Brushed nitro finish - PICS!

[honza992]

I'm not sure whether anyone is interested, but I've just finished a guitar with a brushed nitrocellulose lacquer finish.  I always swore that I'd never use nitro - too poisenous both for me and the planet.  However, a friend asked me to make them a Tele using a beautiful piece of flamed spalted maple, and nitro was the only finish that worked.  Polyurethane, oil and CA glue turned the test pieces into a dull splodgy brown mess, not exactly the look I was going for.  Nitro though brought out all the beautiful colours and let the flame really sing.  

Here's the piece of wood before I started....

Although I do spray waterbased polyurethane, there's no way I can spray nitro so I thought I'd try brushing it on.  The internet though had almost no information about whether it was possible to brush it on, how to do it, or what the results would look like.  So, hopefully this thread will help you decide if you want to do it.  It is definitely not an easy option, but.....let me get up some finished pics, and you could decide whether it was worth it. 

This is what I used:

This is Rothko & Frost's standard gloss nitro that they sell neat, ie not in aerosol.  This was a 250ml bottle and I used the whole thing plus a bit more on the body.  I brushed it on with an artist's brush, a trick I stole from @Andyjr1515. You need to make sure that it's a brush for oil paints, with natural bristles, otherwise the solvents can melt them.  I used a Daler Rowney Bristlewhite hog hair fan brush, size  4 (though a size 6 might have made life a bit easier).  They are comically long so I cut mine to a more manageable length. 

Schedule was something like this:

1. Sand to 220

2.  Grain fill with Aqua Coat 

3.  Ignore the fact that the grain fill was pretty poor and crack on with finishing (john, john, john, will you never learn?🙄)

4.  Brush on R&K Nitro, thinned with 30% R&K cellulose thinners, probaly about 10 coats.

5.  Curse myself repeatedly for failing to grain fill properly.  I've made enough guitars to know that preparation is everything, and if you want a smooth finish grain fill is critical.  Impatience though sometimes clouds my already pretty poor judgement

5.  Wet sand with Wet/Dry paper (water with a drop of Murphy's oil soap) with 600 grit. 

6.  Another unknown number of coats. It felt like hundreds, but was probably another 5 or so. 

7.  Wet sand 1000 grit

8.  'wet' sand with Gerlitz Carnauba wax on a piece of Mirka Abralon 1000 grit.  This left exactly the satin sheen I was after. 

I found the key was to brush the nitro on in one stroke, never go back over somewhere you've just painted.  Because the nitro dissolves the layer before, I found the brush would start 'sticking' as it got caught in the previous layer.  My approach was to do lots and lots of layers, knowing that I would have to go back and wet sand quite a lot of it off to get it completely flat. In reality, because my grain fill was....well, shite.....I had to do many many more layers than I otherwise would have had to have done.  If I ever do this again, I'm hoping that 10 layers in total would be enough, assuming a flat surface to begin with.  I lay the guitar flat on a 'lazy susan' turntable, did the top and the sides at the start of the day then turned it over and did the back and sides.  

Would I do it again?  Ummm....yes, and no.  Yes, if the wood was crying out for nitro, as this piece was.  I'd be a bit reluctant to do it again on an entire guitar body though.  Even though it was brushed rather than sprayed, the fumes were still pretty bad, and I wore a proper mask with organic filters at all times.  On a guitar with a binding like this one, next time I'd probably brush the top with nitro, as above, but do the rest of the body with something else, tru oil probably.  The binding would provide a natural break between the two finishes, so the two finishes wouldn't ever touch.  And on a flat surface like a guitar top (rather than the fiddly curved inner horns) you could whizz through the process in no time. 

It's worth mentioning that the Rothko & Frost nitro specifically says it is not suitable for brushing, though I'm not quite sure why, as far as I could tell it went on perfectly nicely.  The process also used much less nitro than you would get through if spraying (I think).  With a proper grain fill I'm pretty sure I could do a whole body with one 250ml bottle.  An aerosol contains about 150ml of nitro, so I used probably the equivalent of two aerosols worth.  I've never finished a guitar with rattlecans, but I'm pretty sure it would be many more than that. 

So all in all I'm pleased with the result (but the next one is going to be Danish Oil, which I can do on the kitchen table😂😁).

 

And some photos.....

 

 

 

Edited May 18, 2019 by honza992

[DoubleOhStephan]

Looks lovely, fair play 👍🏻

[Andyjr1515]

Looks beautiful, @honza992

I would never have thought it was possible.  Well done

[rubis]

That looks a very smart guitar, beautiful finish 

[Jabba_the_gut]

Very nice indeed!

[TheGreek]

Very nice....love the all gold/brown colour palette

[SpondonBassed]

Beautiful job.

[ezbass]

👏👏👏

[Cuzzie]

Big thumbs up and bravo from me

[walshy]

Beautiful that mate 👍

[songofthewind]

Wow, that’s lovely. It works together very well. You are a real craftsman.

[Unknown_User]

That looks fantastic.  I love the spalted woods anyway but that really is very nice.  What wood was the back of the body made from?

Would you be able to talk through the process you used to grain fill and what went wrong with it?  It's something I'm looking into at the moment and the only method I know of is using oil/sanding dust slurry.

[Manton Customs]

Nice work :). Never tried brushing it!

In case you haven’t already figured out what went wrong with the grain filling, it’s not you...it’s aquacoat. I’m surprised they get away with selling it, it’s really ineffective at filling grain and worst of all it shrinks like crazy. Which is a shame as I loved the idea and how easy it should be to use, but I’ve given it a fair trial on a number of builds and every time it’s disappointed. Get some z poxy instead, not as easy to work with but is totally stable. The RF thixotropic grain fillers work well also, not quite as effective as the z poxy, but a bit quicker.

[honza992]

All, thanks so much for your comments.  This one took a long time to finish, especially the finish😬, so it means a great deal to me that you like it..👏👏

@Manton Customs Thanks for advice re grain fill.  And yes, it's really annoying that something like Aquacoat is marketed in that way.  I've tried it multiple times using different application techniques, and never get anything other than rubbish results.  And it 'ain't cheap.....  Thanks for the advice re Zpoxy.  I've tried West Sytems (which I use a lot for gluing) in the past with varied results. I should probably give it another go.  

@Unknown_User  Grain fill is one of the those things that sounds easy, but most people seem to find pretty difficult.  As far as I understand it, the basic options are:

1.  Sand and slurry with truoil or similar.  This works pretty well in my experience, but is messy.  Ideal if you are using truoil as a topcoat.  I'm not sure how compatible it is with other finishes.  I think @Andyjr1515 uses it under oil based varnish, and I use waterbased polyurethane over tru oil when I am burying my logos.  

2.  Paste filler like Stewmac's Colortone (waterbased) or Rustin's Grain filler (oil based).  I've tried both and not had great luck with either.  I never seem to be able to sand back to a smooth finish while keeping the gunk in the pores.  But this is probably the most used grain fill technique.  

3.  Epoxy.  I've tried West Systems in the past, and @Manton Customs uses zpoxy, I imagine they're very similar. I'll probably return to this next time.  Epoxies are two part and you need to be careful that your ratios are correct otherwise curing can be a problem.  West System I've never had a failure with, but I have with Araldite and another one (forgetten the name though), and I'm pretty careful to measure everything out as accurately as I can.  Assuming you've got the ratios right,  it also dries rock hard so you want to get as much off the surface of the wood otherwise sanding flat is a right pain. 

4.  Endless other options - egg whites, shellac, etc etc etc 

Like all of guitar building, you probably need to go through a few of these to see what works for you.  I'm still searching for the easy and failsafe answer to grainfill.  If I find it, I'll ket you know.  And by next year I'll be a millionaire......

 

 

 

[honza992]

On 20/05/2019 at 09:50, Unknown_User said:

That looks fantastic.  I love the spalted woods anyway but that really is very nice.  What wood was the back of the body made from?

The back is one piece walnut.....

[Manton Customs]

I’ve used west systems before to grain fill also, but preferred the z poxy as its a bit easier to work with. It also sands much, much easier than WS which really helps when a few coats are needed.

Like Aquacoat its not cheap either but even the smallest quantity they sell should do a couple of basses.

[honza992]

8 minutes ago, Manton Customs said:

I’ve used west systems before to grain fill also, but preferred the z poxy as its a bit easier to work with. It also sands much, much easier than WS which really helps when a few coats are needed.

Like Aquacoat its not cheap either but even the smallest quantity they sell should do a couple of basses.

OK, that's interesting that you say it's easier to sand.  I'll give it a go.  Just out of interest, do you use the 5 or 30 minute? And do you sand back to bare wood?  Really appreciate the info!

[Manton Customs]

Grain filling sucks so if I can save some pain I’m happy to help! It’s the Z poxy finishing resin you want for grain filling, which only comes in one cure time and I think is 30 mins (so ideal). But it depends on the temperature where you work.

I sand back in between coats (it’ll take at least two) to bare wood then do a final thinned coat (with iso alcohol) to get an even colour. The final one is more like applying a wiping varnish. This works well if you’re using water based poly as the epoxy will pop/amber the grain nicely.

 

 

[honza992]

21 hours ago, Manton Customs said:

Grain filling sucks so if I can save some pain I’m happy to help! It’s the Z poxy finishing resin you want for grain filling, which only comes in one cure time and I think is 30 mins (so ideal). But it depends on the temperature where you work.

I sand back in between coats (it’ll take at least two) to bare wood then do a final thinned coat (with iso alcohol) to get an even colour. The final one is more like applying a wiping varnish. This works well if you’re using water based poly as the epoxy will pop/amber the grain nicely.

 

 

Quick follow up if you don't mind.  For grain fill I've been reading about microballons, do you use them, or just neat?

Edited May 22, 2019 by honza992

[Manton Customs]

Neat, I’ve not tried adding anything except colours....Which works if you don’t add too much.

[Geek99]

I used Rustinsand found it quite hard to get decent results - it sank badly 

[BassTool]

Beautiful work 😍👌

[Owen]

Wood is the best thing. 

[Jimothey]

On 08/06/2019 at 14:56, owen said:

Wood is the best thing. 

Oooohh errrr missus!! 😁 

[Owen]

11 minutes ago, Jimothey said:

Oooohh errrr missus!! 😁 

Behave!