Refinishing alternatives to nitro

[LawrenceH]

Hello
I've had a bit of fun recently doing spot repair in the natural finish in my Jap 75RI which makes me wonder about doing a complete refinish on a different instrument. From reading around it seems that while you can get a refin done professionally, allegedly using polyurethanes/polyesters especially for instruments, the guitar specialist shops only sell nitro-based lacquers.I don't want a nitro finish, I'd like something more durable (not really into the whole relic'ed thing).
So...
If I wanted to use polyurethane, where if anywhere would I get it from? I'd like a reasonably thin finish that could be polished up to a high gloss, preferably in an aerosol as these are allegedly safer than the two-part stuff, plus I really don't want to have to muck around with spray guns.

Finally, one finish I'd really like to try is Candy Apple Red, which I understand is a tinted red plus clear coats on top of either silver or gold metallic. Is this achievable with polyurethane?

EDIT: Also, if there are any other alternatives I should consider like acrylic, how durable are these?

Edited June 26, 2010 by LawrenceH

[henry norton]

The main reason nitrocellulose is so handy for spraying things like guitars is because it can be packed into an aerosol and it won't kill you if you breathe in the fumes, neither of which can be said about polyester which needs to be mixed with a catalyst and then thinned just before it's sprayed on so it can't be packed into an aerosol. The health issues aren't meant to be as bad as they used to be - you needed a proper spray booth and an air fed mask as a simple filter wasn't enough - but it's still not something you'd want to breathe in.

I don't know much about polyurethane lacquer (allot of the big makers use it now, allegedly) but I've been using acrylic to finish allot of my necks recently as it's fairly tough but goes on quite thin and shows the grain up nicely but I've never tried it over a colour base. You can do a metalflake finish with just about any spray lacquer so polyurethane shouldn't be a problem but don't discount cellulose because it doesn't go on as thick as 2 pack - the reason most cellulose finishes on guitars look worn out is because they're old, not because cellulose is soft - it isn't.

[LawrenceH]

[quote name='henry norton' post='878765' date='Jun 27 2010, 12:32 PM']The main reason nitrocellulose is so handy for spraying things like guitars is because it can be packed into an aerosol and it won't kill you if you breathe in the fumes, neither of which can be said about polyester which needs to be mixed with a catalyst and then thinned just before it's sprayed on so it can't be packed into an aerosol. The health issues aren't meant to be as bad as they used to be - you needed a proper spray booth and an air fed mask as a simple filter wasn't enough - but it's still not something you'd want to breathe in.

I don't know much about polyurethane lacquer (allot of the big makers use it now, allegedly) but I've been using acrylic to finish allot of my necks recently as it's fairly tough but goes on quite thin and shows the grain up nicely but I've never tried it over a colour base. You can do a metalflake finish with just about any spray lacquer so polyurethane shouldn't be a problem but don't discount cellulose because it doesn't go on as thick as 2 pack - the reason most cellulose finishes on guitars look worn out is because they're old, not because cellulose is soft - it isn't.[/quote]

Thanks for the helpful reply. So would you know where I could get the acrylic sprays from? And how much if at all acrylic yellows with age?

[mrjim]

I've successfully finished home builds using acrylic aerosol paints as well. Go to your local halfords and you will be able to get good variety of colours to choose from. I found halfords to be a bit more expensive than my local auto shop (£7 vs. £3 for the same stuff) but I was only after black paint which is more likely to be stocked by the smaller independents.

All of the paints I used claimed to include UV inhibitors which are supposed to stop the paint from yellowing (I don’t know if you can buy them without. I couldn’t see any).

I would recommend spraying about 4-5 colour coats then spraying at least 12 topcoats of acrylic clear. You need to spray so many coats because when you come to buff and polish the paint, you’ll take off quite a few players of paint. I managed a nice glassy finish using this method.

Metallics are a bit harder than plain colours. Rather than explain it all, your best source of info would be to browse though the rerannch forum:

[url="http://reranch.com/reranch/"]http://reranch.com/reranch/[/url]

Although they deal with American products and talk about using nitro, the principles are the same.

If this sounds like too much work try asking your local car sprayshop to spray it for you (if you have one!). I know people who have had success this way

Edited June 27, 2010 by mrjim

[mrjim]

Also if you are going to strip the existing finish back to the bare wood then depending on the type of wood, you may need to grainfill and then apply sanding sealer to stop your finish sinking into the wood.

Edited June 27, 2010 by mrjim

[LawrenceH]

[quote name='mrjim' post='878804' date='Jun 27 2010, 01:34 PM']...talk about using nitro, the principles are the same.[/quote]

Thanks, yes that's what I was wondering. Good to hear you can get a glass-like finish. Do you sand between coats or do most/all of that after the final clear coat?

Regarding grainfilling/sealing, I'm hoping that I can strip leaving those layers below, but if I have to do it then I'm up for having a go. Thanks for taking the time to give such a useful reply, much appreciated!

[wesfinn]

all laquers and paints are harmful if you breath in the fumes especially nitro so make sure that you do what ever you are doing in a well ventilated area and wear a mask with organic filters suitable for paint vapours.

You can buy waterbourne laquer from tonetechluthiersupplies.co.uk they can supply lots of paint types tho if you want poly you will need a gun and compressor to apply it.

[Mikey R]

Ive been researching finishes too, have you considdered either an oil finish or a wipe on varnish?

Ive been readingup on General Finishes, either oil based or water based. From looking at their website, theyre look really easy to apply if you follow the instructions.

You need to look out for the oil based varnish as the rags can spontaeously combust (!) if you dont let them dry flat, theres instructions on the website on the safe way to do this.

[url="http://www.generalfinishes.co.uk/"]http://www.generalfinishes.co.uk/[/url]




I might get some of the satin in and try it out, I'll let you know how I get on if I do.

Then theres the oil finishes like Danish oil, Ive not looked at these too closely yet.

[henry norton]

I always thought oil type finishes looked better on natural wood guitars than a thick, glassy smooth lacquer. That said, you'd be hard pushed to get a metalflake finish using oil

Have you looked at brush on finishes like Rustins plastic coat [url="http://www.axminster.co.uk/product-Rustins-Rustins-Clear-Plastic-Coating-23018.htm"]click here![/url] Bryan May painted his guitar with it and that still looks OK - give it enough coats and you'll be able to sand and polish it just the same as a sprayed finish but with considerably less mess.

[Bloodaxe]

[quote name='henry norton' post='879022' date='Jun 27 2010, 05:57 PM']I always thought oil type finishes looked better on natural wood guitars than a thick, glassy smooth lacquer. That said, you'd be hard pushed to get a metalflake finish using oil

Have you looked at brush on finishes like Rustins plastic coat [url="http://www.axminster.co.uk/product-Rustins-Rustins-Clear-Plastic-Coating-23018.htm"]click here![/url] Bryan May painted his guitar with it and that still looks OK - give it enough coats and you'll be able to sand and polish it just the same as a sprayed finish but with considerably less mess.[/quote]
+1 for Rustin's, and for brush-finishing.

Haven't tried their two-pack, looks interesting though.

I have used [url="http://www.rustins.eu/Details.asp?ProductID=833"]this stuff[/url] on a couple of necks & would do so again. Goes on like tar (even with a Purdy Sprig Elite) but flats out superbly & takes a lovely polish with a coarse cloth and some old gunky Brasso. Seems durable too, claims to be non-yellowing but far too early to tell (only been on a year).

Not impressed by either Plastikote or Holt's Duplicolor clear rattle cans - not very hard wearing & prone to bruising even after a couple of months curing time. Holt's Matt Black was good though.

If the existing finish isn't lifting or doing anything suspicious, why not just skim-fill it, key it up & then apply a new finish over the top? Saves doing all the prep work again.

Pete.

[LawrenceH]

[quote name='Bloodaxe' post='879072' date='Jun 27 2010, 06:40 PM']+1 for Rustin's, and for brush-finishing.

Haven't tried their two-pack, looks interesting though.

I have used [url="http://www.rustins.eu/Details.asp?ProductID=833"]this stuff[/url] on a couple of necks & would do so again. Goes on like tar (even with a Purdy Sprig Elite) but flats out superbly & takes a lovely polish with a coarse cloth and some old gunky Brasso. Seems durable too, claims to be non-yellowing but far too early to tell (only been on a year).

Not impressed by either Plastikote or Holt's Duplicolor clear rattle cans - not very hard wearing & prone to bruising even after a couple of months curing time. Holt's Matt Black was good though.

If the existing finish isn't lifting or doing anything suspicious, why not just skim-fill it, key it up & then apply a new finish over the top? Saves doing all the prep work again.

Pete.[/quote]

I'm a little wary about compatibility when mixing different finishes. That's a real shame about the Plastikote, I was looking at that and thinking it might be a decent option - do you remember which you tried? Their drying times are very fast, I'm surprised it's still a problem so far down the line.

[Bloodaxe]

[quote name='LawrenceH' post='879135' date='Jun 27 2010, 07:34 PM']I'm a little wary about compatibility when mixing different finishes. That's a real shame about the Plastikote, I was looking at that and thinking it might be a decent option - do you remember which you tried? Their drying times are very fast, I'm surprised it's still a problem so far down the line.[/quote]

Drying time & Curing time are different animals.

If your 75RI is already finished in Poly, then there should be no real issue with adverse reactions from any refinishing. Poly coat is catalysed, so it chemically cures in next to no time. The only way to get it off is with a sander, chisel or a [b]lot[/b] of Nitromors (preferably the lethal yellow version) & steel wool. The Rustin's brush-varnish will go on over any painted finish with no adverse effects at all, but it does need to be "keyed in" to the surface it's being applied to and it's always a good idea to key in all coats from primer up to final varnish to ensure good adhesion (almost irrespective of the paint system you're applying).

Can't remember the exact flavour of PlastiKote that I had a problem with, but after the spray can issue one of their so-called Fast Dry Enamels (in the little jars) caused an annoying setback on a Signwriting contract a few years ago which was enough to put me off most of their products for life. The only exception is their range of metallic golds - I've had good results with those, but not applied them on anything that encounters heavy use.

For rapid drying brushing enamels with great covering power, I now swear by this stuff: [url="http://www.stonehouses.co.uk/product_list.php?id=332"]http://www.stonehouses.co.uk/product_list.php?id=332[/url] - I've not tried spraying it, but this type of paint usually goes through an airbrush with no trouble. If I ever refinish the SB-1000F again it'll be with a combination of airbrushed Cover-It & brush-applied Rustin's.

Pete.

[mrjim]

[quote name='LawrenceH' post='878848' date='Jun 27 2010, 02:24 PM']Thanks, yes that's what I was wondering. Good to hear you can get a glass-like finish. Do you sand between coats or do most/all of that after the final clear coat?[/quote]

I did not sand between coats. Just after the final clearcoat. You should be aiming to spray a lot of light coats anyway (this also helps with the curing process)

Edited June 27, 2010 by mrjim

[LawrenceH]

[quote name='Bloodaxe' post='879165' date='Jun 27 2010, 08:12 PM']Drying time & Curing time are different animals.

If your 75RI is already finished in Poly, then there should be no real issue with adverse reactions from any refinishing. Poly coat is catalysed, so it chemically cures in next to no time. The only way to get it off is with a sander, chisel or a [b]lot[/b] of Nitromors (preferably the lethal yellow version) & steel wool. The Rustin's brush-varnish will go on over any painted finish with no adverse effects at all, but it does need to be "keyed in" to the surface it's being applied to and it's always a good idea to key in all coats from primer up to final varnish to ensure good adhesion (almost irrespective of the paint system you're applying).[/quote]

The bass I'd be refinishing is a tatty black 80s MIJ - not sure of the finish yet as I haven't received it yet, but I'm guessing either polyurethane or polyester. If it's anything like as thick as the coat on the 75RI then I'll try and get at least some of it off, just out of curiosity over whether I can hear any difference in tone! On the 75RI chipping out the dings seemed straightforward, if a little time-consuming.
I understand I can put almost anything over the top of poly, but not sure about what works the other way round. Could I use an acrylic lacquer for my base colour and then coat with something like the Rustins or 2K, or will I get problems with shrinkage/adhesion/something else? From what I've read somewhere (posibly reranch?) you can't do this over a nitro base coat.

I'd not previously considered brush finishes. It seems an attractive option if the finish can be made reasonably thin. Ideally I want whatever is the most durable, so this might mean 2K(?)

Questions questions! I appreciate all the input so far, everyone's been very helpful thanks! When I get this project off the ground I'll post a thread in the Build Diaries section, for better or worse. I'm thinking Candy Apple Red with a matching headstock on a rosewood neck.

[henry norton]

Apparently (well, according to Ron Kern, a veteran US maker), in the golden Era, fender used acrylics (like Halfords aerosols) as solid colour coats, the clear coats were Nitrocellulose lacquer and that was sprayed on top of a catalyst activated primer/sealer.. the precursor to polyurethanes. So it looks like you can use just about whatever you like

[mrjim]

I would only use nitro with other on its own i.e. not mixing with other products; it will react with most things.

As far as acrylic goes it [i]could[/i] be overlaid with other products as it’s more stable - however there is no definite answer. If you were to take a chance I would test compatibility on scrap wood before spraying on a primed body.

As regards overcoating with Rustins or 2k stuff I would be cautious if you are going for a block colour. I know Rustins Plastic Coating uses an acid based hardener which can affect the underlying colour. I think people mainly use it for clear or stained finishes (e.g. Brian May’s guitar).

There’s no harm in experimenting as long as you use scrap wood but I’ve found acrylic finishes to be hard enough. You can still dent/chip an acrylic finish but I can also damage super thick poly finishes as well!

[LawrenceH]

[quote name='mrjim' post='880325' date='Jun 28 2010, 08:48 PM']There’s no harm in experimenting as long as you use scrap wood but I’ve found acrylic finishes to be hard enough. You can still dent/chip an acrylic finish but I can also damage super thick poly finishes as well![/quote]

My 75RI is testament to that...is there any brand of acrylics you'd recommend? Otherwise my digging around on the internet has led me to specialistpaints and their 2K aerosols, which look great, but as well as being expensive the toxicity is an issue. Also does anyone have an idea of quantities, in terms of ml, that'd be required for each layer?

[mrjim]

I just used the cheapest from the local auto shop which was a combination of Carplan acrylic primer and colour coats. I then had to use Granville acrylic clear as they didn’t have any carplan clear in stock!

Regarding paint volumes, if you read through the reranch 101

[url="http://reranch.com/101.htm"]http://reranch.com/101.htm[/url] and
[url="http://reranch.com/solids.htm"]http://reranch.com/solids.htm[/url]

It will explain it all in detail but it is basically one can of colour and at least 2 cans of clear (third permitting if you can afford it...) Just don’t spray a whole can in one go, I could get about 4-5 coats from one 400ml can.

[LawrenceH]

[quote name='mrjim' post='880453' date='Jun 28 2010, 10:29 PM']I just used the cheapest from the local auto shop which was a combination of Carplan acrylic primer and colour coats. I then had to use Granville acrylic clear as they didn’t have any carplan clear in stock!

Regarding paint volumes, if you read through the reranch 101

[url="http://reranch.com/101.htm"]http://reranch.com/101.htm[/url] and
[url="http://reranch.com/solids.htm"]http://reranch.com/solids.htm[/url]

It will explain it all in detail but it is basically one can of colour and at least 2 cans of clear (third permitting if you can afford it...) Just don’t spray a whole can in one go, I could get about 4-5 coats from one 400ml can.[/quote]

That's ace, I'd seen some of that stuff but wasn't sure on quantities compared to the nitro. Thanks again, the contributions on this thread have been a great help!

[Mikey R]

[quote name='henry norton' post='879022' date='Jun 27 2010, 05:57 PM']I always thought oil type finishes looked better on natural wood guitars than a thick, glassy smooth lacquer. That said, you'd be hard pushed to get a metalflake finish using oil [/quote]

Ok, a danish oil wouldnt work over paint, but the water or oil based urethanes would probably work just fine. I wonder if you can get a metallic water based paint, then go over with a red milk paint, and finish up with a urethanes based varnish.

From what Ive been able to find out, a polyurethane varnish is pretty much the same stuff as the laquer, the difference is only really how its applied, wipe or spray. That, and the two pack stuff cures differently of course, but Im not likely to use that stuff any time soon, so Ive not read much about it.

EDIT: I added the word "probably", like I said Ive never tried this so just musing out loud.

Edited June 29, 2010 by Mikey R