Rimino

Varnish Temperature

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Hello everyone,

I really appreciate the help you gave me recently.  I am checking the temperature with thermometers, cooking with a metal 1/3 c measuring cup with a little over 1cm deep of varniish.  I tried a dial meat probe thermometer, a craftsman infrared thermometer and a Bluetooth meat thermometer.  The dial thermometer at 200 deg celcius caused the varnish to rapidly flow with an abundance of steam and I couldn’t stand within 20 feet of the pot for very long due to the steam.  I cooked out in a wide open space outdoors.  At 200 deg celcius with both the infrared thermometer and the Bluetooth meat probe the varnish emitted a very weak and light steam flow.  After cooking a while with the dial meat probe the varnish gave a fine bunch of strings with the string test in less than or about an hour.  When cooked while measuring with the infrared and Bluetooth thermometers at 200 deg celcius the varnish only produced one string, not passing the usual string test for a fine bunch of strings, so I had to raise the temp to 288 deg celcius for a half hour and the steam flowed same as when using the dial probe at 200deg c and the varnish began to produce a fine bunch of strings.  I used Roger Hargrave’s recipe (without mastic) and directions in his double base making book and used 1:1 rosin to oil.  Is the varnish supposed to steam so much that you have to stand 20 feet away or is this excessive heating?  If the varnish gives off only light/weak steam/smoke this(?) doesn’t seem to be enough heat to make varnish.  I don’t know if I should trust the dial meat probe or the infrared and Bluetooth thermometers (both of which gave equal readings).  Is 200 deg celcius heat cooking varnish for two hours realistic?   Thanks everyone.

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I've found that heating the oil too much causes drying issues and can affect the color.  288 is probably too hot for combining. 
Why did you decide to forgo the mastic?

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15 minutes ago, DoorMouse said:

I've found that heating the oil too much causes drying issues and can affect the color.  288 is probably too hot. 
Why did you decide to forgo the mastic?

I thought just rosin and oil was necessary.  I thought that if the varnish only pulled one string that it wasn’t heated enough (or possibly not heated long enough).  Does adding mastic make it pass the string test making a fine bunch of strings?

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Not one to try reinventing the wheel, I trust someone that has spent his working life learning to make a good varnish.  My notes on Roger's varnish from the Making a bass blog:

• 500 grams colophony (resin)

• 50 grams mastic tears

• 450 grams cold pressed linseed oil

• Heat the linseed oil to 200C

• Slowly add the colophony (resin) and stirred for at least 2 hours

• Allow the oil/resin mix to cool to 100C. Add the powdered mastic tears last of all and stir for 1 hour more.

• It is extremely important NOT to remove the cooking pot from the stove and place it on a cold surface. This can cause a violent reaction.

• The still warm, but NOT HOT varnish can then be filtered.

This is just the varnish.  If you're cooking down colophony for color (separate from the above procedures) you may want higher temperatures.

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7 minutes ago, Jim Bress said:

Not one to try reinventing the wheel, I trust someone that has spent his working life learning to make a good varnish.  My notes on Roger's varnish from the Making a bass blog:

• 500 grams colophony (resin)

• 50 grams mastic tears

• 450 grams cold pressed linseed oil

• Heat the linseed oil to 200C

• Slowly add the colophony (resin) and stirred for at least 2 hours

• Allow the oil/resin mix to cool to 100C. Add the powdered mastic tears last of all and stir for 1 hour more.

• It is extremely important NOT to remove the cooking pot from the stove and place it on a cold surface. This can cause a violent reaction.

• The still warm, but NOT HOT varnish can then be filtered.

This is just the varnish.  If you're cooking down colophony for color (separate from the above procedures) you may want higher temperatures.

Just without the mastic, I did all of this.  It pulled just one string, not a bunch of fine strings like many people here told me was necessary.

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Why did you not want to use mastic?  I don't know how the varnish would be different without it because I always use it.  Have you made a sample and tested how it dries with UV?

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It is difficult to control temperature accurately in small batches.  In a larger batch it is possible to view the temperature at the top, bottom and sides of the cook and use this to determine the outcome.

on we go,

Joe

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36 minutes ago, Jim Bress said:

Why did you not want to use mastic?  I don't know how the varnish would be different without it because I always use it.  Have you made a sample and tested how it dries with UV?

I’m just plain simple; it dries perfectly but bubbles form immediately while applying (which aren’t present in the jar) by hand or brush which make the coat rough looking when dry.    I cooked it hotter at 288 deg c for a half hour after cooking it according to the Hargrave’s directions and only after 20 or so minutes after application tiny specks/globs of oil formed throughout the coat.

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24 minutes ago, Rimino said:

   I cooked it hotter at 288 deg c for a half hour after cooking it according to the Hargrave’s directions and only after 20 or so minutes after application tiny specks/globs of oil formed throughout the coat.

Uh oh,  sounds like worms. Did you wash the oil?

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3 minutes ago, lpr5184 said:

Uh oh,  sounds like worms. Did you wash the oil?

I washed it twice by 1:3 oil to water shaking for 1 minute per day for a week, let set for a week and then extracted it with a medicine dropper.  It was perfectly clear before washing and cloudy after.

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Did you clear the oil before cooking?

The cloudiness is water still trapped in the oil. To clear you can heat the oil VERY VERY slowy just below the boiling point of water 212F until clear. If you heat too fast and too hot the oil will violently erupt shooting oil every where. Ask me how I know...

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I used to have a problem with "worms" developing in the varnish coat immediately after applying and during drying of the varnish. There are others too who have had problems with this. Look in the MN archives to find old threads.

I finally cured the problem by washing an organic cold pressed linseed oil ( ALLBack) using the Water, Salt and Sand method explained in the .pdf above. Also I now cook above 500F where before I was ccoking around 400F.

With these two changes I no longer get any worms and the varnish dries quickly without the need for any driers.

The Water, Salt and sand method is laborious but to me is worth the cost and effort. Roger and many others only do a quick wash and still make good varnish. This method has worked well for me and I'll continue to do it as long as I make varnish. Give it a try and see for yourself. 

 

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15 minutes ago, lpr5184 said:

I used to have a problem with "worms" developing in the varnish coat immediately after applying and during drying of the varnish. There are others too who have had problems with this. Look in the MN archives to find old threads.

I finally cured the problem by washing an organic cold pressed linseed oil ( ALLBack) using the Water, Salt and Sand method explained in the .pdf above. Also I now cook above 500F where before I was ccoking around 400F.

With these two changes I no longer get any worms and the varnish dries quickly without the need for any driers.

The Water, Salt and sand method is laborious but to me is worth the cost and effort. Roger and many others only do a quick wash and still make good varnish. This method has worked well for me and I'll continue to do it as long as I make varnish. Give it a try and see for yourself. 

 

Great, thanks a lot for the time and work.  You’ve acquired time for me.  I’ll be at this to see it through.  

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3 hours ago, Jim Bress said:

  My notes on Roger's varnish from the Making a bass blog

May I please know if you know how Roger clears his varnish?

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He describes a simple method in the bass blog that will likely not have a better result than the Tad Spurgeon salt and sand method.  That said, I don't think he washes the oil at all and just buys high quality cold pressed linseed oil.  Of course I am not Roger.  If Roger comes on, what ever he says he does is the correct answer.  I clear my washed oil (similar to how you washed) with a centrifuge.

before

622893108_Linseedoilbeforecentrifuge.thumb.JPG.5e7a167b6d04ac66be9e76ffc431f21d.JPG

After

388049288_Linseedoilaftercentrifuge.thumb.JPG.7d35d70aef73941d543d2b14ce16b86e.JPG

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27 minutes ago, Jim Bress said:

He describes a simple method in the bass blog

Thanks for explaining your method.  I checked Roger’s book for how to clear varnish but only found how to wash the varnish.

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7 minutes ago, Rimino said:

Thanks for explaining your method.  I checked Roger’s book for how to clear varnish but only found how to wash the varnish.

I expect it will clear in the cook.  If I didn't have a centrifuge I would probably cook the oil just enough to boil off the water.  Again, there are lots of folks (professional makers) that don't wash their oil at all.  Some of the unwashed masses will speak up if they are so inclined.

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6 hours ago, lpr5184 said:

To clear you can heat the oil VERY VERY slowy just below the boiling point of water 212F until clear.

I didn’t see this before I asked how.     Does this alone clear it sufficiently so that bubbles don’t get trapped on applying or (worms) tiny specks/globs don’t develop or so that nothing else goes wrong?

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3 hours ago, Jim Bress said:

Again, there are lots of folks (professional makers) that don't wash their oil at all.  Some of the unwashed masses will speak up if they are so inclined.

I wash.

on we go,

Joe

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6 hours ago, Rimino said:

I didn’t see this before I asked how.     Does this alone clear it sufficiently so that bubbles don’t get trapped on applying or (worms) tiny specks/globs don’t develop or so that nothing else goes wrong?

Yes heating the oil very slowly as explained will completely clear the oil. While heating you will see the water bubbles trapped on the bottom of the pan slowly rising to the top of the oil...BUT if you heat above 212F and too fast the water will explode and hot oil will shoot up out of the pan. This should be done outdoors in case this happens. I have washed and cleared  gallons of oil this way. Once you do it you will understand and have control of the process.

As far as your specks and bubbles in the varnish, I really don't know if what you are describing are worms or not. I haven't followed your previous posts so I don't know what kind of oil and resin(s) you are using. If it is worms,...they will seem to grow after application and appear as little squishy droplets. You can try washing the oil well and cook above 500F to a firm pill to see if that solves the problem.

It did for me,... but I use the same type of oil and resin now, where before I was experimenting with many different brands and types of oil and resins. Once you find material that work buy in quantity and stick to that.

This is the best I can tell you from my past experience with making varnish. I have spent way too much time and money but it was worth it I guess. I still make varnish but also buy commercial varnishes from experienced varnish makers. It saves a lot of time and money.

Best of luck and think safety first,... eyewear and long sleeves at a minimum.

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