Managed to ruin a project - time for a re-do

Projects
1

I wrote everyone a couple days ago about my experience using different bits on my “Built Ford Tough” sign.

Well… after a few tries, I got acceptable results on the x-carve and it made a real nice sign. Unfortunately, I got carried away trying to fancy it up with the finish, and the result is very bad indeed. I thought I would share my result with everyone here, and maybe pick up some pointers from anyone who has been down this road.

Here’s what my sign looked like straight off of the x-carve:

IMG_1351.JPG480×640 93.9 KB

After I sanded it up, I hit it with some dewaxed Shellac (2 coats) as a sealer. Again, here’s what it looked like:

IMG_1353.JPG480×640 101 KB

So far, so good. I had originally planned to stop there, but then I got the wild idea to use a self-leveling epoxy to try to give it a “filled with glass” effect… bad idea.

I used a product called “Famowood Glaze Coat”, which I had seen some youtube videos on with real nice results. The instructions were pretty clear: pour out equal parts of the 2-part epoxy, combine and stir for 6 minutes, transfer into a new pail and stir another 6 minutes. Then pour over your project and apply heat (I used a heat gun) for up to 15 minutes to remove bubbles. After that, cover and leave for 24 hours.

When I got done pouring, I was really encouraged. The bubbles were easy to blow away with the heat gun and it had a glass smooth finish.

It’s hard to see from the pictures, but the epoxy really made the depth stand out.

IMG_1379.JPG480×640 93.1 KB

This is basically what it looked like when I covered it. Unfortunately, when I came back about 5 hours later to check on it, the story had changed significantly:

IMG_1383.JPG480×640 115 KB

As you can see, the entire bottom left side of the sign picked up a huge amount of bubbles that by that point were locked in to the tacky resin. The project is essentially ruined.

Has anyone worked with epoxy before in this way? Did I do something wrong by applying a Shellac sealer? Did the plywood “off gas” something in that area that allowed all those bubbles? Where did I mess up?

Being stubborn, I have the mind to try this again and see what happens. The thing looked so good before all those bubbles came up…

1 Like
2

You need a heat gun to heat the epoxy after you apply it. This will cause all the bubbles to raise to the top and go away.

1 Like
3

Two thick layers of wood hardener helps before epoxy. No air bubble comes out of wood. But must be dry for 12 hours.

4

I’m interested to see if you can pinpoint the cause, I haven’t used it but am interested in seeing how well it works. Or doesn’t.

Can I suggest trying again on a simple pocket, rather than testing on another complete sign? :smile:

5

I just watched a youtube video about this,… Harley Davidson Glow Sign - YouTube

6

i think you may have just walked away to soon. watching other videos it seems you gotta keep on top of the bubble thing a lot longer than 15 minutes

7

John,
Thanks for sharing that video. I think that is the same problem that I had going on. Sealing with epoxy might just be the ticket.

I don’t think that I gave up on the bubbles too soon. I waited until the heat gun was having no real affect (the resin was stiffening up) before I stopped. Based on where the bubbles are I think it came out of the wood throughout the night. All the videos I saw of bartops showed sporadic random bubbles (which I had lots of and cleared with the heat gun). These seem to be focussed on the one corner and congregated to the high spots of the wood, as if they flowed right off the corners of the wood.

I’m also going to look at it again when I get home this evening. If the bubbles are on the surface, I might be able to sand the epoxy down and then cover with a 2nd coat. I’m at a point where I have some left over but not enough for a full redo so I may try that first depending on how deep the bubbles appear to be.

Thanks all for the pointers.

8

Your shellac was probably not the culprit, since shellac dries pretty quickly and as you specified dewaxed the alcohol won’t react with epoxy in any way. My guess from the location of the bubbles along raised profile edges is that you didn’t have a good enough seal and some air bubbles seeped out of the layers of ply in those spots.

Torching or heatgunning thin epoxy fills is more for breaking surface tension to let the bubbles in the epoxy or between the epoxy surface and the wood surface release and migrate thru the thickness. You need to do it carefully too…just enough you see the bubbles flow, then leave that spot. Too much and you’re actually heat-curing the epoxy quicker, which makes the longer-timeline bubbles trap under a surface skin. Air that continues to bubble out thru the workpiece because it’s face wasn’t sealed is another story…either it comes out so late it’s trapped as you found here, or if there’s enough seepage you end up with a sub-level fill.

I’d try more of a seal coat first, maybe even a thin varnish type layer (alkyd resin based not poly - I’m a big fan of Pratt and Lambert #38 clear, diluted 50/50 with naptha or mineral spirits and just wiped on in very thin coats with a rag or pad. It’s a soybased oil so won’t yellow over time. But after a few thin varnish layers you need to wait for a complete cure before attempting an epoxy…like a week. I have only ever gone the other.direction - used the 38 over epoxy-fills in wood, but if it sticks that way it’ll stick the other way too.

The one other piece of advise I’ve heard is to be doubly-sure to seal the exterior edges - even a pore filler or putty type product prior to the shellac coats - so the plywood isn’t breathing in from perimeter to interior between layers. But that would only help for the bubbles around your outline. There are also thinner epoxies from other companies designed for truly flood-fills in anything (e.g.even over paper and coins and bottlecaps like in a bar) that might be more forgiving, but if you were already at a 24 hour cure (I didn’t look up the Famowood product) you were already using one of the thinner choices.

9

@MatthewPaden

That’s a bummer. At least you didn’t carve it by hand! That’s an interesting concept about plywood being permeable. I hadn’t thought about that. Whenever I build a work bench, I always epoxy in a tape measure into the top. There are sometimes bubbles, but its a workbench, not an art piece so I didn’t think about it until now. I think sealing it with a thin layer of the same epoxy and letting that cure overnight will do the trick, then do the fill.

I’m not a huge fan of Famowood products. We sold their products at a place I used to work and their wood filler didn’t harden and ruined a piece. There are other products from companies that specialize in epoxy. I’ve got some Mirror Coat from System Three that’s waiting for a project.

Good luck and thanks for sharing the non-successes also. I think that’s almost more important than showing off a finished product.

Chris

1 Like
10

Thanks for sharing this, sometimes you learn more by seeing other people’s mistakes than from seeing their successes. Hope you get it resolved, it did look really slick after you applied the epoxy (but before the bubbles showed up) :slight_smile:

11

I have a little experience working with epoxy to seal plywood. I built this coffee table out of red oak and used plywood for the top that is covered beneath the bottle caps.

Before putting the bottle caps down, I applied a thin layer of epoxy to essentially seal the wood. I used a foam brush and put just enough to ensure it was fully coated and not much more. Even though it was a really thin layer, I still used a propane torch to ensure the bubbles came out. I spent a good 20-30 minutes working on keeping the bubbles out. After gluing down all of the bottle caps to the (now dried-maybe a day or two later) layer of epoxy, I poured epoxy over the bottle caps. With this being such a large area, I recruited some help and had two propane torches helping to get the bubbles out of the epoxy. In my case I heated it up too much as the glue began to let loose, resulting in the caps moving slightly and even more bubbles. We spent close to two hours working with it to ensure the bubbles did not show (and keeping the caps in place).
So from my experience I would say that the problem was that 15 minutes was not long enough for how deep the layer of epoxy was. If they were all gone after the 15 minutes, I would continue to check back every 10-15 to give it another go over with the heat gun. Every time I thought I was finished, more bubbles appeared.

12

I’ve never used this, but I use lots of other system 3 stuff when I’m boat building, and so you might want to consider this:

13

In spite of the subject matter… (I am a SPARTAN), this thing is pretty freaking awesome.

P.S. I hope somebody beats them before we have to.

14

BrandonHeyman- I did some small projects with epoxy but nothing as large as your pics. Very nicely done (even coming from a WI guy)! I am curious if you found a decent source for the epoxy as it seemed everywhere I looked you would think the epoxy was gold. If you have a good source and are willing to share please do. Thanks!

V/R

J.R.

15

Degassing the epoxy before pouring has helped me substantially. Slow cure epoxy, 30-40 minutes under vacuum and your need to torch out bubbles is reduced SIGNIFICANTLY. The degassing process is also interesting trying to apply the right amount of pull without overflowing the whole mess. It’s worked for me.Uploading File Sep 16, 6 52 53 PM.jpeg…

16

Thank you all for the pointers.

I tried to sand down my project tonight far enough to get the bubbles to sand off. It worked— somewhat. Most of the bubbles were near the surface and now they are gone (or at least open so a new coat would fill them). There are quite a few bubbles deeper in the pocket though and I’m afraid they are there to stay.

At this point I’m giving up on the project and re-doing it completely starting with a new carve. I’ll report back (probably take a week or so).

17

I’m curious, could you use a large drill bit (>1/4") and drill down to where the bubbles are open? The large taper might ensure you don’t have a super small hole that epoxy would flow over but not into.

18

Good thought. When I was doing my metal-filled epoxy in knots etc. in my desk project, I had some spots that the metal reacted with the amines in the epoxy (bronze turned ‘dark grey’) more than I liked…I just used an Xacto type knife to carefully carve it back out, then mixed another batch with a better metal ratio and redid the fill.

With clear it might be hard to get a clean surface with a drill bit that the new epoxy will cling to enough that the border isn’t seen, but a steady knife cut might do a bit better.

19

Since this project is a loss at this point anyway, I’m actually tempted to see if I can mill down the epoxy with x-carve deep enough to get under the bubbles. It will leave a real rough surface that I’ll have to sand up before I reapply my leftover epoxy, but it might be worth a shot.

I spent a lot of time last night with the orbital sander and quite a lot of the bubbles sanded away. It left the surface very dull but from what I understand about epoxy it should fill clear again if I apply over a sanded coat? At least that’s what YouTube would have you believe.

20

This was going to be my suggestion as well. I think this is the most effective method for removal of bubbles, especially if they are a result of air trapped in the plywood. But a degassing or vacuum chamber can be a bit pricy, as I understand it. An alternative may be a makeshift DIY vibrating table. I’ve never actually worked with any of this, just read about it, so take it for what it’s worth.