Propionate Seal/ 2-part Finish Dilemma

[buffingtonwa]

I'm experimenting with different 2-part epoxies.  Recently, I dipped a bait, 5 times into propionate to seal it, allowed to dry each time, the waited a couple of days before I got around to priming.  I primed the bait with a white primer (auto-air) then I mixed up an batch of Eager Plastics Crystal Clear 202, an experimental 2-part epoxy I'm trying out.  Anyway, I measured the 2 parts by volume on a scale, mixed it up, applied the mix to the lure with a plastic bristle brush and then put the lure on a turner.  After the first application, there appeared to be significant shrinkage, but I noticed that there were some areas that were still sticky and others that were completely cured.  

 

Just messing around, after I got finished applying to the primed bait, I took a little of what was left over and applied it to a bait that had only been dipped in propionate.  The propionate only bait, after adequate cure time was still completely sticky all over.

 

At first, I thought maybe I didn't mix it up enough, but since some of the baits was hard (and all of the remaining epoxy in my mixing cup hardened), I don't think that was the case.  I also thought it could be some surface contamination, but because the bait just sealed with propionate and finished with the 202 didn't cure at all, I'm thinking there is some kind of compatibility issue with the 2, or maybe some solvents in the 202 or leftover acetone in the prop that could be causing the problem.  A second application of the 202 on the same bait produced the exact same results.

 

This was my first trial doing this, and a possible solution may just be to clearcoat the bait before adding the finish.  But I wanted to send out a forum and see if anyone had any other insight that might help.

 

Thanks. 

 

[RayburnGuy]

The epoxies I've used all call for mixing in equal amounts by volume. The epoxy and hardener have different densities and don't weigh the same when measured in equal amounts. I don't use propionate so not sure if this is the exact cause of the problems your having, but it's possible it could be a contributing factor.

 

Ben

[defish]

I agree with Ben, all epoxies that I'm familiar with are to be measured by volume NOT weight.  I like veternary syringes to measure each epoxy part with, and a lot of people use disposable plastic medicine measuring cups for larger amounts.

 

With part of the bait dry and part sticky it does sound like the finish also needs to be mixed a bit more.

 

Good luck.  It sounds like some interesting stuff being "UV Resistant and Not Brittle."  Give mixing it differently a try and let us know how you like it.

[buffingtonwa]

The company specified a 100:90 ratio by weight in the paperwork sent with the epoxy, so that's the way I did it (typo above).  I would agree that the epoxy needs to be mixed more, except that the stuff in the mixing cup all cured very hard without being sticky, and I also applied a second coat just to be sure and it came out the same way.  On further inspection is seems to be reacting with the primer.  The primer appears to be gooey today, so that's probably what happened.  I guess a coat or two of clearcoat may be necessary before applying it.

 

*Note:  If anyone is thinking of trying this stuff out, it's very thin so multiple coats will most likely be necessary.  Eager plastics looks like they have some good products and I'm sure I will be experimenting with more in the future.  

[EdL]

http://www.eagerplastics.com/cc.htm

 

This web page info suggest 1:1 mix volume or weight for CC 200 series. 

Could this be the problem?   Just guessing.  MIght check with manufacturer to be sure.  Maybe they changed something and the paper work is correct while web site is not.  You also may be right with primer interaction.  Good luck figure it out.

Edited January 22, 2013 by EdL

[RayburnGuy]

I just read the page at the link Ed provided and if this is the same stuff your using then it is not epoxy. It's a urethane casting resin. That's why I was thinking that either improper mixing or the wrong amounts of epoxy and catalyst were what were causing your problems. Epoxy is pretty predictable and forgiving in the reasons it doesn't set up correctly as well as having small allowances in the volume of each part. Epoxy is also fairly inert in that it doesn't chemically react with other components.

 

I can't help you much with the urethane casting resins as I personally have no experience with them. I do know that urethane top coats are notorious for having bad reactions with other materials that have solvents in them. The different solvents may not play nice together and when they don't you can have experiences like the one your having. More than one paint job has been ruined by using paint with one type of solvent in it and then using an MCU (moisture cured urethane) for the top coat.

 

I would suggest that you try sealing a lure with either the casting resin your using or a 2 part epoxy like D2T or Bob Smith Epoxy and after it cures do your paint job. After the paint dries apply your casting resin as a top coat. If there are no problems then the propionate and casting resin are reacting to each other.

 

Ben

Edited January 22, 2013 by RayburnGuy

[hazmail]

Also make sure the Prop is cured - The prop I have used (disolved in lacquer thinners) takes weeks to cure right through, especially 5 coats --sniff it, if you can smell it, it's still cureing, so the solvent gassing off will probably effect the top coat.

 

This solvent has to escape somewhere so it makes small 'windows' in the epoxy ("fisheyes") and also would probably dilute the epoxy on the way through maybe wrecking the chemistry of the top coating.

Just another thing to check mate.

Pete

Edited January 22, 2013 by hazmail