Shines hardened shellac - ratios

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Bob_H
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Shines hardened shellac - ratios

Post by Bob_H » Sun Nov 27, 2022 9:49 pm

Hi

I am looking for advice on the correct ratios for mixing denatured alcohol, shellac, and Shines shellac hardener.

The Shines product website https://www.shellac.net.au/shop/shellac ... ch-polish/ states that that hardener is calibrated for shellac solution mixed at a 4:1 ratio (Denatured alcohol to shellac) and that 41.75 ml of hardener is sufficient to make 250ml of hardened fresh polish.

Does this mean:

(1) I add 41.75 ml of hardener to 250 ml of shellac solution, so I end up with 291.75 ml of hardened french polish solution; or

(2) I add 41.75 ml of hardener to just under 210ml of shellac solution, so I end up with 250 ml of hardened French polish solution?

That is, is the ratio of denatured alcohol (mls): Shellac (grams) : Hardener (grams) meant to be:

4: 1 : 0.67 (example 1) or

4 : 1 : 0.80 (example 2)?

Or are these ratios so close as to make no real difference?

I will contact Shines next week to check, but thought I would ask here first in case I was missing something.

Also, when using the hardened shellac solution, is this used for all coats on the instrument (after pore filling) or only for finishing coats?

Any advice greatly appreciated.
Bob Holbert
Lyndoch

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lamanoditrento
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Re: Shines hardened shellac - ratios

Post by lamanoditrento » Mon Nov 28, 2022 8:43 am

Hi Bob,

The ratio of alcohol to shellac isn't significant. A 1:4 ratio just gives you a two-pound cut which is a good practical bench cut. After I mix a bench cut I will then cut it down further with additional alcohol depending on what I am doing. I french polish with something more akin to a 1/3 to 1/4-pound cut which would be around 1:16. The important ratio is a 1ml of harder to 1g of shellac.

Also remember that grams and ml are only interchangeable for water not alcohol or other liquids, alcohol weighs less than water for example.

My hard shellac mix normally looks like:

63gm shellac + 250ml of alcohol, once mixed then add 63ml of hardener (then sit for 3days before I use it).

I use hard shellac for the whole polish as it would be hard to tell what is what by the time everything is flat and buffed. It would be very easy to flatten or buff off or through just the last few coats.

You have about 3 weeks before the hard shellac starts cross-linking and being resistant to the alcohol. So if you can polish in that time the hard shellac shouldn't change your process. If it takes you longer than that, you need to deal with it a bit more like a lacquer as the previous layers won't melt/merge into each other.
Trent

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Bob_H
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Re: Shines hardened shellac - ratios

Post by Bob_H » Mon Nov 28, 2022 8:58 am

Thanks Trent - that's the sort of "hands on" feedback I was hoping for
Bob Holbert
Lyndoch

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kiwigeo
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Re: Shines hardened shellac - ratios

Post by kiwigeo » Mon Nov 28, 2022 10:46 am

Bob_H wrote:
Sun Nov 27, 2022 9:49 pm
Hi

I will contact Shines next week to check, but thought I would ask here first in case I was missing something.
The last time I contacted Shines someone other than Robert answered the phone and I spent alot of time explaining what I needed.....it was a bit frustrating. On previous occasions Ive talked to Robert and all questions got answered quickly.
Martin

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Re: Shines hardened shellac - ratios

Post by WilliamDavidReynolds » Fri Jan 27, 2023 2:33 pm

lamanoditrento wrote:
Mon Nov 28, 2022 8:43 am
. I french polish with something more akin to a 1/3 to 1/4-pound cut which would be around 1:16. The important ratio is a 1ml of harder to 1g of shellac.
So I’ve been gearing up for traditional shellac finishing, because it looks amazing and is def more shop friendly.
I’ve been looking at every shellac/French polish badass I can find etc etc,
This thread is a good one, so the Hardener makes the shellac more sustainable? More durable? Or is this a benefit for the shellac itself?
The only reason I’ve been not hastily ordering flakes is the durability aspect.
I learned Ken Parker’s method of epoxy and oil over the epoxy, and was thinking shellac over epoxy might be pretty good, not just epoxy pore filling but a rubbed on rubbed off coat like Ken does and shellac over?
Looks I just rambled out more questions than I started typing with.

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Bob_H
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Re: Shines hardened shellac - ratios

Post by Bob_H » Fri Jan 27, 2023 2:59 pm

WilliamDavidReynolds wrote:
Fri Jan 27, 2023 2:33 pm

... so the Hardener makes the shellac more sustainable? More durable? Or is this a benefit for the shellac itself?
The Shines website claims that when the hardener is added, the final finish is "much harder than an ordinary shellac finish. This coating withstands heat, water and alcohol". It takes a couple of weeks after application for the benefit to be realised.
Bob Holbert
Lyndoch

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kiwigeo
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Re: Shines hardened shellac - ratios

Post by kiwigeo » Fri Jan 27, 2023 4:12 pm

Okay a few thoughts from me:

1. Hard shellac generally has a hardener plus a plasticizer added. The hardener usually takes around 30 days to fully cross link and the plasticizer is there to stop crazing.

2. Hard shellac is much more durable than straight shellac. The downside is once the hardener has cross linked you cant carry out repairs by burning in new shellac. That said all of the instruments Ive finished with hard shellac have not shown any sort of wear and tear.

3. Pore filling. If you're using epoxy there are two approaches. You can aim to end up with a solid layer of cured epoxy at the end of the pore filling or alternately you can sand back so that the epoxy only remains in the pores. I do the latter. I started off using Zap epoxy and then switched to West Systems epoxy and now I'm using Boatcote epoxy with a thinner added. I also use a more traditional pumice and shellac pore filling method on some of my guitars.

4. French polishing...there is NO universal standard method. Just about everyone spends years trying different approaches and ends up with their own way of french polishing. These days I use hard shellac and after a couple of seal coats I go through body sessions with intervening cut back sessions using oil and wet and dry. I use walnut...its a non drying oil and it seems to blend nicely with the shellac.


WilliamDavidReynolds wrote:
Fri Jan 27, 2023 2:33 pm
lamanoditrento wrote:
Mon Nov 28, 2022 8:43 am
. I french polish with something more akin to a 1/3 to 1/4-pound cut which would be around 1:16. The important ratio is a 1ml of harder to 1g of shellac.
So I’ve been gearing up for traditional shellac finishing, because it looks amazing and is def more shop friendly.
I’ve been looking at every shellac/French polish badass I can find etc etc,
This thread is a good one, so the Hardener makes the shellac more sustainable? More durable? Or is this a benefit for the shellac itself?
The only reason I’ve been not hastily ordering flakes is the durability aspect.
I learned Ken Parker’s method of epoxy and oil over the epoxy, and was thinking shellac over epoxy might be pretty good, not just epoxy pore filling but a rubbed on rubbed off coat like Ken does and shellac over?
Looks I just rambled out more questions than I started typing with.
Martin

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kiwigeo
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Re: Shines hardened shellac - ratios

Post by kiwigeo » Fri Jan 27, 2023 4:13 pm

Bob_H wrote:
Fri Jan 27, 2023 2:59 pm
WilliamDavidReynolds wrote:
Fri Jan 27, 2023 2:33 pm

... so the Hardener makes the shellac more sustainable? More durable? Or is this a benefit for the shellac itself?
The Shines website claims that when the hardener is added, the final finish is "much harder than an ordinary shellac finish. This coating withstands heat, water and alcohol". It takes a couple of weeks after application for the benefit to be realised.
I give my guitars at least 30 days for the hardener in the hard shellac to fully cross link. Its temperature dependent.
Martin

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