Experienced With Ecopoxy Liquid Plastic?

[Mike Ontko]

For anyone who may have particular experience using Ecopoxy's Liquid Plastic (1:1 ratio), have you ever encountered a situation in which your mixed and poured batch didn't cure completely, and if so what did you do? No, I haven't reached out to the manufacturer yet, because I fear that I'll get the answer I don't want to hear.

I was careful with the mix ratio and the mixing process. The temperatures were somewhat below the optimal 72-degree range, but close enough that there shouldn't have been an issue. But in general here's what seems to have happened...

The pour, made in two steps, was intended to fill a void created by routing out a design into a 1-1/2" thick western cedar sign, made by spline joining several 2x6 boards together. The first step was to route out the design onto one side of the sign to a depth of approximately 5/8", and then fill that void to the top with Ecopoxy Liquid Plastic resin (approximately 2-Liters). Everything went pretty well for that portion, except perhaps the cure didn't turn out to be as solid as I was expecting after waiting nearly 3-weeks. For the second step, I flipped the sign over and routed out a cavity behind the initial routing, now containing the cured first pour, then mixed up and poured approximately 1-Liter of the resin to a depth of just under 1/4". The end result: the second pour never completely cured, it's slightly tacky to the touch and gives like a semi-solid gel. What's worse, however, is that the original pour seems to have softened.

I suspect one of two things, assuming (yes, I know about that word) that my mix ratio of hardener to resin was good and the mixing was thorough. Either the temperature needed for initiating a proper curing process was never achieved (Ecopoxy's own instructions caution against pouring to a depth less than 1/4" because too little material can't generate the thermal change needed to initiate a full cure...something I didn't learn until after I'd completed the pour). Or possibly, I was using an old batch that had stability issues to begin with.

What I'm wondering is, can I add an additional pour on top of the second semi-cured pour in hopes that the hole thing might somehow work out? Or, am I just going to have to face facts and scrap the work and go back to the drawing board?

Thanks in advance for your input.

[Steve Kang]

Are you sure the mix ratio was supposed to be 1:1? I recently used the ecopoxy liquid plastic product and the ratio I used was 2:1. I believe at some point they changed their guidance on the ratio mix...

[Don Peters]

Pouring more material over the top won't fix it. It may make it worse: hardened material on top of uncured substrate. Assuming your ratio was correct, the only fix is to elevate the temperature significantly in an attempt to encourage a cure. This has a decent chance of working, especially if you can bring the temp up above 100º F. However, it may take a long time.... like weeks.

[Mike Ontko]

Are you sure the mix ratio was supposed to be 1:1? I recently used the ecopoxy liquid plastic product and the ratio I used was 2:1. I believe at some point they changed their guidance on the ratio mix...

Yep, that was my first thought as well. But the instructions on the box indicated a 1:1 ratio. One thing I didn't mention before is that the container of resid had a pretty considerable lump in it that I thought might have been a crystalization from sitting on the shelf for a long time, or possibly being exposed to wide temperature changes from the time it left the factory till I used it. The first batch was like that as well but the crystalization wasn't as significant, so I just used a heat gun and a lot of pre-stirring two work out that crystalization or sedimentation. With the second batch, that crystalization seemed too far along and I wasn't even able to squeeze it out of the bottle. So, it's definitely possible that the resin wasn't right to begin with.

[Mike Ontko]

Assuming your ratio was correct, the only fix is to elevate the temperature significantly in an attempt to encourage a cure. This has a decent chance of working, especially if you can bring the temp up above 100º F. However, it may take a long time.... like weeks.

It's been sitting in my garage/shop for almost three months now, with temperatures ranging from the upper 60's to 90's (the garage can gets pretty stuffy if I don't open up the doors). At first, I had tried shining two 500 Watt halogen work lights on it. The image is almost 43 inches in length by about 20 inches in height, so it's a little difficult to heat evenly. I even tried installing the LED lighting and the placed a section of plywood over it to trap any heat. I let that sit for a couple of days but the LEDs run cool and I don't think the temp ever went above 80F.

But the manufacturer recommends the same general approach of applying heat to help get the curing process going. Something else I did for the first pour was to preheat the resin (mainly to get the lumps and grainy texture out) using a heat gun while stirring. I wasn't that careful with the second pour mainly because the garage was already warmer than when I did the first pour and the resin was already flowing well.

I can attempt to apply a little more direct heat and see if that has any effect. I think though that I may end up chalking this one up as a costly learning opportunity, and just scrap the whole thing (about $500 worth of materials--argh!).

The pic below shows the sign from the back side with the LED strip partially installed. Eventually, this was to be covered with a white enamel or melamine covered section so that the LEDs don't necessarily need to be on in order to see the image from the front (the angle iron is inset and epoxied in place at the ends to keep the whole thing from potentially warping over time).

After second pour.jpg

[Frank Pratt]

(the angle iron is inset and epoxied in place to keep the whole thing from potentially warping over time).

What a shame. That's a very cool looking sign. But I think you'll want to reconsider the angle iron brace. With it solidly screwed & glued in place, there will probably be cracking or, ironically, warping due to the wood moving with humidity changes & the iron not wanting to let it. The wood is going to win that fight. Better to drill elongated holes in the iron to allow the wood to expand & contract like it will want to do.

[Mike Ontko]

What a shame. That's a very cool looking sign. But I think you'll want to reconsider the angle iron brace. With it solidly screwed & glued in place, there will probably be cracking or, ironically, warping due to the wood moving with humidity changes & the iron not wanting to let it. The wood is going to win that fight. Better to drill elongated holes in the iron to allow the wood to expand & contract like it will want to do.

Right you are, Frank! The epoxy in this case was only applied at the ends, and the screw holes were extended to some extent (I'm also expecting some amount of shrinkage after this begins to get exposed to full sunlight). The boards are all splined and glued together as well using Gorilla polyurethane adhesive.

And in all honesty, there were at least two comments from folks on this board recommending foam board. But I'd already had it in my head to go with natural cedar since there's a also black powder coated steel sign that will be mounted on the front side, just slightly below the mountainscape image.

[Corey Pelton]

No matter the temp of my shop, I always sit the containers in some warm water for 10-15 minutes. Ecopoxy loves to crystallize and clump, like you mentioned. You’ll get bad results if it’s mixed with any crystallization. I also use infrared warmers with reflectors to help with curing time and clarity. Works like a charm.

Liquid plastic is definitely 2:1 ratio, so maybe you have one of their other offerings?