Pore filling for Tru Oil finish

Gingerninja · #1 02-04-2021, 01:58 AM

Hi
I hope everyone is safe and well. I am a new member here but have been following the forum for a while, I've been been building guitars for about 2 years now, purely as a hobby and always will be. I am coming towards the end of a European spruce/European walnut build and planning on using a Tru Oil finish for the first time. Previous builds have been French polished with pretty good results overall. I like FP but want to try something different. I have a few questions which I'd really appreciate help/answers with if possible?
1) Pore filling? Normally I use shellac and pumice but I don't think this is an option. Would it work if I sand right back and remove the shellac wash coat? If not what other pore filling options are there?
2) When to glue the bridge? Does anyone have experience of gluing the bridge pre-varnish and/or post varnish. I usually glue the bridge after FP and scrape the shellac away.
3) Any recommendations for what to finish the bridge with? Will Tru Oil be OK?

Sorry for the amount of questions, any answers would be most appreciated
Thanks
Al

steelvibe · #2 02-04-2021, 02:53 AM

Quote:

Originally Posted by Gingerninja

Hi
I hope everyone is safe and well. I am a new member here but have been following the forum for a while, I've been been building guitars for about 2 years now, purely as a hobby and always will be. I am coming towards the end of a European spruce/European walnut build and planning on using a Tru Oil finish for the first time. Previous builds have been French polished with pretty good results overall. I like FP but want to try something different. I have a few questions which I'd really appreciate help/answers with if possible?
1) Pore filling? Normally I use shellac and pumice but I don't think this is an option. Would it work if I sand right back and remove the shellac wash coat? If not what other pore filling options are there?
2) When to glue the bridge? Does anyone have experience of gluing the bridge pre-varnish and/or post varnish. I usually glue the bridge after FP and scrape the shellac away.
3) Any recommendations for what to finish the bridge with? Will Tru Oil be OK?

Sorry for the amount of questions, any answers would be most appreciated
Thanks
Al

I've used Tru-Oil with great success, and on my first try. It's very forgiving but you do need patience with it (many coats and in between dry time). This was not a build from the bench up but rather a re-finish. I used Tru Oil filler because I applied it to an all sapele guitar (very porous), and also because it was recommended by the company and is completely compatible with Tru Oil. I didn't do any sanding when applying the filler, just rubbed it in and used almost the whole bottle.

I performed the application on a satin finish guitar and so I took steel wool to the surface before proceeding. I removed the pick guard but left the bridge and just closely masked with painters tape all the way around it and around the neck join. I applied at least 12 coats of Tru Oil with at least 1.5 hours drying time between coats. It took me over a week to get the result I wanted. On the last 2 coats I thinned down the Tru Oil with a bit of mineral spirits. This gave a near poly gloss shine. I didn't put any Tru Oil on the bridge (which was Richlite on that guitar). Any overwork I was able to gently just scrape away from the Richlite. I know Richlite is controversial but I personally love it and would buy a guitar with it again in a heartbeat. Very hard, feels like ebony, looks like ebony, stable and strong- what not to like?

You might want to do some internet sleuthing about using Tru Oil on the bridge and based on what it is made of. There are also videos out there with regards to use with spruce tops. I think it is a little trickier to use on spruce but there are gorgeous guitars made with it so it can be done. YouTube has a lot of great videos with using Tru Oil on basses, electric and acoustic guitars.

Good luck!

nikpearson · #3 02-04-2021, 03:10 AM

Have only finished one guitar with Tru-Oil, but also refinished it at a later date as I wasn’t happy with the result.

1) Pore filling: I’d be concerned over how well the Tru-Oil would adhere to shellac. You could apply the oil then knock it back (several times may be needed) to fill the small pores in the walnut. I quite like look of leaving the pores.

2) When to glue the bridge? I glued before finishing and it was challenging to get a really clean finish around the edges of the bridge and fingerboard. When French polishing a I’ve masked of the exact area of the bridge with Scotch tape to leave a clean surface for gluing. This approach should work with Tru-Oil but as it builds more quickly than shellac you’d need to be very precise with the masking.

3) Bridge finishing: you can certainly finish the bridge with Tru-Oil but I don’t see the need. I have a friend who achieves a high gloss shine on the bridge using Tru-Oil, but I don’t like this look and it will probably mark up quite quickly. My preference is to polish the bridge paternal with. MicroMesh and then possibly use a light coat of fingerboard oil.

Another issue I’ve had was using Tru-Oil on a Spanish cedar neck. After a few weeks what started out as a lovely smooth neck became slightly rough to the touch. I can knock this back with very fine wire wool, but it will return a few weeks later. This is down to skin chemistry as the back of the headstock exhibits the same issue. It almost feels as if resin is precipitating out of the wood and crystallising on the surface.

Having used both oil and shellac finishes I have to say I prefer the latter. Getting a good oil finish is just as hard as French polishing and not that much less time-consuming. You also have the option of everything from a high gloss to matt finish with shellac. Whilst you can get a reasonable shine with Tru-Oil it’s never very glossy.

I suspect that with practice I could achieve a much better oil finish. The same friend uses Tru-Oil for all his instruments and the recent ones look very nice. Incidentally he never pore fills.

Always worth experimenting.

BradHall · #4 02-04-2021, 10:25 AM

I’ve used Tru-Oil on numerous builds. I have pore filled with egg whites, shellac, and water based fillers on different builds and have had zero adhesion problems with it. As was mentioned, many light coats are preferable. I had the same issue on my first attempt trying to add “just a little more” after the bridge was glued down. Big mistake that was never quite right.

Gingerninja · #5 02-05-2021, 01:49 AM

Brilliant, thank you everyone for the words of advice, it's great to hear differing thoughts.
I think the walnut B and S would look best with an Tru Oil finish rather than my usual high gloss FP and as I said I fancy something different which is exciting in itself. I've just ordered some BC filler/sealer so I will try that, the pores aren't large and it seems easy to use. I presume I should just to use the filler/sealer on the back, sides and headplate (ebony)? The neck is maple and doesn't need pore filling.

nikpearson · #6 02-05-2021, 07:27 AM

I’m also thinking you could use the same approach to filling as you do with French polishing: that is make a slurry of of wood dust, Tru-Oil and pumice powder. Worth trying on a scrap of walnut. Perhaps you could even just sand the wood with Tru-Oil and abrasive paper.

Think I might try some of these suggestions on a future build.

Let us know how things go...

Gingerninja · #7 02-06-2021, 02:06 AM

Thanks again for the advice, I did wonder about pumice and tru oil but wasn't sure if it would dissolve in the same way as with alcohol. There's obviously an easy way to find out!
Here's a picture of the back after a quick wipe with white spirit, this is more like the type of finish I want, not high gloss but more satin. I'll update on how it goes, need to finish sanding and sorting any blemishes for now though.

https://www.flickr.com/photos/192044...shares-419317/

nikpearson · #8 02-06-2021, 07:08 AM

The back and sides are looking very nice. Lovely figure on the back. Figured walnuts are some of my favourite woods.

I may have misunderstood what you meant, but the pumice powder isn’t dissolved by the alcohol. It’s finely ground volcanic rock which can be used to abrade the wood. When coupled with alcohol the wash coats of shellac are dissolved and the resulting slurry of pumice, liquid shellac and wood dust fills the pores. The pumice grit is very fine so either the white colour gets hidden within the slurry or perhaps it absorbs colour from the wood slurry, I’m not quite sure. Occasionally you can see specks of white pumice in finished instruments.

This post is going to get me experimenting with pumice & Tru-Oil.

As an interesting aside I’ve also used Liberon Danish Oil containing a UV protector as an undercoat for Tru-Oil in hope that it would prevent purpleheart binding and purflings from losing their vibrant colour. Four years and counting and the colour is still very much there. Another 5 years or more before I’ll be confident it has worked.

The Watchman · #9 02-06-2021, 09:45 AM

like danish oil, Tru Oil is a mix of oil and urethane (a varnish) which gives it the glossiness. Not solely an oil, so it has properties of both. Something to consider if you're concerned about compatibility.

Gingerninja · #10 02-06-2021, 11:01 AM

Quote:

Originally Posted by nikpearson

The back and sides are looking very nice. Lovely figure on the back. Figured walnuts are some of my favourite woods.

I may have misunderstood what you meant, but the pumice powder isn’t dissolved by the alcohol. It’s finely ground volcanic rock which can be used to abrade the wood. When coupled with alcohol the wash coats of shellac are dissolved and the resulting slurry of pumice, liquid shellac and wood dust fills the pores. The pumice grit is very fine so either the white colour gets hidden within the slurry or perhaps it absorbs colour from the wood slurry, I’m not quite sure. Occasionally you can see specks of white pumice in finished instruments.

This post is going to get me experimenting with pumice & Tru-Oil.

As an interesting aside I’ve also used Liberon Danish Oil containing a UV protector as an undercoat for Tru-Oil in hope that it would prevent purpleheart binding and purflings from losing their vibrant colour. Four years and counting and the colour is still very much there. Another 5 years or more before I’ll be confident it has worked.

Yes I'm pleased with the walnut, cheap too, just got lucky with the piece the pickers selected at Madinter. It was really easy to work with too, no tear out and bent each sides in about 20-25 mins, which is a record for me!

The misunderstanding is mine, I thought the pumice dissolved/cleared with the alcohol. My hope was that I could learn a lot from this forum, so thank you, much appreciated. I'd be interested to know how you get on with TO/pumice when you get chance.

I believe a few people have used Danish Oil for their finish, a part time luthier in the UK recommended it but I've not been able to find anyone who uses it as a finish for acoustics.

Gingerninja · #11 02-13-2021, 05:29 AM

I've now started on my first Tru Oil finish. All good so far but taking it easy and trying to be very careful as I learn the process
The Tru Oil sealer and filler worked well, easy to apply. I followed the instructions, perhaps not applying as liberally as it suggests, sanding lightly between the two coats with 400 grit. One thing here, although it seemed fully dry, when I started to apply the second coat I then realised it wasn't as it was just a touch 'sticky' when applying.
I've now applied one coat of the Tru oil which I'm applying with a lint free cloth wrapped in another cloth, essentially a FP rubber. I'm trying to keep the coat as thin as possible. Pictures in the link below, any tips most welcome. I also decided to follow the same process for the ebony bridge.

As to the Tru Oil coats being fully dry, any advice on how to tell. Also it's really cold in the UK at the moment, I presume that will slow the drying time?

https://www.flickr.com/photos/192044.../shares/50x7KK

https://www.flickr.com/photos/192044.../shares/5Lji5d

BradHall · #12 02-13-2021, 10:25 AM

Looking real nice. Yes, cold conditions will retard drying times. On a warm day I usually do 2 to 3 coats.

Gingerninja · #13 02-13-2021, 10:48 AM

Managed to get two coats in today which is great. I'm keen to reduce the 2 - 3 weeks when French Polishing. I think I am starting to get a working method now. Like everything, it's only when apply a technique that you start to understand it.

Gingerninja · #14 02-16-2021, 12:18 PM

Progressing nicely now, 8 coats on now and really beginning to develop the technique of thin coats and then wiping off. Starting to get a decent build of finish now, it's not perfect but looks pretty good. A few questions if anyone can help?

1) Final sanding. I was thinking of sanding with 600 or 800 girt before the last 2 or 3 coats, any advice? I do have some fine marks on the surface in a few places, I think this may have been due to the first couple of coats being a bit thick but not sure.
2) Does anyone have any experience of finishing the last few coats with a thinned mix of tru oil and mineral/white spirit? If so, any tips? I believe this gives a glossier finish
3) Finally, when I FP I usually to finish with Novus 2 and carnauba wax, is it worth it?
Thanks in advance for any help
Al

Monts · #15 02-18-2021, 10:26 AM

Quote:

Originally Posted by Gingerninja

Progressing nicely now, 8 coats on now and really beginning to develop the technique of thin coats and then wiping off. Starting to get a decent build of finish now, it's not perfect but looks pretty good. A few questions if anyone can help?

1) Final sanding. I was thinking of sanding with 600 or 800 girt before the last 2 or 3 coats, any advice? I do have some fine marks on the surface in a few places, I think this may have been due to the first couple of coats being a bit thick but not sure.
2) Does anyone have any experience of finishing the last few coats with a thinned mix of tru oil and mineral/white spirit? If so, any tips? I believe this gives a glossier finish
3) Finally, when I FP I usually to finish with Novus 2 and carnauba wax, is it worth it?
Thanks in advance for any help
Al

I run steel wool instead of sandpaper on it before the final coats.

I use the thin mix most of the time on all coats, I don't really measure but because I've done it a few times I can usually tell how much of each to mix in visually, maybe a 3:1 ratio?

I never used Carnauba wax in the end but some do.