Sign in to follow this  
Andreas Preuss

Hardener for shellack

Recommended Posts

On 8/4/2020 at 1:25 PM, Andreas Preuss said:

This is basically a question addressed to people here with chemical knowledge.

I would like to get shellack quicker hard after application. Are there any additives which can achieve this?

The shellack I am currently using is the dewaxed quality in flakes. 

It dries just by evaporation of the solvent. Use isopropanol and it will dry faster.

The problems with getting hard seem to arise from esterified components of the shellac which you avoid by using a good quality shellac and by dissolving it fresh every time.

http://www.michaeldresdner.com/how-and-why-does-shellac-go-bad/

Share this post


Link to post
Share on other sites
17 hours ago, uguntde said:

It dries just by evaporation of the solvent. Use isopropanol and it will dry faster.

The problems with getting hard seem to arise from esterified components of the shellac which you avoid by using a good quality shellac and by dissolving it fresh every time.

http://www.michaeldresdner.com/how-and-why-does-shellac-go-bad/

Thanks. Seems you know the chemistry. 

Actually we used in Tokyo violin making school Isopropanol. However Mr. Murata didn't say it evaporates faster he said it doesn't attract moisture so much. 

I always thought that the bigger the molecules of the solvent the slower the evaporation process. Seems to be wrong. 

Share this post


Link to post
Share on other sites
13 hours ago, Andreas Preuss said:

Thanks. Seems you know the chemistry. 

Actually we used in Tokyo violin making school Isopropanol. However Mr. Murata didn't say it evaporates faster he said it doesn't attract moisture so much. 

I always thought that the bigger the molecules of the solvent the slower the evaporation process. Seems to be wrong. 

It is correct that moisture in methanol is a problem. You can of course buy 99.9% methanol but this a lot more expensive. Particularly during the pandemic it has become hard to get a hold of pure ethanol. Isopropanol is indeed much better in that respect.

I have made spirit varnishes with iso-propanol and some makers like it better. You need to be quick with the brush if you use isoprop.

Among unbranched molecules longer does indeed mean higher boiling point. But the iso does the trick to lower the bp.

Share this post


Link to post
Share on other sites
On 8/5/2020 at 12:16 AM, Andreas Preuss said:

 

Here in Japan humidity is pretty high all year long 

Hello Mr. Preuss. I think I have a similar problem here in Syracuse, Sicily. I have experimented with using a different solvent for shellac-based retouching varnish. Ethyl lactate seems promising. It is sold in Italy as a xylene substitute in cleaning operations but I found that it acts differently from xylene. For example, it's not practical to treat and remove hardened rosin spots on old varnishes with ethyl lactate. But, when mixing pigments and applying retouching varnish, I think that ethyl lactate works well in humid environments. For me, adding a few drops of ethyl lactate to pigments/varnish looks like using spike oil for brushability but it hardens much faster.

I will try to make an isopropyl alcohol/ethyl lactate mix for a simple retouching varnish (shellac + sandarac). The idea is that ethyl lactate would compensate for a faster evaporation and allow a better brushability. It's a pity that ethyl lactate has such a bad smell compared to spike oil.

 I'll be happy to hear about your results if you decide to do some experments with those solvents.

 

 

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
Sign in to follow this  

  • Recently Browsing   0 members

    No registered users viewing this page.