I have doing several plaques recently using epoxy but I have started having a problem. After routing out the plaque, I have sprayed the immediate area with lacquer to help seal the wood around the routed area. I have also used wax around the area and both techniques have worked alright without any bleeding into the grain around the inlay.
The last two plaques I did out of maple where terrible. Lots of bleeding around the inlayed area. Theres so much bleeding in the out lying area, it cannot be sanded out, because the bleeding has gone so deep.
I did some testing on a scrap piece of maple and did the sealing a little differently. At the time I sprayed the area around the pocket, I also sprayed down into the pocket thinking the epoxy was wicking through the sides. I then waxed around the immediate area and put the epoxy in.
1. Is the wicking just along the grain or is it wicking across the grain also? How thin is the epoxy you are using?
When I look at it, I can see it down in the grain running with the grain. I've seen it in some places and wonder how it got there. There was nothing around the area for it to even be there. The epoxy is about like syrup. Not runny at all. I'm using System 3 and use a scale to measure out the resin and hardener. No problem with the setting up.
2. What was the wood that didn't have the problem? Have you tried dewaxed shellac or zinsser sealcoat instead of lacquer?
So far it is only with maple. No issue right now with mahogany. These are the only two woods I've been using. I haven't tried the shellac or zinsser. I think I'll do a test piece and see what happens.
3. Do you have any pictures showing what's happening?
This photo shows whats happening. There was a pretty good coating over everything. The light color on the black epoxy is just dust from the trash can.
So what I think I am seeing is seeping along the grain and not across. This suggests to me that it is capillary action along the fibers that is pulling the epoxy up. Are you thickening the epoxy? Mind you even if you were the epoxy may preferentially be drawn up the fibers instead of adhering to the thickeners…. Since it seems the epoxy is too thick to absorb across fibers that a barrier is needed to fill or block the paths being taken by the epoxy. Could you precoat the grooves with clear epoxy to allow the capillary action to draw up uncoloured epoxy which, after hardening, would prevent the next coat of coloured epoxy from being drawn up?
I spray about three or four light coats of dewaxed shellac over everything including inside the routing. After that, I'll prep inside the grooves with clear epoxy until it looks like it's not soaking in. The excess epoxy gets toweled out then I start with the colored stuff.
I also use a toothpick or dental pick to put epoxy inside the grooves to avoid getting too much on the surface of the wood.
Scrape the excess epoxy off. If you sand it, you'll just embed colored dust into the wood. After everything is scraped level, you can do light sanding but the dust has to be wiped off frequently.
1. Are you thickening the epoxy?
No thickening agent being used.
2. Could you precoat the grooves with clear epoxy to allow the capillary action to draw up uncoloured epoxy which, after hardening, would prevent the next coat of coloured epoxy from being drawn up?
I'll prep inside the grooves with clear epoxy until it looks like it's not soaking in.
I haven't used epoxy yet in the grooves. If I pre coat the grooves with clear epoxy, should I then come back with the color before it dries?
You can apply the colored epoxy before the clear dries. All you're doing is making sure that any wood that's not sealed off by the finish is saturated with clear before the color goes in.
Just be sure to use slow set epoxy and wait 15 minutes after applying the clear to make sure it's done soaking in. If you see dry spots you'll need to apply more clear then wait another 15 minutes. Once the finish stops soaking in just wipe out the excess before it gets too tacky.
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