Charles

Paint/clearcoat Blistering and peeling.

19 posts in this topic

Charles    10

On my last fishing trip (in tropical heat) I had several of my Top water baits blister and fail.

I use Paulownia and its very grainy and so the process is as follows:

Sanding sealer from zisner (sp?) from home depot 2 coats sanding in between and let dry over night. Dipped

Then I use Sherman Williams (automotive) sanding primer dipped in can, let dry sand and coat with a white SW sprayed for base coat. Then follow with sw paints. All paints are SW automotive paints.Their replacment to acylic laquer.

I then top coat with Etex light.

Some lures failed all the way to the bare wood others to the sanding primer. The Etex peels right off. There was more than 2 weeks from the time the Etex was applied untill they were used. All failed before they touched the water but where stored in tackle box in direct sunlight.

I have never had this problem before.Wood was dry.

Iam suspecting the sanding sealer as not being able to handle the heat.

90deg F, maybe more in a tackle box on the floor of an aluminum boat.

I am back to the drawing board and am researching a better process

and would very much appreciate any advice, constructive/destructive critizism ect:teef: Spent the last 2 days researching the Forum and only caught a couple of threads that touched on the subject (blistering).

1 thread stated sealing the wood to prevent blistering and 1 that suggested etex might not hold well in the heat.

I am ordering some DN lure coat to try and maybe some of the paints.

But what I need is a good sealer to level the grain and I am researching the epoxy sealers.

Thanks,

Charles

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hazmail    137

I recently had the same experience with a 'Mylar' finish- the top coat lifting off, and heat was also a factor. I made them in a hurry and I think it was the glue I used, still gassing off.

This vapor would build up quite a bit of pressure and something has to give. Depending on the base coat etc, you could finish up with a paint scheme 1/16" thick, which is a lot of paint thinners to 'gas off'. Dipping in primer would not help (although effective) as the coating is vastly thicker than when sprayed, and sealer /primers usually have a high solids content, which all adds to the thickness and time required to DRY.

Saying all this, most lure manufacturers (here) warn of not leaving wood or plastic lures in the sun, especially darker colors. I have had 'flatfish' (plastic) and others, double in size on a hot day, just from heat and air expansion in the lure, and these were on the floor of my boat. I think any lure will blister, given enough heat/sunlight - I now glue a sheet of white paper on top of my clear lure boxes these days, seem's to help. Maybe water based primers/ fillers would help.pete

8 DAYS TO LIFT OFF, CLINTON

Edited by hazmail

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rjbass    1

I believe your Zinsser sanding sealer is Shellac based if I am not mistaken. If it is the same stuff I am thinking of, that is your culprit. For whatever reason it does not do well with epoxy. Try minwax sanding sealer, great stuff.

Rod

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mark poulson    1,680

I've had that problem only with lures I've use rattle can paints on under the Etex. I think the solvents are still there, and the heat vaporizes them. Also, one of the main culprits in clear coat failure on residential woodwork, like when you have a door or window, and stain the exterior and clear coat it, is that the UV from the sunlight passes through the clear coat, and attacks and breaks down the bond between the wood and the clear coat. The expansion and contraction of the wood causes micro cracks in the clear finish, and eventually water gets in, and the rest is history.

I don't think micro cracks in the clear coat epoxy finish are an issue hear, but the heat and UV action on the solvent based paints is probably the culprit.

I've used Krylon solvent based primer, and then Createx water based paints, and not had any issues. I've also used pastel fixative over the Createx after I scale, before I add other layers of Createx, and not had a problem. Same deal for a final coat of glitter in a solvent based carrier.

For me, it seems to be only if the actual paint is solvent based, and multi-layered, so there is a lot of residual solvent trapped beneath the layers.

At least, that's my story, and I'm sticking to it.

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rofish    2

Charles,

Being on the other side of the world, I do not know anything about the materials you are talking about - sealer, paint, epoxy.

But physics is the same everywhere.

First, your lures are made out of paulownia wood, which, being so light, has much more air trapped into the wood. This air will expand because of the heat, pressing on whatever will block its way out.

A solution to this problem would be that you use denser wood. If you still want to use paulownia wood, and want your lures to withstand higher temperatures, then a good idea would be that you heat the blank of the lure before applying the sealer. This way, you seal the lure with thinned air in the wood, so the difference in air pressure will be less if you put the lure in high temperature. Depending on the sealer, you could heat the blank before applying the second layer of sealer as well (and even before the third one).

You do not have to worry if you fish such lures in cold water,because in this case the air inside the wood shrinks, but it cannot suck the paint or epoxy inside the lure, because all these layers lean on the wood, which is strong.

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mark poulson    1,680

Great idea!

Pre heat the blank before it's sealed.

Makes perfect sense for eliminating any problems caused by air expansion in wood.

I use Minwax Polyacrylic as a sealer, dipping my lures, and plan to try that next time.

Thanks.

Edited by mark poulson

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rofish    2

Mark, I do heat the blanks in the oven before sealing them in propionate solution. But I also put them back in the oven after the surface has completely dried (15 - 20 min). You can see blisters of propionate solution or even small springs of solution coming out of the lure. If I would not do so, I think I would just replace the air with solvent based sealer, and since the inside solution cannot dry, because the surface is sealed with dried solution, the only way to dry this inside solution is heat. I am aware of the danger of an explosion, so I do not recommend heating the lures the way I do.

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mark poulson    1,680

rofish,

I use Minwax Polyacrylic as a sealer, and it's waterbased, so I don't think I'll have explosion problems. What I thought of after I posted the first time is the sealer may dry too quickly on a warm lure blank, and not bond as well.

I'll try it with a scrap piece of wood first.

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rofish    2

Mark, do you use that Minwax stuff to dip your lures in? If so, you will not have the temperature problems that you mentioned, because the lure will start cooling the moment you dip the lure in. Depending on how thick the Minwax is, the lure will suck in the stuff more or less. The problem is how do you cure this sealer if it goes into the wood, so not merely on the surface of the lure. Heat does this for the propionate solution. But for the that Minwax stuff I don't know.

The whole idea here is to seal the wood while it is warm. But when after the first dip into a thin solution I also heat the lure so that the "inside" solution will cure, I know that I may have not sealed the wood properly, so after cooling, it may suck in air again. That is why I seal this way the wood twice or even three times.

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mark poulson    1,680

rofish,

This is starting to sound like real work. :huh:

I'll seal it once warm, scuff up the coat when it dries, and then seal it again without reheating it.

I only make lures for myself and my friends, and, knock on wood, so far the only lure I had bubble was one that I had painted with rattle cans, and then Etexed.

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rofish    2

I also make lures just for myself and friends.

The necessary coats for sealing depend on how thick the sealer is. I dip twice or tree times the lures taken out from the oven (almost hot), then another 4 coats, this time at room temperature.

But if you use a stronger material, such as thinned Devcon 2 ton, I think that just one layer would be enough for the sealing.

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Charles    10

Thanks for all the advice.

I am inthe process of changing sealers and I plan on heating the blanks

before I seal.

I just tried fiberglass resin (just to try) to seal the wood and I let it set then sanded and painted plain base coat and applied Etex and let it set for 1 day and a half.

I put the blow dryer to it and it blistered but I think more a problem with etex than from the lure gassing out. But I wasnt sure how hot I got it either.

This next round I am going to use a insulated box and a thermometer to try.

Thanks for the input..........

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Charles    10

Thanks for all the advice.

I am inthe process of changing sealers and I plan on heating the blanks

before I seal.

I just tried fiberglass resin (just to try) to seal the wood and I let it set then sanded and painted plain base coat and applied Etex and let it set for 1 day and a half.

I put the blow dryer to it and it blistered but I think more a problem with etex than from the lure gassing out. But I wasnt sure how hot I got it either.

This next round I am going to use a insulated box and a thermometer to try.

Thanks for the input..........

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Vodkaman    888

I used the polyester resin as a sealer coat too. I thought it was very good. It added a lot of strength to the balsa an gave a hard surface for final filling and sanding. Someone posted last week that the resin is not water proof. This came as quite a shock to me and could be worth some further research to confirm (no disrespect to the member who posted).

As for possible reactions with subsequent applications, I cannot help, but after 24 hours, the chemical reaction is complete and the result should be fairly inert, but chemistry was not my favorite subject.

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mark poulson    1,680

Charles,

Did you use water based paint and a hair dryer to heat set you paint before you coated it, or did you use solvent based paint?

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rjbass    1

You guys are reading way more into this than there is.....keep it simple....there is no need to head the blanks....I have been making baits for years, never heated anything except for my shop....

Rod

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BobP    805

I'm with RJ on this one; most coatings are engineered to work at room temperature. Speeding up the outgasing of solvents isn't always good for the formation of a durable film and a lot of things can go wrong in the meantime. Whenever I've experimented with baking or heating solvent based finishes, it has been a fiasco. So I try to keep it simple. All I use are propionate/acetone, epoxy, acrylic latex and Dick Nite polyurethane. They generally mix and match fine, harden OK at garage temps, and are durable when cured. The only heat I use is to flash dry acrylic paint with a hair dryer when airbrushing. And that's just so I don't have to stand around watching paint dry. I'm not a fan of many solvent based coatings. They're toxic and often incompatible. Lastly, some of them smell bad even after they've dried. I hate to open a tackle box and smell solvent stink on crankbaits I'm getting ready to fish with.

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