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Filler for Oak

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Dr Al

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I've been experimenting a bit with the colour that can be achieved with different wood fillers. I think I might have done something wrong as I didn't get the results I expected.

I started with a bit of oak, nailed to a scrap of pine in 12 places.

Four of the holes (over the nail heads) were covered with Osmo White Oak Filler

Four were covered with Osmo Mid Oak Filler

Four were covered with a mixture of Titebond Original glue and oak sanding dust (take from the bag of my random orbital sander after thoroughly cleaning it out and then doing lot of sanding of oak). I was expecting a better colour match from the oak fillers (perhaps I need a darker one); I definitely wasn't expecting the oak dust and glue mix to go black!

This photo was taken after sanding the test piece down a little (although it looked fairly similar before sanding).

1598195026880.png


Am I doing something wrong? Is Titebond Original a bad choice for this for some reason?
 

Sgian Dubh

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Did you mix it with a metal implement?
Specifically, I think Mignal is asking if you used something that has a significant ferrous content, e.g., steel instruments, tools or containers, or even if the water has iron in it? Slainte.
 

Dr Al

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Did you mix it with a metal implement?
Specifically, I think Mignal is asking if you used something that has a significant ferrous content, e.g., steel instruments, tools or containers, or even if the water has iron in it? Slainte.
I don't **think** I did (I'm pretty sure I used a plastic thing that came with some epoxy). The oak dust was stored in an Altoids mint tin prior to use though (it was removed from there and mixed with the glue in a silicone glue tray thing). Do you think that could have caused the issue?

I'll have another go when I've done some more sanding and make sure that the dust doesn't go near anything ferrous.
 

MIGNAL

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Yes, iron + tannin content of oak equals black stain. Try again with new oak dust and plastic mixer. Don't really understand why the Titebond should trigger the reaction unless it has a high iron content.
 

RogerS

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Be prepared for the oak dust to look a different colour (after you've cured your 'black'!). This is because there is a high probability that it's not pure oak dust but mixed in with dust from the sanding pad.
 

MikeG.

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The dust and glue thing can give an approximate colour match.....approximate only, but because the texture is all wrong it really doesn't blend in to the wood very well. It's actually more like end grain than long grain, and if you were to stick an end-grain plug (ie a cut-off peg/ dowel) into the long grain of oak you know how much that stands out. I'm afraid that a filler which disappears into the background is as rare as rocking horse droppings. The only thing that comes close in my experience is a completely clear epoxy, which allows the colour of the surrounding wood to show through.

The other issue I've found is that fillers lighten over time, and most woods darken. So even if you get a good colour match now, it won't be so special in 5 years time, let alone 20. The only solution, unfortunately, is to design out the need for filler, and then take extra special care throughout the construction such that you don't have an accident which needs repairing.
 

Daniel2

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I've always found fillers to be awfully disappointing.
As Mike says above, try and design out the need.
These days I avoid them like the plague pandemic :)

ATB,
Daniel
 

AJB Temple

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Mike is dead on. I prefer to patch - with correct grain direction - rather than fill wherever possible.

What does work to a degree - but is expensive and a faff - is to use a two part filler, and use an instrument maker's stain to colour the bulk part before mixing in the hardener. However: it is very tricky. You have to work in very small quantities because it goes off in maybe two or three minutes. It then sets rick hard (like epoxy). I have done this hundreds of times for small repairs on instruments (guitars mainly) in my past.

Antique furniture restorers have other techniques. They will apply a near match filler, let it go off and sand, then tint in. Takes skill and practice.

There are other, reversible, methods for antiques as well (hard setting wax mainly I think) but I have little experience of that. I keep bees, so have a ready supply of wax and have experimented a bit. So far I have not found a reliable colourant, though I have tried food dies in melted wax. It always sinks when it sets, so you have to do it a few times.

I think wood dust mixed with glue is basically an old wives tale. It never looks good and generally is a worse job than commercial fillers.
 

Astrobits

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I have tried to use sawdust/glue for filling but it always comes out very dark. The attaches photo shows a scrap piece of Sapele with a screw hole filled with sapele dust and Evo-stick wood adhesive. I have also given it 1 coat of oil to see if the wood would darken sufficiently. Just as bad as the oak in Dr Al's post.
Sapele filler.jpg

Nigel
 

Droogs

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Always best to make a long grain plug if using screws in the same wood if trying to hide it or something to contrast if not
 

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