Marcus Bretto

Cooking Varnish in a Melting Pot?

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Hello all! So, I've  been really excited about trying to cook my first batch of oil varnish. I've been researching the forums on here/ various things on the internet and getting supplies for the job. I was planning on purchasing a hotplate for cooking the varnish on when I discovered a "dip coat melting pot" while cleaning out the basement of our shop. It looks like an industrial glue pot with temperature control ranging from 100 to 500 degrees F. Looking them up online shows me that they are designed specifically for heating viscous materials evenly (plastics, resins, ect.) and often come with "thermostatic control to eliminate carbonization". Seems like its the sort of thing that would be perfect for cooking varnish! Has anyone done or heard of others using these things, or just have opinions on the matter? Also, any more varnish tips/ suggestions would be well appreciated. 

-Marcus

Edited by Marcus Bretto

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Don't cook varnish if you aren't certain about what you're doing and your safety precautions.

Fire and explosion are real dangers.   Cooking varnish is only a little different than cooking gasoline.

 

 

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There are two things that might not be too good about that:

1) When you're done cooking, you have to pour the varnish into something else to filter it or otherwise store it.  The melting pots I see are unitized, so you have to lift the whole thing, and they are not made for pouring stuff out.  Could get very messy, and being messy with hot oil is not a good thing.

2)  Cleaning it.

There might also be a concern about what you do if the unexpected happens... something foams and boils over, or catches on fire.  It's much easier to deal with a small pot with a handle on it.

I have used the hotplate/pot as well as a small deep fryer, and I like the former better.

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The 7 holy rules of varnish making:

1. When you follow your beliefs, all is at your own risk, even when following advices of others. 

2. Use whatever you think is right, only experience will tell you what was wrong, for the pot for the procedure and for the ingredients. 

3. Working outdoors can prevent the worst disasters. However be prepared for some verbal attacks from your wife about smoke and unpleasant odors.

4. Just be careful because this can become an obsessive and addictive occupation not properly recognized by psychologists.

5, if you burn down a building, you will be remembered in violin making history.

6. If you explode yourself, you will have a special seat in the hell of violin makers, because you know how to make fire. 

7. If you find THE recipe, something was wrong, but don't tell anyone.

Have fun!

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A few precautions:

If using a hot plate, there might be only a few points  of actual contact between the coils and the container. These can get much hotter than the surrounding areas of the container, along with varnish which is in contact with them, and lead to reactions you didn't expect from the average temperature of the varnish indicated by your thermometer. A sand bath helps distribute the heat more evenly.

Volatile fumes can come from the varnish, and ignite when they make contact with the heating coil.

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Hey Marcus,

I just cooked down some amber last week, and happened to take a photo of the rig, so I can post it here.  I like to use a cheap pot for this because it's very hard to clean things, and eventually I'll just toss it.  It has high sides so if things do start to foam it won't spill over. The pot in this photo is actually sold as a counter-top container for kitchen utensils.  

Besides cooking outdoors, I think it's important to have a respirator - the smoke from this stuff is really noxious and if you breath it in by mistake you'll regret it.

 

IMG_0943.thumb.jpg.976fdbf5f9195ec38d860916a72a2a5a.jpg

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22 hours ago, Marcus Bretto said:

Hello all! So, I've  been really excited about trying to cook my first batch of oil varnish. I've been researching the forums on here/ various things on the internet and getting supplies for the job. I was planning on purchasing a hotplate for cooking the varnish on when I discovered a "dip coat melting pot" while cleaning out the basement of our shop. It looks like an industrial glue pot with temperature control ranging from 100 to 500 degrees F. Looking them up online shows me that they are designed specifically for heating viscous materials evenly (plastics, resins, ect.) and often come with "thermostatic control to eliminate carbonization". Seems like its the sort of thing that would be perfect for cooking varnish! Has anyone done or heard of others using these things, or just have opinions on the matter? Also, any more varnish tips/ suggestions would be well appreciated. 

-Marcus

If you have what I suspect you do, don't use it for anything by just pouring stuff into it.  Fill it with a heat transfer medium (such as sand, fine salt, glass beads, alumina, or whatever), then partially bury a container (such as a beaker or a crucible) filled with what you want to heat/cook/dehydrate, in the heat transfer medium.  Also, never trust rheostat markings or thermostat settings on heaters, use a thermometer.  Several dry runs to calibrate your setup is also a very good idea.  All I'm telling you is a standard lab technique for using an electric heating device without having to clean goo out of it afterwards.  I'm not one of the hardcore varnish cultists around here, just know my way around labs where such stuff is done.  :)

BTW, unless you have access to a genuine lab with real exhaust hoods, containments, and fire protection, only do  adventurous procedures like cooking potentially explosive and lethally toxic materials waaaayyyy  outdoors. 

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18 hours ago, Kevin Kelly said:

Hey Marcus,

I just cooked down some amber last week, and happened to take a photo of the rig, so I can post it here.  I like to use a cheap pot for this because it's very hard to clean things, and eventually I'll just toss it.  It has high sides so if things do start to foam it won't spill over. The pot in this photo is actually sold as a counter-top container for kitchen utensils.  

Besides cooking outdoors, I think it's important to have a respirator - the smoke from this stuff is really noxious and if you breath it in by mistake you'll regret it.

 

IMG_0943.thumb.jpg.976fdbf5f9195ec38d860916a72a2a5a.jpg

Thanks for posting the picture of your setup.  I've got two hot plates neither put out enough heat to cook in a sand bath.  The Corning lab hot plates are affordable if you buy used on ebay.  Quite pricey new.   I don't plan on making amber varnish, but I would like to try it as a ground.  What ratio oil/resin are you using?

Thanks,

Jim

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7 hours ago, Jim Bress said:

Thanks for posting the picture of your setup.  I've got two hot plates neither put out enough heat to cook in a sand bath.  The Corning lab hot plates are affordable if you buy used on ebay.  Quite pricey new.   I don't plan on making amber varnish, but I would like to try it as a ground.  What ratio oil/resin are you using?

Thanks,

Jim

I've been making varnish for several years on a NuWave induction cook top. But this year I bought a lab hot plate and temperature probe from Hogentogler.

https://www.hogentogler.com/thermo-scientific/hp88857104-cimarec-plus-digital-hotplate.asp

 This model comes with an aluminum top.  Pretty good price I think.

I don't think 572F is hot enough to run amber but it's hotter than the NuWave and will work fine for making my varnish.

If I want amber varnish I'll buy from Nunzio or Joe.

 

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3 hours ago, lpr5184 said:

I've been making varnish for several years on a NuWave induction cook top. But this year I bought a lab hot plate and temperature probe from Hogentogler.

https://www.hogentogler.com/thermo-scientific/hp88857104-cimarec-plus-digital-hotplate.asp

 This model comes with an aluminum top.  Pretty good price I think.

I don't think 572F is hot enough to run amber but it's hotter than the NuWave and will work fine for making my varnish.

If I want amber varnish I'll buy from Nunzio or Joe.

 

Thanks for the suggestions.   For the hot plates both of mine will exceed 300 C (572 F) which is the limit of my infrared temperature gun.  For cooking colophony down for color I go to 300 C for a short time.  I prefer to cook in a sand bath for even heating, but I can barely get to 200 C unless I cook directly on my hot plate.  Which is the main reason I want a hot plate that heats to higher temperatures.  

Incorporating amber is still in the thought model stage.  I try to only change one thing at a time.  I've done all my testing for this instrument.  Possibly using Amber in my ground will be for the next if I go that route.  For me that's still a year away.

-Jim

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4 hours ago, Jim Bress said:

Thanks for the suggestions.   For the hot plates both of mine will exceed 300 C (572 F) which is the limit of my infrared temperature gun.  For cooking colophony down for color I go to 300 C for a short time.  I prefer to cook in a sand bath for even heating, but I can barely get to 200 C unless I cook directly on my hot plate.  Which is the main reason I want a hot plate that heats to higher temperatures.  

Incorporating amber is still in the thought model stage.  I try to only change one thing at a time.  I've done all my testing for this instrument.  Possibly using Amber in my ground will be for the next if I go that route.  For me that's still a year away.

-Jim

Sure, What kind/brand of hot plates do you have? If they exceed 300C then I assume they are laboratory hp's?

How much sand are you using? I find a thin layer is appropriate rather than burying the entire vessel.

Nunzio's amber and copal varnishes are an option if you don't want to make your own.  If you do get around to running amber please document it here if possible.

 

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19 minutes ago, lpr5184 said:

Sure, What kind/brand of hot plates do you have? If they exceed 300C then I assume they are laboratory hp's?

How much sand are you using? I find a thin layer is appropriate rather than burying the entire vessel.

Nunzio's amber and copal varnishes are an option if you don't want to make your own.  If you do get around to running amber please document it here if possible.

 

Hey E,  My hot plates are cheap stuff under $30 each.  If I follow through with my current thoughts I will purchase some amber varnish.  What I'm not sure of is the "best" choice for oil/resin ratio.  In all likelihood if my trial is a noticeable optical or sonic (higher probability of results not due to ground) success I will run my own amber because I'm a control freak. :)

I don't know that I'll remember to document, but feel free to ask.  I have no secrets.

-Jim  

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16 minutes ago, Jim Bress said:

Hey E,  My hot plates are cheap stuff under $30 each.  If I follow through with my current thoughts I will purchase some amber varnish.  What I'm not sure of is the "best" choice for oil/resin ratio.  In all likelihood if my trial is a noticeable optical or sonic (higher probability of results not due to ground) success I will run my own amber because I'm a control freak. :)

I don't know that I'll remember to document, but feel free to ask.  I have no secrets.

-Jim  

Sounds intense...have fun!

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On 7/17/2018 at 6:48 AM, Jim Bress said:

Thanks for posting the picture of your setup.  I've got two hot plates neither put out enough heat to cook in a sand bath.  The Corning lab hot plates are affordable if you buy used on ebay.  Quite pricey new.   I don't plan on making amber varnish, but I would like to try it as a ground.  What ratio oil/resin are you using?

Thanks,

Jim

Hi Jim,

I did buy the hotplate used on ebay, and it works great. I try to make 1:1, but I don't have control enough to say that it comes out that way.  I have some with way too much oil, and some with way too much resin, and I mix them together at the varnish bench.   Just making sauce...

My experience melting amber is that it's very hard to get it all to melt, so I have a bunch of rocks left over in the pot.  These get recycled for the next time, but it means you have to figure out how much actually melted before you can try to manage any oil/resin ratio.  The pic above is from me "quickly" melting some amber powder to have available to add to varnish with too much oil. 

I often use Joe Robson's varnish, but I like to keep my hand in as well. 

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