2nd attempt at resin filled coasters - advice needed

Things You've Made
#1

Here are some simple 100mm coasters, made from off-cuts of oak floor boards.

For the first ones I used a black acrylic paint pen to highlight the letters, sanded off the excess then oiled the whole thing. Unfortunately, despite a coat of varnish before the paint, and leaving it the black paint a couple of days to cure, the oil softened the paint and it bled :frowning:

For the second attempt I used some Decorum epoxy resin pigments that my wife had given me for Christmas instead of paint. Learning from my first attempt, I brought the epoxy into the house to warm up, which made it more runny and allowed the bubbles to settle out. There are still a few little bubbles - is there any way (short of a vacuum chamber) to prevent them?

I also under-filled the larger letters slightly, so they didnā€™t get scratched when I sanded off the excess, but this didnā€™t work for the small letters (the grooves are only about 2mm across). Is there any way to keep the nice glossy, translucent finish? Or a way to get the epoxy in there that doesnā€™t require sanding afterwards?

Another thing I learned from last time was to engrave a circle around the outside of the coaster with the V-bit. I can then use this to as a guide to cut it out with a band saw, rather than risk a tool change.

Coasters
Coasters4608Ɨ3456 2.47 MB

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#2

Higher grit sandpapers will remove the haze from the top of the epoxy when sanding. You can also buff and polish it.

I used a torch to remove bubbles from the epoxy. The heat seems to help pull them to the top so they pop.

#3

You could also try a heat gun.

#4

Thanks guys - how careful do you have to be when heating epoxy with a heat gun? Is it easy to over-do it?

Iā€™ll have a go with little buffing wheel on a Dremel - do I need to worry about marking the wood?

#5

Havenā€™t done the torch thing myself but seen several videos online. I think youā€™d get the technique down pretty quickly after scorching a practice piece or two. You might even be able to accomplish it with a hair dryer. The warmth both expands the air trapped in the bubble and lowers the viscosity of the ā€œshellā€ of the bubble, so they seem to pop pretty quick and easy.

#6

This site actually says that a torch is better (like @niget2002 & @ttraband suggest) since it gets hotter and is less likely to blow dust onto your workpiece.

It also compares other methods and gives some instructions on how to do it. Hopefully this gives you better results. Best of luck!

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#7

Iā€™ve used a heat gun on all my epoxy pours, takes the bubbles out real nice. Iā€™m sure a torch would work just as a good, but my dumb butt would scorch the wood ( Iā€™m not very talented, hence the cnc lol)

As for the finish , u have two options. Donā€™t fill it all the way and have that cupped look, or fill and sand ( sanding u just need to go tinhiger grits and it will polish right up)

#8

Just a suggestion, but I used a forsner bit to put 1/2" recesses in a scrap piece of wood. This allowed me to test a few mothods and colors before attempting my final piece.

I also learned to use thin ca or a very thin coat of epoxy to seal the wood before doing the final build. Otherwise it tend to get bubbles from air trapped in the grain of the wood.

Iā€™ve honestly only done a few projects with resin,but I learned a lot in testing.

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#9

Thanks everyone, Iā€™ll have to give the torch a go.

How high do I need to go with the sand paper grit to polish the surface?

#10

I use to use the headlight restoration kits from harbor freight to polish up the surface, but that was probably over kill. Next time Iā€™m there (basically daily) Iā€™ll grab a kit and see what results I can get using the least amount for ya.

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