Wood Coasters from Tree Branch finish

Question

My family just chopped down an old silver maple tree in their backyard. It has some great branches that are about 2-3 inches. We thought that slicing them and cutting them up into thinner pieces to make a some nice drink coasters.

The plan is to have a nice bare tree look with them. The bark is thin on these in this area. We want it to have a nice natural look, and possibly something to show off the rings of the tree. Nothing dark, nothing that will change the color/hue too much.
There won't be a need to make it food safe, as its just for cups and glasses. They will potentially be used outdoors on the patio. I would like them sealed so they will retain their look for a long time. However, I also don't want anything that will smell (in case they are used in the house or in the enclosed patio room). Something that would also stand up to the elements (to some extent) if they are left out.

My question is do you think that they need any type of finish on them?
And if so, what kind what do you suggest?
Should these also be dried out, and if so for how long before a finish?

I know some of this might be opinion based, and I appreciate everyone's opinion and thoughts on that. Overall, looking for a what works best, and what is a good thought on sealing a wooden coaster that is sliced from a tree branch.

Answer 1

My question is do you think that they need any type of finish on them?

I think it's vital, yes. The top and bottom surfaces of slices like this are all end grain, and unsealed end grain is absorbent like a sponge. Even the slices that dried without cracking to begin with have the potential to crack and/or warp again each time they get damp or wet.

And if so, what kind what do you suggest?

Personally I think wax is the way to go here. I normally prefer finishes like varnish that dry hard, but for this the wax can be soaked into the wood in a very simple way that doesn't require any complicated or expensive setup.

• Buy an inexpensive wax such as canning wax, or any other pure paraffin wax. You could use beeswax but it generally costs a lot more and there's no benefit here AFAIC, and it's usually yellowish to orange in colour while paraffin wax is white.
• Melt the wax carefully over a low heat or in a double boiler/bain marie.
• Once the wax is fully melted submerge the slices one at a time until they stop bubbling. They'll want to float, so you'll either need to hold them under with tongs or something or place something small and heavy on top to keep them submerged.
• Once bubbles have ceased to be released from the wood this should indicate that it's absorbed as much wax as it can take so remove them, wipe/scrape as much excess wax from the surface as you can and put aside to cool.

Once they're at room temp you can scrape any remaining wax from the surface, buff them with a cloth and they're ready to use.

Should these also be dried out, and if so for how long before a finish?

As with all wood drying, you do it as long as is necessary to get the wood down to a suitable moisture level. Without a moisture meter I think the only way to check this is to weigh them until they stop losing mass.

The other option would have been to stabilise the wood in PEG or Pentacryl but I believe this needs to be done immediately after cutting to be effective.

Answer 2

The biggest problem I see with your plan is that discs cut from a branch as mentioned are going to be chronically bending and warping even after they are properly dried out.

One option you could consider is casting them in clear (or colored for that matter) resin.

This would be a pretty simple process for what you are planning you simply need a dish slightly deeper and wider than the disc. Once coated in resin you can trim the edges and sand/buff it smooth and shiny. Realistically they should pretty much last forever...