Nail-holes filler for merbau decking

Good day,

I'm refreshing my merbau deck - stripping all the boards, planing, sanding, cutting away cracked/rotten end and then re-arranging with what's left.
The issue that I'll be left with lots of old nail holes mid-board. While I don't expect it to have a significant impact on boards' life span, it's visually unpleasing so I think to fill them with a putty.

I'm finishing it with Cutek CD50 + colourtone which get sucked into wood and doesn't create any film. Hence the putty needs to have colour close to merbau or accept stain very well. And of course it needs to be fit for outdoor decking purposes with regards to sun and rain.

I also want to cover screw heads with the same putty - CD50 doesn't, again, create film so the stainless still heads will be catching on the eye which I'd rather avoid.

I did a quick research and there is seemingly little info on the subject. One thing I found is Earl's MulTfill which says its for exterior use and even come in merbau color (i'm not fussy colourmatch too much - it will never be perfect).

Any other recommendations?

Thank you in advance.

Rather than using wood filler how about wooden plugs?

Old fashioned recipe "Painters Putty" or "Glaziers Putty" will last probably longer than the modern "fillers." It wont look as good as the tinted "fillers" but has stood the test of time in many old homes.

Save your saw dust in a jar and mix it with an exterior grade glue (like pva) or even mix it with your finish if you are using one that will dry, I have found Cutek to be a very good finish but will not be able to mix dust with that finish you would have to use glue.

As someone with a LOT of merbau decking, I don't reckon anything will hold. Decking cops an absolute flogging from the elements- both thermal and moisture expansion/contraction. If you must go down this path, use something flexible that doesn't set hard. Maybe black Sikaflex Pro?

Dunlop 310ml Coloured Silicone - Travertine - Bunnings Australia

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Originally Posted by Mobyturns

Old fashioned recipe "Painters Putty" or "Glaziers Putty" will last probably longer than the modern "fillers." It wont look as good as the tinted "fillers" but has stood the test of time in many old homes.

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Can you share the recipe please?

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Originally Posted by Camelot

Save your saw dust in a jar and mix it with an exterior grade glue (like pva) or even mix it with your finish if you are using one that will dry, I have found Cutek to be a very good finish but will not be able to mix dust with that finish you would have to use glue.

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That's an idea! My deck is covered and with side walls (like a balcony) so doesn't get that much rain. Wouldn't cover screw heads with it (or I'll curse a lot if I ever need to clean the head to take the screw out) but fixed with my favorite Weldbond glue it should work.

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Originally Posted by Chief Tiff

Rather than using wood filler how about wooden plugs?

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I'll have to work out how to make about 1000 plugs first. I love my deck but that's too much :)

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Originally Posted by aeroden

Can you share the recipe please?

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I haven't made any in a long time now. Traditional glaziers / painters putty was made from raw Linseed Oil (though boiled can be used), whiting (calcium carbonate / calcite / limestone powder) and in some cases Zinc Oxide was also added. You basically add the Linseed Oil a bit at a time to a quantity of whiting and knead until you make the putty the consistency of "bread dough." It will keep in a sealed jar for months but won't keep as long as commercial "putties." You will find that making the putty a bit on the wet side will make it easier for hole filling, and dry firm mix for glazing.

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Originally Posted by aeroden

I'll have to work out how to make about 1000 plugs first. I love my deck but that's too much :)

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The plugs don't have to be fancy. We used to rip slivers of matching wood then simply drive them into the hole with a flooring hammer, like driving a wood nail. Use a framing chisel inverted (bevel down) to trim off excess.

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Originally Posted by Mobyturns

The plugs don't have to be fancy. We used to rip slivers of matching wood then simply drive them into the hole with a flooring hammer, like driving a wood nail. Use a framing chisel inverted (bevel down) to trim off excess.

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Wouldn't plugs absorb moisture through the end grain over time and start to stick out from the board?

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Originally Posted by aeroden

Wouldn't plugs absorb moisture through the end grain over time and start to stick out from the board?

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Nah; wood doesn’t expand along the grain very much at all. Across the grain is a different story… Any subsequent sticking out will be caused by the decking board shrinking as it gives up moisture but this will be measured in fractions of a millimetre.

How about traditional wooden plugs to cover the screws; and tapered plugs hammered into the nail holes? One company used to make a pointy tapered drill bit that you drilled into a blemish, then took a dowel of your plugging timber and put it into a pencil sharpener to get the matching taper. Bit of glue, wack it in and trim flush.

I don't know what the real answer is, but I'd suspect glued pegs is it.

If you were to make plugs, which strikes me as the best idea so far: DFM A2 Steel Dowel Plate 17 Holes MADE IN USA (Metric 17 Holes) : Amazon.com.au: Home Improvement

Drill the hole to something consistent, such as 5mm, cut strips of an existing board, bang them through this plate and glue the resulting dowels in with something like Titebond 3?

As for poking up with shrink/swell over the years, when one oils the deck the end grain will suck that juice in real fast. Regular maintenance might help?


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Originally Posted by Chief Tiff

Rather than using wood filler how about wooden plugs?

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I’m just in the finishing stages of a Deck for a client, would you like to quote for 700 ish screw holes too be timber plugged [emoji6][emoji6].

An it’s a small deck !!.

Cheers Matt.