. It has worked well for me for quite a while.

    Also, getting rid of my flex coat and gudebrod epoxies and using threadmaster has been a really big help as well.
  15. Here is a quick fix..ditch the Flex Coat and give the new Threadmaster a try! Its great and it flows on the wraps like the wine of Capostrana! Its much clearer that Flex Coat too.
  16. I would suggest that you either keep the epoxy in your pocket while you're getting other stuff ready (before you mix it). Or you can get one of those coffee cup heaters and keep some heated water in your work space. This will help keep the epoxt thin, it's really helped keep bubbles out of my wraps.
  17. Once again, the application of heat can exacerbate the problem with bubbles. The more it's heated the faster it will set. While it's nice to start out with, reducing pot life is the exact opposite of what you want. Epoxy temps around 70-75 degrees are what these things are made for, and keeping close to this is one of the best things you can do.
  18. Many of the things James speaks of I learned the hard way 30 years ago. As a result, I will never use heat on epoxy rod finish. Any of the major 2-part rod finishes produce a good, smooth finish; however, the light versions are less prone to produce bubbles and work better on fly rods because they require 2-coats to make a good finish.

    This said, I have a decided preference for Frondak's U40 LS Supreme (which is made in Monroe, WA) since I started using it because it has fewer bubbles than Flex Coat (which I used for nearly 30 years). Threadmaster is rapidly gaining a following, but I've not used it.

    The biggest thing you can do to get a nice bubble free finish is use one of the light 2-part finishes and pour it out on aluminum foil (I use an old pie pan covered in foil for this, but any shallow, fairly wide container covered in foil can be used. Heck, even a paper plate covered with foil works fine). Then let it sit on the foil for 1 or 2 minutes before you start applying it.

    You could also forgo the 2-part finishes completely and use Trondak's U40 one-part finish. Granted it takes 4-5 coats to get a good finish that covers all the thread completely, but it produces a great finish without bubbles because it is as thin as varnish. The downside, once you open the bottle, it will only last a few weeks before it solidifies in the bottle because it cures from the nitrogen in the air.
  19. Actually it's a moisture cure urethane.... People in Arizona have little idea how fast it really cures, as they don't know what it's like to keep it here... Last bottle I had lasted around 2 weeks before it was hard junk!
  20. Thanks for the correction on what cures the U40 one-part finish James.

    I really like the finish it produces because it looks a lot like a finely fiinished, varnished cane rod complete with a great depth to the finish the 2-part finishes don't give you. The downside is it requires about 5-6 coats applied over 5 days to get the really wonderful finish you can with it. Then you have to wait about another 4 days before you go fishing with the rod to be sure it is completely cured. But like you, I found it doesn't last very long after the bottle is opened; therefore, I view it as one rod per bottle.

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