Using shellac for sealing top

Dave Olds · Post by **Dave Olds** » Tue Mar 31, 2009 5:29 am

I have seen many references to sealing a top with shellac prior to cutting binding channels, or to stop CA wicking into end-grains when installing rosetts and bindings - which all makes good sense to me.

What kind of shellac do you guys use. I have been looking here (NZ) and have only been able to find shellac flakes. Is there some kind of ready-made shellac available, or do I need to mix up my own. I have seen one reference to shellac in a rattle spray can, but can't find a source for this.

If not using a spray can, do you just brush the shellac on ?

Nick · Post by **Nick** » Tue Mar 31, 2009 5:58 am

Dave,Briwax make a shellac sanding sealer which I bought from Bunnys, it's a brush on that I use to seal the inside of the guitar before nailing the top on so I guess you could use on binding channels. I did use it once to seal the outside but wasn't very happy with how the topcoat lacquer stuck to it. I was probably doing something wrong, if you wanted to look into it maybe you could find out the best way to overcoat ? It was something I just had a try of which didn't work so I went back to how I've always done it, I must admit I didn't look into it too deeply.
Having said that, the oval rosettes I 'build up' out of multiple purfling strips around the soundholes on my Selmers are flooded with CA once they're in place. The soundboards are Sitka and I've never sealed the channel and never had a problem with bleeding into it. It might leave a bit of overflow on the top but once its all dry I scrape back the purflings and take a few shavings of the top and there's not trace of CA to be seen. As I say this is using Sitka Sounboards so is probably why I get away with it as it's a little 'tougher' than most.

Bob Connor · Post by **Bob Connor** » Tue Mar 31, 2009 7:28 am

This stuff is great.

sebastiaan56 · Post by **sebastiaan56** » Tue Mar 31, 2009 7:51 am

I use this stuff, http://www.thewoodworks.com.au/product/ ... C2326.html They seem to be the only vendor around here that carries Garnet, Ruby and Button Lac. Its easy (and much cheaper) to mix your own but if you are not into it there is always http://www.ubeaut.com.au/dewaxed.html

Just be aware that the premixes have a limited shelf life, flakes have years of shelf life if they are not temperature or humidity abused.

Rod True · Post by **Rod True** » Tue Mar 31, 2009 11:29 am

bob wrote:

This stuff is great.

Bob, you don't really use the Traditional finish and sealer do you? That isn't the wax free stuff.

You want to get the Zinsser's universal sanding sealer as it's 100% wax free

If you can't get this stuff, just mix it up. You'll know it's fresh and you won't (knock on wood) have any issues (with the shellac anyway).

Dave Olds · Post by **Dave Olds** » Tue Mar 31, 2009 4:42 pm

Thanks for your replies ....

Rod, before I saw your post I had trundled off down to Bunnies and found some of the Zinsser traditional shellac that Bob had recommended - and grabbed a small can.

What issues am I likely (possible) to have with the fact that this is not 100% wax free ? FYI, I am planning on finishing the guitar with French Polish ( but haven't got as far as the recipie for that as of yet ).

At this stage I will be using the shellac as a sealer for the purfling channels. I had cut the binding channels and they were a bit furry for my liking. I had a new router bit, but I believe it has a slight up-cut to it. I have now purchased one of the LMI binding router bits with a 5% downcut, but figured anything else I could do to get a better cut was worth the effort.

Thanks again[/i]

kiwigeo · Post by **kiwigeo** » Tue Mar 31, 2009 5:04 pm

David you might as well get the shellac youre going to use for the french polish job. Just make up a 2lb cut with the flakes and IMS meths (100% meths ie no water) and then cut it back to 1lb cut for sealing up prior to routing/CA gluing.

For FP I use blonde shellac flakes....LMI shellac is good but I also use locally sourced flakes here in Adelaide Australia. Dont use the amber stuff you buy at Bunnings or Mitre 10 unless you want an orange guitar.

To minimise tear out in your binding channels watch the direction you run the router. Check out Stewmac website or catalogue....theres a diagram showing direction and order of cuts. I use a spiral downcut bit in a Luthier Tools binding cutting jig to also help reduce tear out. If theres a bit of fuzz still then run arround with a piece of 120 grit sandpaper to clean out, again watching direction you run the sandpaper.

Cheers Martin

Rod True · Post by **Rod True** » Tue Mar 31, 2009 5:29 pm

Wax in a seal coat will not help the next coats adhear to it. Also, wax isn't going to be good in you binding channel, as glues do not like to stick to wax. Wax bad!

As Martin already said, just mix up fresh from flakes. It's really very easy and you only have to wait overnight before you can use it.

James Mc · Post by **James Mc** » Wed Apr 01, 2009 5:31 am

Hi Dave
Most art supply shops carry clear shellac in spray cans but it is hellishly expensive. Iâ€™ve played with a few of the ready mixed shellacs over the years and never been impressed by them, most seem to have high wax content.

If you are going to French polish the guitar then you may as well buy the shellac now and mix a small amount as sealer and store the rest until you need it. In an airtight container stored in a cool place, dry shellac lasts for years. I usually keep a well sealed bottle of mixed white shellac in the fridge, gets used for a remarkable number of things (my flat mate likes it as a clear gloss coat over her nail varnish and the better half uses it as a sealer over her paintings and as a pre coat to show flaws and features she may want to incorporate or avoid when she is carving stone). The mix I use for this general purpose handy bottle is 50g of dewaxed white shellac to 275ml of the water free metho. There isnâ€™t much difference between super blonde and white shellac, the white is a little harder and a little clearer. It could be my imagination, but the blonde seems a little more forgiving when applying.

The water free industrial methylated spirits is a new thing for me, Iâ€™ve always just used the normal stuff from the hardware store, canâ€™t say that Iâ€™ve noticed any difference. The other new thing Iâ€™ve tried recently is dropping the 10% sandarac from my French polishing mix (I ran out), but Iâ€™m sure that itâ€™s not smoothing as well when Iâ€™m pulling it over or building with as much lustre as it usually does.

I buy my shellac and other polishing supplies mail order from Goods and Chattels, Jim is one of those super helpful people you find far to few of these days. There are a few companies in Australia that do mail order and I donâ€™t think it costs much for a prepaid post pack to NZ, so ordering it from a company here may be your best option if you canâ€™t find any locally. It doesnâ€™t pay to scrimp on the shellac, better to buy good quality from a proven supplier. It all looks much the same as dry flakes, but anyone who has hit a bad batch can tell you how frustrating it can be trying to get a good finish with it.

Cheers
James

Nick · Post by **Nick** » Wed Apr 01, 2009 5:48 am

James Mc wrote: Iâ€™ve played with a few of the ready mixed shellacs over the years and never been impressed by them, most seem to have high wax content.

That explains the problems I had

Thanks everyone, you've helped this old fool as well as Dave.

Craig · Post by **Craig** » Wed Apr 01, 2009 8:27 am

Dave and Nick, If the shellac mix is left to stand , the wax will separate itself from the mix . You can then pour it off.

100% Alchohol seems difficult to obtain . In any case, it soon picks up water from the surrounding air and becomes 95%

Methylated Spirits bought from the store is 95 % and does the job fine.

kiwigeo · Post by **kiwigeo** » Wed Apr 01, 2009 8:58 am

Normal meths can be used and alot of people dont have any problems with it. I use IMS grade meths which is actually not that hard to find if you know where to look.

A few more comments about FP from my experiences

Make sure the oil you use is fresh and doesnt contain preservatives or other additives. I was using extra virgin olive oil but have just switched to pure walnut oil.

On my last guitar I had contamination issues which I pinned down to either the tack cloth or the sterated non-clog sandpaper I was using to prepare the wood prior to finishing. Ive since stopped using a tack cloth and am sanding with garnet paper.

sebastiaan56 · Post by **sebastiaan56** » Wed Apr 01, 2009 9:15 am

kiwigeo wrote:Make sure the oil you use is fresh and doesnt contain preservatives or other additives. I was using extra virgin olive oil but have just switched to pure walnut oil.

Most food oils cantain a greater or lesser degree of Vitamin E as a preservative (stops rancidity) but Extra Virgin Olive Oil shouldnt. (BTW how do they make extra virgin olive oil? they use extra ugly olives

) Raw oils dont, you know the health food shop ones.

Car detailing supply shops carry high purity solvents. If i remeber correctly, once I bought the tin it was the same as the Bunnies price.

James Mc · Post by **James Mc** » Wed Apr 01, 2009 9:57 am

I've been using Deer brand non loading aluminum oxide open coated electro coat stuff (kind of greyish white) from the the local hardware. I wouldn't have a clue if it is sterated or not but I haven't had an issue with it.

Iâ€™ve tried a heap of vegetable oils over the last 20 years and found the thin ones like peanut oil didnâ€™t work as good as the thicker ones. Then a few years ago a friend asked me to FP a harp heâ€™d had made from Macadamia wood (gorgeous stuff) so naturally I used Macadamia nut oil. It worked great and Iâ€™ve stuck with it ever since.

kiwigeo · Post by **kiwigeo** » Wed Apr 01, 2009 11:12 am

James, Im using the white no-load paper and I believe it has zinc stearate in it. Rick Turner has had issues with zinc stearate.

The current guitar Im working on has been sanded back with garnet paper and Ive avoided using the commercial tack cloths Ive used up to now.

Cheers Martin

Nick · Post by **Nick** » Wed Apr 01, 2009 11:25 am

Craig wrote:Dave and Nick, If the shellac mix is left to stand , the wax will separate itself from the mix . You can then pour it off.

100% Alchohol seems difficult to obtain . In any case, it soon picks up water from the surrounding air and becomes 95%

Methylated Spirits bought from the store is 95 % and does the job fine.

Thanks Craig, fortunately I work in the Chemistry department at the local University so laying my hands on some ultra pure, 100% alcohol is not a problem! Hic* (Why's my eyesight going?

)

James Mc · Post by **James Mc** » Wed Apr 01, 2009 12:01 pm

Hi Martin
I've used the white stuff for the final sanding of the guitar I just finished and far the shellac has gone on fine. I keep and eye on it and let you know if it goes wrong down the track.

I've never used the commercial tack cloths having been warned off them years ago by a mate who runs a furniture restoration shop. He doesn't trust them because some used chemicals that are incompatible with shellac and most don't list what is in them. All I use is a lint free cotton rag wet with metho that has a good dash of shellac or gum resin in it, I let it dry a bit so it gets a little tacky before it use it.

The only real contamination problem I've ever had with shellac was with some totally pore free fine grained maple. The contaminated areas looked suspiciously like fingerprints of a size to fit me. I traced it back to my loving Mum, who came for a visit and secretly did me the good turn of spraying all my tools and anything with a moving part in my workshop with this great new fangle silicone lubricant to, as the can said "keep your tools looking good and sliding free without sticking or annoying squeaks".

sebastiaan56 · Post by **sebastiaan56** » Wed Apr 01, 2009 12:33 pm

Nick O wrote:I work in the Chemistry department at the local University so laying my hands on some ultra pure, 100% alcohol is not a problem! Hic* (Why's my eyesight going? )

And you can still write lucidly!

Nick · Post by **Nick** » Wed Apr 01, 2009 1:11 pm

sebastiaan56 wrote:And you can still write lucidly!

It's the only reason.....Should see my writing bee4 I've**Hic** had a cup... cupull

Bob Connor · Post by **Bob Connor** » Wed Apr 01, 2009 3:10 pm

Rod True wrote:
bob wrote:

This stuff is great.
Bob, you don't really use the Traditional finish and sealer do you? That isn't the wax free stuff.

You want to get the Zinsser's universal sanding sealer as it's 100% wax free

If you can't get this stuff, just mix it up. You'll know it's fresh and you won't (knock on wood) have any issues (with the shellac anyway).

Whoops.

Yes it is the Sanding Sealer that I use Rod. I didn't look at the pic too well.

And I don't reckon that it's any inferior to shellac that you mix yourself. Certainly not as a sealer to prevent cA from wicking into end grain.

Frank Ford rreckons it's OK for French Polishing which is good enough recommendation

Rod True · Post by **Rod True** » Wed Apr 01, 2009 5:10 pm

I agree with you Bob. I use the Sanding sealer for anything that gets CA glued. I also use it to seal the body before spraying lacquer. I have also used it on one guitar to french polish (but I suck at french polish) and it worked out OK. Personally, I like the stuff and it's even easier than mixing your own. Just check the bottom of the can for the freshest stuff.

Dave Olds · Post by **Dave Olds** » Thu Apr 02, 2009 5:36 am

Thanks guys.

Heaps of good stuff here to go on. I willl try to hunt down the Zinsser sealer for sealing the top. At the current rate of build I won't be FP until sometime later in the century

so will revisit all of this information then.

Dave

Taffy Evans · Post by **Taffy Evans** » Tue Apr 07, 2009 8:28 pm

I've just come across this thread.
I've just done a fair bit of reading up on shellac from papers and articals I saved over the years. I wanted to know what the shelf life is of shellac flakes.
What I found out was that when the flakes stop disolving in the metho its had it.
So, I thought ,that batch I used on my first guitar dated 1977 [and I still have] is possibly too old as it stopped disolving years ago. I've got to buy some more,damit.

John Maddison · Post by **John Maddison** » Wed Apr 08, 2009 1:08 am

bob wrote:

If you can't get this stuff ...

Hi Bob - where from in Oz?

Bob Connor · Post by **Bob Connor** » Wed Apr 08, 2009 6:29 am

Have a look here John

http://www.zinsser.com.au/html/Zinsser_Where2Buy.htm

Australian/New Zealand Luthiers Forum

Using shellac for sealing top

Using shellac for sealing top

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