Home Brew Shellac

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NomadNomad Frets: 508
edited October 2017 in Making & Modding

My supply of Zinsser amber shellac is running low, and appears to be getting a bit old, so I've decided to see if I can make a replacement from raw ingredients. I want to do it this way for a few reasons...

  • Zinsser amber shellac is hard to find in the UK, although there are possible alternatives available here.
  • Shellac in liquid form has a limited life (it becomes less likely to cure fully).
  • Home brew should work out cheaper than buying the stuff ready-made.
  • Small batches can be made up, thus helping to ensure that the stock of liquid shellac remains fresh.

After some reading online, I opted to get some Liberon button shellac, which is described as giving a golden brown colour when made up into a liquid. If it turns out that this doesn't give the right colour, I'll look into getting a different shellac (lighter or darker, as the case may be) with a view to either trying that on its own, or mixing it with the button stuff.

For the solvent to make up the liquid, methylated spirits is often suggested, but the stuff stinks. Since meths is almost all ethanol with a bit of methanol to make it nasty (to drink), I decided to use bio-ethanol instead. I've already been using this for cleaning the brushes used for applying shellac, and it works just fine. It pongs far less (it has its own smell, but is rather more tolerable). I use the La Hacienda branded stuff from B&Q (used in those decorative fires), which costs £6 for two litres (or currently £13 for three 2L bottles - £2.17 per litre). It also works well as a general purpose cleaner and degreaser, and can be used in camping stoves that run on meths, all without ponging like meths. The La Hacienda bottle states that the stuff is at least 95% ethanol, which should be fine - apparently, it should be at least 90% for making shellac.

The plan is to make a 2lb cut, which indicates the ratio of shellac to solvent - 2lbs of shellc to a gallon. When crunched down to a sensible quantity, that works out to 50g of shellac to 250ml of solvent. If it turns out that it's too thick or thin, more shellac or more solvent can be added to change the cut. Traditionally, shellac is initially made up as a 3lb cut, and is usually reduced somewhat for use (1.5-2lb for coating, or a 1lb cut for sealing). (Liberon recommend mixing the 250g bag with 1L of solvent, which works out to a 2.5lb cut.)

The 250g bag of shellac cost £11 from Rest Express, so my 250ml of 2lb cut should work out to about £4.50 - about half the price of typical commercial offerings in liquid form.

Dry shellac usually comes as smallish flakes, but the Liberon button shellac was in the form of small discs, which can be seen here...

https://imgur.com/YU64Sdb.jpg

I had planned to mash them up with the pestle and mortar, but quickly found that this wasn't going to work readily - they're really hard and brittle. So I broke them up with a hammer (put disc on block of wood, and skelp another bit of wood while using hand to try and stop the bits from flying off), and got smaller lumps...

https://imgur.com/Ncz2D8o.jpg

The lengths of the edges range from 10-20mm (the discs are about 40mm or so in diameter). These were then bunged in a jar containing the 250mil of ethanol...

https://imgur.com/y8Cmz5h.jpg

Not much to see, really. The liquid already had some colour in it because the jar had been used for the brush cleaning ethanol (the staining indicating that it was indeed removing shellac from the brush), which has now been tipped into a second jar that had more ethanol in it. The other jar in the photos contains what remains of the Zinsser amber shellac (about 70ml or so).

Apparently, it takes about 24 hours for the stuff to dissolve, with a few shakes and stirs along the way, so I'll update on that. I dare say it might take a bit longer with this because the bits are somewhat larger than the flakes that other forms of shellac come as. I had a little look at it after about an hour, and the liquid had darkened a little and had become quite cloudy. I also found that the bits of shellac had stuck together and needed a stir to separate them, which suggests that they are dissolving (the surfaces soften as the solvent breaks them down, and they blend into each other).

A note about coverage on wood might be in order. When I had used the Zinsser to refinish my Blues Deluxe, it seemed that I had used hardly any. When I found out that the stuff has a shelf life, I started using it for finishing various wood projects around the workshop, generally a single coat with a light sand afterwards. On wood, it seemed to get used much faster. When the tin started leaking, I transferred what was left into jars, which allowed me to see how much I had left. I'm in the middle of building a tool wall, which is basically an 8x4' sheet of ply screwed to the wall. The whole outwards-facing surface was finished in shellac and took just about 250ml - that's an area of just under 3 square metres. Worth keeping in mind for when larger projects are in the offing.

It's also worth mentioning its behaviour as it ages in the tin. A few months ago, I made a toolbox-sized wooden drawer unit, and found that the drawers kept sticking, possibly because the shellac on the wooden runners was maybe a bit thick. Coats on larger flat surfaces were still okay - slap the stuff on, leave it for 20-30 minutes, and a light sand with a well worn foam sanding block resulted in a surface that felt smooth and non-tacky. It's only been in the last couple of weeks that I've noticed that the drawers in the toolbox pull out more easily now - there's still a tiny bit of tackiness at times, but it's almost gone. The Zinsser I have is now quite old (it was donated by @MtB just over two years ago, and I don't know how long he had it for before then), but some searching suggests anything from 2 to 5 years is about the limit before it starts to suffer from poor curing. So, some quite old Zinsser is still okay for flat surfaces, which probably means quite thin coats, but is borderline if it's applied more thickly (the features in the drawer runners were hard to get into to sand).

More anon...



Nomad
Nobody loves me but my mother... and she could be jivin' too...

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Comments

  • DeadmanDeadman Frets: 2580
    Absolutely amazing stuff and an interesting read.
    If however you ever need any fresh give me a shout and I'll send you some if you like. 
    Great work though. Hope it works out.
    My trading feedback is here 
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  • NomadNomad Frets: 508

    Thanks for the offer, @Deadman, but I'm specifically looking to try and come up with a recipe that gives a good substitute for the Zinsser amber. Given that my amp has already been tweedy mojo'd, I don't actually need amber shellac for the purpose of protecting my woodwork projects, but I do like the colour it produces. If anything, it's more about coming up with a recipe that works well as a substitute so that others can make up their own, rather than go through the hassle of trying to find Zinsser, or working through various bottles of possible alternatives.

    The button shellac has all but dissolved now - about a teaspoonful of gloop in the bottom of the jar. Took more like 2.5 days, which was not unexpected, given that it was pretty lumpy at the start. The bio ethanol certainly seems to work. The smell from the jar is actually quite pleasant - a bit like caramel or toffee.

    In the jar, it's a completely different colour from the Zinsser amber (on the left here)...

    https://imgur.com/jbD2oNc.jpg

    And, when coated, produces something that is noticeably paler...

    https://imgur.com/WCBknhr.jpg

    That's a single coat of each. The actual colour looks pretty similar, if maybe a tad more yellow, but it would take additional coats to get close to the Zinsser, which isn't what I'm looking for. It's worth noting that the Zinsser may be a more dense cut than the 2lb for the button, either when it was made, or possibly due to some evaporation within the tin over the years (it was about half a tin when I got it). However, I don't think that would account for the marked difference in colour when coated - something which tends to be backed up by the difference in colour of the actual liquids.

    Two possible options at this point: try the garnet Liberon flakes, or look into using an alcohol based stain. The garnet is described as producing a dark brown colour, and looks to be the darkest offering from Liberon. I'd be cautious about using a stain - reading suggests that it will mix fine if it's alcohol based, but there's a small risk that it could fade over time. I'd also prefer to keep the recipe as simple as possible.

    So, in terms of finding a Zinsser substitute, the Liberon button shellac doesn't do it, although it could conceivably be used to produce a lighter tint on a tweed amp, or as a way to build up to a darker colour over several coats. For me, I have the option of a paler shellac for some woodwork projects, so by no means wasted (and the flakes still in the bag will last indefinitely).

    I think my next step is to try the Liberon garnet flakes.


    Nomad
    Nobody loves me but my mother... and she could be jivin' too...

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  • NomadNomad Frets: 508
    edited October 2017

    I think it's worth giving Rest Express a mention...

    https://www.restexpress.co.uk

    First time I had ordered from them - I got the button shellac and some other stuff. The prices were very good, and the cheapest delivery option turned up quicker than expected. The bag of shellac flakes and delivery would work out to about £15 total, which is better than almost anywhere else unless you can find the flakes locally (£14 seems to be the norm, compared to £11 at Rest Express). Also got a 473ml/16oz bottle of Titebond Original for £5.75 - 7 quid at Axminster.

    They seem to specialise in wood finishes for the most part. The Tools menu is almost entirely Mirka sanders and kits, and they have a wide range of abrasives as well.

    Nomad
    Nobody loves me but my mother... and she could be jivin' too...

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  • ChalkyChalky Frets: 5440
    Can shellac be used on guitar bodies?
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  • WezVWezV Frets: 8901
    I don't think I have ever used a prepared shellac, always preferred to do it the proper way.  

    Same with hide glue, where they add stuff to make it usable st room temp and give longer life.... removing the main benefits of hide glue

    Shellacs real strength is that it's compatible with just about everything.  It makes a good sealer coat when dealing with potentially contaminated wood.  You can wipe, spray or brush it on and it's dry and ready for sanding level very quickly.

    its weakness is obviously water and alcohol resistance
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  • NomadNomad Frets: 508

    I've only used it for a tweed amp tart-up, and as a general sealer or protector for bits of wood around the workshop (nothing fancy - just jigs and things like the tool wall I'm currently making). For the most part, just a single coat with a light sand afterwards (it seems to raise the grain). It tacks up very quickly as the alcohol evaporates (a couple of minutes, if that), and seems to be touch dry in 20-30 minutes.

    It can be built up, although technically it doesn't form layers because it dissolves in alcohol - each new application dissolves a little of the dry surface it goes onto, so you get something more like an amorphous single layer.

    It also contains natural waxes, which can apparently cause adhesion problems when used as a sealer - some paints and the like can delaminate. There are dewaxed versions of shellac which can be used instead, although they tend to be somewhat bleached as well (which is probably desirable for a sealer). I haven't seen much in the way of the darker colours in a dewaxed version (although I'm sure I saw some on a US web site somewhere).

    Nomad
    Nobody loves me but my mother... and she could be jivin' too...

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  • NomadNomad Frets: 508
    edited October 2017

    The Liberon garnet shellac has arrived. Unlike the button, this is finely broken up into little flakes...

    https://imgur.com/EoJFp09.jpg

    There was very little clumping, and the bits that there were broke apart pretty easily. Here it is in the jar just after adding the ethanol...

    https://imgur.com/ePPI8xM.jpg

    Same proportions as before: 50g shellac to 250ml of ethanol for a 2lb cut.

    I expect this will dissolve a lot faster than the button. It also has a slightly different colour - the garnet has a reddish tinge (which is probably where the name comes from), while the button is more of a straight brown (like coffee with no milk in it). The colour of the dissolved button was unexpected, so it will be interesting to see how the garnet turns out.

    Nomad
    Nobody loves me but my mother... and she could be jivin' too...

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  • NomadNomad Frets: 508
    edited October 2017

    It's dissolving much more quickly than the button. After just over an hour, the granulated look above had given way to brown cloudiness with the clear ethanol above. With a quick shake, it all turned brown. A stir indicates that there are still some lumpy bits, but not much.

    Colour in the jar is a bit lighter than the Zinsser at the moment, but much darker than the button...

    https://imgur.com/L7R1avL.jpg

    I'm not sure how much darker it will get, but a quick swatch on a bit of blonde plywood suggests that it will be dark enough for adding the requisite mojo to a tweed amp. I'll see how it looks once it's all dissolved - if it's still lighter than the Zinsser, I might take half of it and add some more shellac to make it up to a 3lb cut. (As mentioned earlier, I don't know the cut of the Zinsser, and some evaporation of mine could mean that it's slightly denser now than when it was new.)

    Nomad
    Nobody loves me but my mother... and she could be jivin' too...

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  • TTonyTTony Frets: 14787
    Nomad said:

    The Tools menu is almost entirely Mirka sanders and kits, and they have a wide range of abrasives as well.

    As it happens, I've been looking for a decent price on some Mirka stuff.  And they seem to have Mirka stuff at decent prices.
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  • NomadNomad Frets: 508
    The Abranet abrasive seems to have a good reputation - wears well and the mesh structure is very clog resistant and conducive to letting the sander's extraction draw the dust away. The sanders aren't exactly cheap, though. Not sure I can justify the cost for the amount of sanding that I do (and all my pennies are getting blown on lumps of beech at the moment).

    Nomad
    Nobody loves me but my mother... and she could be jivin' too...

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  • TTonyTTony Frets: 14787
    Don't want to derail your Shellac thread, but I used some Mirka / Abranet on a cabinet making course recently.  It's very effective, low-mess, and the abrasives are long-lasting.  The kit he was using was c£400 package but I'd just be looking at a manual kit.
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  • Thanks for sharing this @nomad been meaning to look into shellacing tweed cabs and this will give me a head start. Thanks!
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  • NomadNomad Frets: 508
    TTony said:
    Don't want to derail your Shellac thread, but I used some Mirka / Abranet on a cabinet making course recently.  It's very effective, low-mess, and the abrasives are long-lasting.  The kit he was using was c£400 package but I'd just be looking at a manual kit.

    Just been looking at the manual stuff - I didn't realise the blocks have dust extraction in them, which is a really neat idea. How did you find the electric sander to use in terms of fit in the hand, general comfort, and noise?

    Nomad
    Nobody loves me but my mother... and she could be jivin' too...

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  • NomadNomad Frets: 508
    Thanks for sharing this @nomad been meaning to look into shellacing tweed cabs and this will give me a head start. Thanks!

    Glad it will be of use. I need to do some tests to be sure, but my feeling is that the 2lb cut of garnet might be a little easier to control than the neat Zinsser for doing tweed. When I did my amp, I applied two coats straight from the tin, and the first was a little uneven. When I applied the second, I biased the brush to the lighter areas while it was wetter to help even things up. The overall result was quite dark (which I'm happy with).

    Before...

    https://imgur.com/Sawn4wk.jpg

    After...

    https://imgur.com/fuA6uEP.jpg

    The usual recommendation is to dilute the Zinsser a bit, at least for the first coat, and possibly less dilution for subsequent coats, to help control how dark it becomes, albeit at the cost of doing more coats to build up the colour. I only have wood to do tests on, but at a guess, I'd say three coats of the 2lb garnet would be needed to get a good match to two coats of the neat Zinsser. I just recoated my little swatch, and I would say that two coats of the garnet is of similar darkness to a single-coat Zinsser swatch (or maybe a shade darker), but I also note that it's a slightly different colour - a bit more orangey or amber compared to the Zinsser one, which looks quite brown on the bit of ply (which isn't how it looks on other bits of pale softwood - more amber on those).

    The garnet has almost completely dissolved, now - just some dregs sticking to the bottom of the jar. I'll do some more organised tests soon, and take some photos.

    Nomad
    Nobody loves me but my mother... and she could be jivin' too...

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  • NomadNomad Frets: 508

    Another little update. I split the 2lb cut of garnet shellac into equal quantities and added another 12.5g of flakes to one to take it up to a 3lb cut. Nearly all dissolved now, and here are the swatches I've been making...

    These are all unsanded - just painted straight on. As mentioned earlier, the Zinsser looks a bit darker and maybe a bit more brown on this plywood than it does on other softwood that I've been using it on. I don't recall what the Unknown swatch is - it could have been the 2lb garnet when it was partially dissolved. The three garnets are the main interest, though. As noted, the colour differs from the Zinssser in that it's a touch more orangey (or more like a proper amber on this wood). The 3lb garnet is surprisingly close to the two coats of 2lb garnet - just a shade paler, while the single coat of 2lb garnet is noticeably lighter. I'm wondering how a 2.5lb cut of the garnet will look, so I'll make up some of that from the 2lb and 3lb cuts (equal quantities of each).

    I'll sort out a bigger bit of the ply and do some proper swatches soon, covering slightly larger areas, and showing the effect of additional coats. One thing to consider about the above is that the control of the liquid wasn't as good as it would normally be because they were done with a brush that was starting dry. In other words, the jar of cleaning ethanol is basically very weak shellac, so the brush has shellac residue on it and is flexed in the fingers to remove the stiffness from the bristles. When it's like this, the initial dip isn't with a wet and flexible brush, so control of the fluid isn't as good - it's possibly going on a bit more thickly than it normally would when painting a larger area. For the proper swatches, I'll wet the brush in the cleaning jar first and get rid of the excess on a tissue, then dip and paint.

    Nomad
    Nobody loves me but my mother... and she could be jivin' too...

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  • TTonyTTony Frets: 14787
    Nomad said:

     How did you find the electric sander to use in terms of fit in the hand, general comfort, and noise?
    Amazing piece of kit.

    Fits really comfortably in the hand, is lightweight and the "on/off" switch is the top of the unit, so you turn it on as you pick it up (which was a bit disconcerting at first).

    There's little transfer of vibration to the hand/arm, so I could use it comfortably for much longer than my own random orbital sander.

    It's also much quieter.

    And very effective.  Don't leave it static in any one place for any more than a second or two
    ;)

    It's expensive, but if you're doing a lot of sanding work, I'd say it's worth it.
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  • NomadNomad Frets: 508
    Cheers, Tony - it sounds like the gear to get (if my sanding activities ever justify it). Ben Crowe at Crimson speaks highly of them as well.

    Nomad
    Nobody loves me but my mother... and she could be jivin' too...

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  • NomadNomad Frets: 508

    Back to the shellac.

    I made up some swatches for comparison, using the four shellacs I have, each with 1, 2, 3 and 4 coats...

    The most noticeable thing is that the 2lb cut button shellac is much paler than the others. (A bit of jiggling about indicated that 4 coats of this was roughly equivalent to 2 coats of the Zinsser in terms of value - how light or dark a colour is.) The difference between the two cuts of garnet is quite subtle with one or two coats - very hard to tell, even side by side. If you were using loads of the stuff, you could probably economise by making up a 2lb cut without there being much difference in the end result.

    As noted previously, the Zinsser still came up with a slightly different hue. Here it is between the two garnet cuts for a side by side comparison...

    Value is pretty similar, suggesting it's also around a 2lb to 3lb cut. The hue is still a touch more brown than the garnet (or is biased slightly towards green if we take the garnet as a starting point). Bear in mind that this is on pale softwood-faced plywood, and not tweed - the light colour in tweed is a bit darker and maybe more yellow than this, which will influence the resulting colour when the transparent shellac is added - it would be harder to tell the difference between the shellacs. The dark parts of the tweed will dominate the result and would likely mask the difference between garnet and Zinsser to the extent that it would be very hard to tell which was which.

    A few things to note...

    There was no sanding between coats, both because a coating on tweed won't get sanded, and because sanding could add a variable to the comparison. Even so, there will still be differences due to brushing out manually.

    The Zinsser is quite old, and could be a slightly denser cut due to evaporation than would be found with a new tin.

    The Zinsser took a bit longer to cure than the fresher shellacs. The coatings were done in the order shown in the picture of the four strips. Even after leaving them for a while to dry, I came back to find that the Zinsser was still tacky while the subsequent strips were dry enough to recoat. It did go off eventually, though.

    To get a clear edge to each swatch, I put a bit of masking tape across the wood on the side towards the label, and painted away from the tape with all strokes. Even so, there was still some seepage under the tape.

    Due to the lighting, I had to take the photos at an oblique angle to avoid reflections, which will result in the swatches further from the camera being marginally darker than the nearer ones. When I next have my oil painting gear set up, I can try the photos again using the easel lighting (which is daylight balanced, very even, and should allow the camera to be perpendicular to the swatches).

    There was only limited processing of the images: a crop and resize, resetting the colour balance using the white paper as the reference, and a tweak to contrast and shadow density (same adjustment of these applied to all photos). No sharpening.


    In conclusion, it's clear to me that the two Liberon shellacs do not match the colour of the Zinsser (while the button and garnet are a close match to each other in terms of hue). It would be interesting to try other brands of shellac in solid form to see how they compare. Another possibility is to try adding some spirit-based/soluble dye to the garnet to try biasing the colour a little, but it would be important to find a dye that doesn't fade adversely. In terms of a coating for lacquering tweed, it's perhaps debateable whether it's really necessary to get a perfect match to Zinsser, although it's hard to be sure without trying the Liberon shellac on actual tweed. Given that the tweed as a background will mask the differences to some extent, it may well be the case that it will look fine in isolation, and only appear to be different with a side by side comparison.

    Nomad
    Nobody loves me but my mother... and she could be jivin' too...

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