Filling tiny holes in benchtop

Hey All,
I've had some raw kitchen benchtops made from recycled messmate which I now need to fit, do cutouts, oil and join. I'm a total newby so figuring things out as I go. Probably bit off more than I can chew but hopefully the end result won't be too bad and I get to learn a lot along the way! The benchtops are beautiful and already drum sanded with large holes filled, however there are some tiny holes that have not been filled. The company I bought from recommend a polyurethane finish which I assume would just fill these up, however I am planning to use Polyx Top Oil. So couple of questions:

• for a kitchen benchtop should all tiny holes be filled so you have a totally flat surface? I figure they'll fill up with grime anyway if I don't!? Or would the wax in the Top Oil fill these?
• what is the best product to fill these (1-2mm) holes? Ideally in black to highlight the imperfections rather than trying to hide them. Are there any special tricks to filling such tiny holes?

No doubt I'll have more questions as I go so thanks in advance for you patience!
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Welcome to the forums.

Those look like the holes made by pinhole borers with some later staining from fungal infection. If there's no sawdust coming out then the borers have most likely departed. If it was me I'd pour some denatured alcohol ("Metho") on the surface to make sure both borers and fungi are dead. That evaporates quickly. It may raise the grain and require a quick hand sand afterwards.

For good hygiene a kitchen bench should be smooth and impervious so I suggest that you fill the holes completely. I would use an epoxy with some black or other desired colour in it. I have used Boatcraft Pacific's Epox-E-Glue for such purposes. It will mix with either a colouring powder (as used with cement if finely ground) or, more easily with a spirit stain like Wattyl craftsman spirit stain (available in colours as well as straight black). The spirit stain thins the paste-like epoxy and makes it easier to get into the holes. Press it in with a palette knife or similar. Wait 24 hours then sand smooth. if you use blue painters' tape to surround the holes it is more work up-front but will ensure less cleanup and sanding afterwards.

You could also ask the makers Boatcraft Pacific directly whether they have a better suggestion. I think that they are sponsors/advertisers on these forums or a quick internet search will find them.

The traditional filler is an adhesive mixed with some sawdust but I suggest that would be too coarse for your needs here.

Good luck,

David

If it were me, I'd probably fill those pin-holes with Epoxy.
I use Bote Cote, but there are lots of 2 part systems to choose from (West System, Total Boat, etc.).

Epoxy sets clear, and usually has a light amber colour to it. Sometimes you can barely see it. Or, you can add a pigment and make it whatever colour you like. I've used the Luci Clear Black with Bote Cote, and it works great.

Matt Cremona did a pretty good video on this kind of epoxy repair work. I found it helpful.
Filling Voids, Cracks, and Defects in Wood with Epoxy - Ask Matt #19 - YouTube

I use a plastic cup to mix, weighing the resin and hardener with my coffee grinder scales (accurate to .10g). Then I use a disposable syringe (no needle) to get it where I want it.

Once it sets up, I use a hand/block plane, card scraper or chisel to get it basically flat. Then some sanding to take care of any 'staining' where the epoxy has permeated into the open grain.

Have a think about how you want to prep the top for finish. it's probably been drum sanded to 100 grit or so. For Osmo, I usually stop at 240. Bit of a task on a counter that big.

You can use polyurethane on the pinholes but it would be best to inject into each hole. If you try to drip feed into each hole it will be very time consuming and frustrating.
My experience in using masking tape on the underside has been a big failure and you only find out when you see the wet patch on the floor.
Before you fill (or try and fill) the pinholes with resin give them a bit of a reefout/enlarge the hole slightly with a 6mm drill bit or a countersink bit as it will be easier to fill then trying to do a tiny pinholes.

So long as all the holes are about the same small size (1-1.5mm) another option is to wet sand the first coat(s) of oil.

This is a messy job and will only fill the top few mm of the bores at best, but it's how many, many bench surfaces have been finished given the same situation.

I recommend only sanding a small area at a time, using the same grit of paper as you'd ended with when sanding the tops.

Work the slurry into the holes while you're sanding, but work quickly. The oil will quickly go tacky and start 'balling up.' Stop sanding then, there's no gain in sanding further - actually, it can be detrimental - although if you're quick enough you can coax some of these 'balls' into other holes with a paint scraper/putty knife/whatever to help fill them, too.

When finished, the surface will probably look a mess, but another dry sand should bring it back to smooth. Keep an eye out for any dimples that aren't fully filled; it may take a couple of extra wet sands to do a proper job. Wait a few days between each sanding, as you want the oil to set up properly for full adhesion. (It sucks when you're too quick and the sanding process removes the effort of your prior work. DAMHIKT. :- )

Minor dimples will generally fill when you apply the finish coats, but 'tis best to try and get the holes filled as flush as possible.

Thanks for suggestions and the link!

Yes good point on the sanding taking a while. I was thinking do 180 with the orbital and see how it is, then 240 if needed. I haven't used Osmo before though!

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Originally Posted by rod1949

You can use polyurethane on the pinholes but it would be best to inject into each hole. If you try to drip feed into each hole it will be very time consuming and frustrating.
My experience in using masking tape on the underside has been a big failure and you only find out when you see the wet patch on the floor.
Before you fill (or try and fill) the pinholes with resin give them a bit of a reefout/enlarge the hole slightly with a 6mm drill bit or a countersink bit as it will be easier to fill then trying to do a tiny pinholes.

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Good to know about the tape! I'll experiment with drilling some test holes out bigger and give that a shot too

Thanks everyone, lots of suggestions! I've ended up picking up some West System epoxy and black pigment (combo of your suggestions and what was available at local wood shop) and will give it a crack over the weekend on a test piece
:fingerscrossed: