Air pockets in foam baits
19 replies to this topic
Posted 17 February 2008 - 01:24 PM
Hello to all, need some advice or a solution. Casted some foammies, sealed the profiles, pretested, then decided to go ahead and paint up and clear coat with Devcon. Had good results, and prototypes ran good in the water with no indication of problems. Decided to go with design and casted up about a dozen and finished all for me to use this weekend at a local tournement. Water temp was 49-52 degress and after 8 hours of pounding the bank noticed that all the foammies were having air pockets starting to develop under the paint. Man what a failure I thought, but the baits actually caught fish. The failure didnt happen until later in the day. I think someone here mentioned that foam baits is bad to degas. Is there anyway to get around this problem with 16lb foam? I like the foam material but cant afford to have these air pockets formming under the finish. Any adivice here will be appreciated. I do have some Urethane Resign material with micro balls ready to go but I just started out with the foammies. Can you heat treat the foammies to get the air pockets to escape before finishing?
Posted 17 February 2008 - 03:10 PM
How long did you wait before painting/finishing? You might have not given the air time to escape before you finished them. I don't think that heat treating them would be such a good idea if you did'nt heat cure them. One thing that you could do to find out if you have air trying to escape is to take a recently poured and cured bait and submerging it in water and see how many bubbles come to the surface and then compare it to another raw bait that is a week old or so and see if there is a differance. Thats all I can think of but i'm sure someone that is more knowlegable than me on this subject will chim in.
Posted 17 February 2008 - 03:58 PM
At least a week had passed by before I started the finishing processes. I am really baffled into what caused this issue. I will be contacting the distributor about this to see if they can suggest a way to keep this from happening.
Posted 17 February 2008 - 04:33 PM
Sounds a bit wacky I know, but maybe the water temperature is greater than the air temp, causing the air to expand in the lure, lifting the coating. Also consider the atmosphere and temp that the lure was originally sealed in- was it very cold/ humid etc. I have never made 'foamies', but with the heat extremes here (-5c winter to 40c summer) it is sometimes a problem with wood as well, especially balsa. The top coat may be a problem also, DN is tough and relative to D2T is soft/pliable and takes a long time to cure, I have never used some of the rod finishing type top coats on lures, but they are soft/pliable as well. Whatever, it seems to be expansion/ contraction, the old suck and blow problem. Have a look at your primer, peel the blister off, is it bonding to the foam properly? Hope this is of some help. pete
Posted 17 February 2008 - 04:50 PM
Had the same problem a few years ago before they even hit the water. I made up a few for a charity lure auction and spent hours painting and putting special logos on them. Was walking out the door to the auction,picked up the lures, and they had blisters under the e-tex. They took a last ride into a block wall and that was the last of my 16# foam days. Funny thing was that I had done several others before with no problem and the same curing times.
Posted 17 February 2008 - 07:27 PM
It sound to me that every time you make a special effort, the problem occurs. The prototypes worked fine, then you made a dozen to use in a comp, problem. Then you made a bunch for charity, problem.
Every casting is going to have some flash type deformation at the mold joint and will require a certain amount of finishing. My guess is that in your attempt at preparing for the best finish possible, you are removing too much material from the raw casting and clipping the top off some of the bubbles.
The bubble fractures are not large enough to allow the primer coat into the bubble void, thus preserving a weakly contained bubble of air. Once in service, any direct sunlight will be soaked up by your colors and the air bubble expands.
The solution is to address the problem. Remove as little material post casting as you can get away with. Still assume that some of the bubbles have been compromised and seal accordingly. A very thin sealer with a low viscosity would probably be favourite, maybe propionate. Maybe heating the casting in a low oven for five minutes before applying the sealer would help by expanding the air. As the air contracts with the sealer application, the sealer will be drawn in. I'm not convincing myself on this one, warming the sealer might help too (no open flames!!!).
Before moving onto the next phase, why not test the results under a 50W bulb for 30 minutes. If the problem exists, this should reveal it.
I have only the briefest of experience with foam, so the above is not from personal trials, just common sense and engineering. I will bow to experience here, should it conflict with the above, as I too need a solution to this problem, as I am thinking of going over to foam myself.
Posted 17 February 2008 - 07:47 PM
I wonder if the existing baits can be saved? I know when surfaces bubbles, using an insulin syringe with glue or epoxy in the bubble provides a place for the gas to go and the glue or epoxy seals the gap. I just hate to hours of work get trashed.
In this situation, maybe a pin hole to allow the bubble to completely finish out gassing for a week or two, then seal them with glue or epoxy, working the bubbles smooth. It might be worth a try.
Posted 17 February 2008 - 10:25 PM
Was there any prep. done on the foam?
What type of sealer if any was used?
What type of primer is used?
Did you use foil?
What type of paint or paints were used?
If you used different paints, what order were they applied in?
What did you topcoat with?
I have never worked with foam but I think these questions might reduce some of the guesses at what went wrong. To me it sounds like layers on top of layers that never bonded but that is just a guess.
Posted 18 February 2008 - 05:24 PM
This same thing happened to me last weekend,I used Krylon fusion,Rustolium neons,and sealed with D2T.
Between coats...I cleaned lures with denatured alcohol.
Posted 18 February 2008 - 07:35 PM
Hey folks thanks for all the suggestions. Brief history into construction method. I use a lamination process, two sides laminated together to construct the bait. I used a rtv mold, casted the foam and waited aprox. 35-45mins demold time. Pulled out, set aside for almost a week in an unlaminated state, Just two sides laying there. Put two sides together and tempoary glued with instant glue. Finished shapping and contouring the small edge that is left around my baits after demold to get smooth. Then sealed with fiberglass resin. Sanded smooth, After resin dried, sprayed 2 coats of gray automotive primer out of can, fast dry Rustoleume product. At this point nothing was showing any ill effect. Sanded again and everything was looking flat and even. Went to the createx paints and sprayed my colors, at this point I heat set paint with heat gun like I always do,no problems yet. Assembled lexan lip, eyes, and off they went to the drying wheel. Sealed with one coat of D2T because of the time I had before the tournment. About 24Hrs at 50-65 degress air dry temp for the Devcon two seal. Air temp Saturday was 44 degrees and got up to 64 degrees and water temp was 48 and I found 53 degree water later in the day. Noticed puffy spot under epoxy just in one of the baits and just said thats a wasted perfect fire tiger paint job. Saw that little virus first thing in the morning and that plug had not even hit the water. Just wrote it off as oh well have alot more to throw. Caught one on first cast with Chart.Yellow/Brown fish scaled, pattern sides and back /with Flours. orng belly. Noticed latter in day that plug started having raised puffy spots also. Then I was ill with the virus. Noticed the majority was having this problem. At this point I decided to totally write off the foammies and move into the UR with the micros spheres and not mess with the foammies at all. Then decided to speak to you all and see if there is a solution for this. Thats the history so far.
Posted 18 February 2008 - 07:47 PM
Palmetto its two soft, almost like the hardness of the lure had changed from rock solid, to almost like a plastic coke bottle feel with the spring back one pressed upon. I would say its not in the epxoy finish, or the createx, paint, or in the primer, Could be a reaction between the resin of fiberglass to instant glue to the urethane foam. I cant belive the cooked chemical state could change its hardness this blows my mind.
Posted 19 February 2008 - 12:30 AM
What brand of foam are you using... Im just curious so I never try it.. cause it sounds like a pain in the butt!! Let us know if you get it fixed..
Posted 19 February 2008 - 01:07 AM
I would not give up just yet. You need to do some tests to find out what the problem was. Cast a few more and coat with the resin. When cured, put them out in the sun. Put an uncoated casting out too, for comparison. It could, as you suggested, be an adverse reaction. You are playing with a very complex chemistry set, the sun's UV is another reactive component.
Try a different sealer!
By giving up to move to resin, you are making me nervous, as I am about to make the move in the opposite direction! You have already invested plenty of money in the foam, you might as well follow through. By all means, build some resin baits, but do the foam tests. Then you can compare the pro's and con's of both materials.
Posted 19 February 2008 - 01:37 AM
I have been currently using 16lb foam for my swimbaits and had a reaction similar to what happened to Rossrods. but only on the one bait i primed with bulldog plastic primer. I have experimented with bulldog , fusion and rust-o-leum plastic primer and I have had my best results with the rust-o-leum Plastic Primer it drys matte not semigloss like fusion more bite for my creatix coats I also let my paint cure for a week before I devcon 2 them I personally believe that with acrylic paints you should wait and let them get good and hard before you topcoat I do not think What is happening to rossrods is the foam softening but the paint pulling from the bait off of his primer that will make it seem like it feels like a coke bottle, it did the same on mine. the foam under the paint and topcoat were intact.
Posted 19 February 2008 - 05:51 AM
I would be looking at the fiberglass resin as the main culprit. Since you mentioned the bait was soft we know a reaction has occured and with most "foams" solvents are going to be your culprit. I will assume youre bait was sealed by the fiberglass resin so the rustoleum product would have no effect. I always stay away from solvent (non water based) products with foamies or take the time (gulp slow down on making a bait) to make sure that it is really dry. You might be surprised to see how long it can take to really dry some products especially when we start to layer. Take a look at the organic solvents contained in the products you used and then look at the compatibility with the 16 lb foam and you will likely find the answer to your problems.
Posted 19 February 2008 - 05:56 AM
it's happening along the joint ? maybe the pressure is causing the air caught between the two halves to Plaster of Paris out ... just a suggestion...even so the air can travel underneath the primer to a certain point
I'm preparing to try some foam tests , but I'll try a one piece mold ... hope I wont run into the same problem, I'll use propionate+acetone mix vs lacquer as primers
Posted 19 February 2008 - 04:57 PM
Update to all. I will bow down to the Urethane foam and have to be a man, and not a mouse, and admit that I was to quick to jump to conclusions. The foam had no reaction with any of the glues/resins/or the primer. The foam had no problems. The problem occured from the D2T pulling away from the primer coat. I have been building baits for almost 3 years and never have had a issue like this before. The castings and foammies is something new so I was quick to point failure at something new. On one hand I am relived to know that the lessons learned here are sometimes hard earn but very much worth it. So in conclusion to this, the foam baits did very well. It was the epoxy pulling loose from the primer coat. So I will say to all who wants to learn how to use foam keep on and dont give up. To all I appreciate your inputs and next time I will not use the D2T below 60 degrees this is probally were I made my mistake. How I found the solution was dissected one of my air pockets and found everything still intact underneath the primer/resin/instant glue/and down to the foam. So had failure either at the createx or the D2T. I heat set the createx so I would be more willing to lean towards the epoxy being the culprit here because I applied below 70 degrees. I have noticed alot of flaky things during cold weather popping up about our beloved clear coat finishes be applied at this present time. I wonder if anyone in the tropical or warmer climates have had any issues as above. So to all I will go now and EAT MY CHEESE. lol
Posted 19 February 2008 - 06:16 PM
how long of a wait did you have between primer and painting?
it is very possible that the primer hadn't fully cured thus adding to your troubles.
Now about eating some cheese that thought scares the heck out of me!!! what kind of canibal are you?
Posted 19 February 2008 - 06:26 PM
Good one their my cheese friend, look out I watched Mr Brooks the other night.LOL. I would say at least 24 hours and for some of this time they were heat set with a quartz halogen light about 2' away which keeps my temp around 70-80 in my crankbait dungeon for about 2 hours. I sprayed my createx at about 60degrees this could be the problem
Posted 19 February 2008 - 07:32 PM
I am relieved to hear this, as I think polyester resin makes a great sealer coat. Very strong, smooth and it seems to accept paint well, although I don't do much there, other than applying some white for visibility.