Chocolate Varnish

[Joe S]

I made a batch of varnish this afternoon, using Bill Knight’s recommendations for boiling the oil.  His recipe calls for 2% (weight to volume) lead carbonate, and boiling the oil at 550 degrees for two hours.   I followed his instructions exactly, and the BLO came out the color and consistency of chocolate syrup.  It is going to take a lot of turpentine to thin this stuff down to where it’s usable.

Other batches I’ve made at somewhat lower temperatures and with substantially less lead have come out a deep ruby red.

I used Grumbacher linseed oil, which I have had good results with in the past.   The oil was boiled in a small galvanized bucket.  I’m wondering if the zinc from the bucket might have reacted with the oil/lead.

Any thoughts? 

I also made a batch of shellac today.  It looks fine, however the instructions I have specify that I should use a skunk hair brush for applying the shellac to my stock.  I don’t have one so I’m going skunk hunting tonight.  Anyone want to go along?

[bob in the woods]

I'm pretty certain that the zinc is responsible for your chocolate ,thick syrup.
I like old enamalled, or ss pots.

[Ben I. Voss]

Joe, we have plenty of extra skunks around our homestead - please feel free to help yourself!

[David Rase]

Joe,  Hurry up and get that recipe right.  I plan on coming up to Montana to your gunmakers fair and I see from the flier that Bill sent me that you will be teaching a class in Varnish making.  Looking forward to meeting you in person.
DMR

[Eric Kettenburg]

I've stopped using lead carbonate as it makes for a lot of extra filtering afterwards to get it all out and I can tell you I've never used more than about a tablespoon in a coffee-can's worth of oil.  I don't know how that relates to the 2% ratio by volume but that sounds like a lot - more $#@* to filter.  Also - 2 hours at that temperature is going to yield a big blob of linoleum, or a 'soccer ball' as I like to call it.  With the method I use now, which involves boiling the oil in the presence of molten pure lead, I bring it very slowly to a true rolling boil, keep the oxygen out with a cover (keeps it from frothing over for a short period of time) and give it maybe 5 minutes at that temp.  Any more than that and you will thicken it unecessarily and basically burn it.  This always gives me the somewhat thick, very red-gold-amber color to the oil. 

[Sean]

...involves boiling the oil in the presence of molten pure lead...

Eric, could you please explain what you mean here?

Thank you,

Sean

[Mad Monk]

I've stopped using lead carbonate as it makes for a lot of extra filtering afterwards to get it all out and I can tell you I've never used more than about a tablespoon in a coffee-can's worth of oil.  I don't know how that relates to the 2% ratio by volume but that sounds like a lot - more $#@* to filter.  Also - 2 hours at that temperature is going to yield a big blob of linoleum, or a 'soccer ball' as I like to call it.  With the method I use now, which involves boiling the oil in the presence of molten pure lead, I bring it very slowly to a true rolling boil, keep the oxygen out with a cover (keeps it from frothing over for a short period of time) and give it maybe 5 minutes at that temp.  Any more than that and you will thicken it unecessarily and basically burn it.  This always gives me the somewhat thick, very red-gold-amber color to the oil. 

The 2% of lead carbonate is based on the fact that the carbonate form is not "rich" in lead metal.  That would give an oil with about 0.5% lead in the oil.

The temperature and time came out of the tech books on the boiled oil industry of old.  An important point is how one heats the oil.  Direct flame against the bottom of the oil cooking pot is to be avoided.  This will burn the oil even if you gently stir the oil while cooking it.  I would cook it over a charcoal fire.

The oil, in this case, started to attack the zinc coating and got to the iron over which the zinc had been applied.  While the iron does not act as a dryer metal it will discolor the oil this brown color.

Any iron in the oil kills the heat stability of the oil while discoloring it.  Small amounts of iron will do ugly things to the oil.

E. Ogre

[Tom Currie]

I don't know much about oil yet, but I don't recommend skunk hunting. Been there , done that. My Uncle , God bless him, had horses and was always worried about rabies so he shot all varmints with his 410. Including skunks.

[Joe S]

Thanks for your responses gents.  I haven’t tried heating oil over charcoal, but I’ll give it a shot.  I heated my first batch over an open flame.  That ended with a soft whump, and a fifteen foot ball of flame.  Currently I’m using a sand bath and an electric hot plate. 

My best varnish results to date have been with Kettenburg’s Brown Varnish.  It can take a couple of days to dry though, so that’s why I was experimenting with higher lead levels. 

I have made a small but useful modification to Eric’s recipe:  I dissolve the resins in alcohol then add them to cold BLO.  I then heat it to 200 degrees, which is about the meting point of the resins.  I do this because I’m not sure if there is some necessary chemistry going on when the resins are melted into the oil.  Heating also drives off the alcohol.  Bill Knight speculated about the possibility of doing this in his book, but apparently had not tried it by the time the book was written.  It works well, plus it gives you the opportunity to filter a lot of the dirt and sticks out of the resin before you put it in the oil.

Dave – I’ve made several batches of varnish, which is several more than anybody else around here, so I am by default the local “expert”.   It would sure be nice if a real expert materialized here – I have a lot to learn yet.  Looking forward to meeting you in August.

Eric – Could you elaborate on your current heating method?  It sounds interesting. 

[omark]

tom, skunk huntin aint bad, its the skinnin. also best to be upwind whenever ya can.         mark         

[billd]

I was going to try it in a deep fryer but ended up buying some from Eric.  My wife probably would have killed me anyway even though she never uses the fryer.

Bill

[Mad Monk]

I would point out here that I did the oil work just about 25 years ago.  At a time when what was being published in the gun mags was utter nonsense.  When Dr. Bill asked me if he could publish my work I agreed.  He used a copy that dates back to around 1984.  I had made up 20 copies to be handed out at one of the Gunmaker's Fair and then simply left the project go to work on powders.

So the work is far from perfect and could use a good re-writing.  But at the time I did the copies for the Gunmaker's Fair it beat by a mile what was then being published.

All of my documentation that I collected was simply handed over to Eric K. with the idea he would simply add it to what he had been doing.

E. Ogre

[Dphariss]

Thanks for your responses gents.  I haven’t tried heating oil over charcoal, but I’ll give it a shot.  I heated my first batch over an open flame.  That ended with a soft whump, and a fifteen foot ball of flame.  Currently I’m using a sand bath and an electric hot plate. 

My best varnish results to date have been with Kettenburg’s Brown Varnish.  It can take a couple of days to dry though, so that’s why I was experimenting with higher lead levels. 

I have made a small but useful modification to Eric’s recipe:  I dissolve the resins in alcohol then add them to cold BLO.  I then heat it to 200 degrees, which is about the meting point of the resins.  I do this because I’m not sure if there is some necessary chemistry going on when the resins are melted into the oil.  Heating also drives off the alcohol.  Bill Knight speculated about the possibility of doing this in his book, but apparently had not tried it by the time the book was written.  It works well, plus it gives you the opportunity to filter a lot of the dirt and sticks out of the resin before you put it in the oil.

Dave – I’ve made several batches of varnish, which is several more than anybody else around here, so I am by default the local “expert”.   It would sure be nice if a real expert materialized here – I have a lot to learn yet.  Looking forward to meeting you in August.

Eric – Could you elaborate on your current heating method?  It sounds interesting. 

If it were me I would go to Sacks Thrift Avenue a few times looking for old deep fat fryers.
I would use this to cook the oil. I would cook it with something to reduce the acidity, like limestone. Cook it for about an hour on maximum for hardware store boiled oil. The let it cool then decant into quart jars and seal them up. I also add a little Japan drier to a gallon of oil. About a tsp full or a little more. Habit I got into never tried any with out this. Use this as a base oil. If the store bought oil is not too dark you should end up with a nice reddish amber oil. This can then be used to make small batches of varnish as you want. It will be a nice oil somewhat fuller bodied than the original oil and will dry pretty rapidly in the sun as is. I like Parks brand but have used other amber oils. Used some stuff that was pretty dark last batch and don't like it, may dump it and make another batch.
I have no idea what the acid level is of the Grumbachers oil but if the organic acids are not reduced it will retard drying.
It is also a transparent oil and its  unlikely that it is similar to what was used by the oil time riflesmiths/varnish makers though by the 1870s or so Ballard, at least, was using a pretty pale soft oil varnish.
My idea for varnish is what was used on Vincent Ohio rifles. The brown varnish on the "Bridger" Hawken in interesting as well if the barrels I have on order ever arrive.

If any of this is wrong Mad Monk can feel free to chastise me. He started me down this road and I am VERY grateful. What I tried of his instructions for making boiled oil worked as he said.
I have not gotten into making varnish aside from mixing the cooked oil with some other Grumbachers products.

Dan

[hyltoto]

I was looking through a really old magazine the other day, WW2 era, and it suggested using a feather to remove bubbles from your fresh coat of varnish.

[Joe S]

Bill – Your book has a lot of useful and interesting information that is not available elsewhere.  I enjoyed reading it, and learned a lot.  Maybe when Eric finishes his book on book on Lehighs, he’ll write us one on varnishes too.  You should coauthor the varnish book, update it, and add in the chemistry.  There are a lot of us out here who would appreciate the technical details.

Regarding Eric’s previous post, I just looked up the physical properties of lead and linseed oil.  Lead melts at 621 degrees (F); the boiling point of linseed oil is 649 degrees.  649 degrees is also the autoignition temperature of linseed oil. Autoignition temperature is defined as “the lowest temperature at which a substance will spontaneously ignite in a normal atmosphere without an external source of ignition, such as a flame or spark”.   I’d say that this process has a narrow operating window, and the potential for a high level of entertainment.   I think I’ll give it a try.

[Leatherbelly]

Quote;
Regarding Eric’s previous post, I just looked up the physical properties of lead and linseed oil.  Lead melts at 621 degrees (F); the boiling point of linseed oil is 649 degrees.  649 degrees is also the autoignition temperature of linseed oil. Autoignition temperature is defined as “the lowest temperature at which a substance will spontaneously ignite in a normal atmosphere without an external source of ignition, such as a flame or spark”.   I’d say that this process has a narrow operating window, and the potential for a high level of entertainment.   I think I’ll give it a try.

 ...a very narrow window indeed!...and the entertainment level should be right up there too, regarding the autoignition and the heat source.
I've been following this post with interest. Question, are you just fuming the oil with the lead or is it in the boiler?
 I can just see it now,a twenty foot fireball landing in my neighbours garden! Like napalm!...sorry,got carried away.

[Eric Kettenburg]

Leatherbelly you've got it - aside from the very stupid and dangerous method by which I boil oil, I am also operating in a very narrow window of temp.  I am melting the lead in the bottom of the coffee can of oil so that the molten lead is in contact with the oil.  It off-gasses enough as it approaches temperature that if a cover is kept on it, it retards foaming by cutting the oxygen to the surface of the oil.  Also the oil CAN NOT be stirred in this process or it will foam up and ignite.  Once it begins rolling under the cover (I keep quickly peeking) I only let it go about 5 minutes.  Any more and it will foam over and ignite ESPECIALLY IF EXPOSED TO OXYGEN.  Also, any more and it will literally cook solid in that time (anyone remember by linoleum soccer ball at Dixon's a few years ago?).  The foaming in the second picture is as a result of about 3 seconds of lid removal and photo taking but at that point it's about ready to remove from heat anyway.  As I see it, by keeping it covered, the fumes given off fill the airspace in the top of the can (which is only filled about 5/8 full to allow room for expansion) and while they will work their way out through a small crack, they displace any oxygen and prevent oxygen from reaching the surface of the oil.  If the oxygen can't reach it, it holds off the foaming and also seems to hold off the spontaneous ignition (yes there have been incidents).  BTW, I use a big sheet metal shield b/t the propane tank and the oil but I had to remove it for the photo.  I don;t remember how I came up with the method of boiling but it yields what I feel to be the best drying oil.  Some of the info Bill gave me years ago was from late 19th century books which all described boiling the oil in an oxygen-deprived atmosphere.  Maybe someone with a chemical background like Bill can explain how the molten lead may be (must be as I see it) effecting such rapid thickening (while boiling) and rapid drying (while in use).  Short of adding manganese or cobalt (you can add a little japan drier for this if you want), high humidity is still an issue, but get this stuff out on a dry sunny day and it dries FAST.

[Eric Kettenburg]

BTW yes there is usually - to some degree or another - a very high entertainment level indeed!

[bigsky]

Joe,
You mention that the boiling point of linseed oil is 649 degrees.  I assume this is at sea level and that actual boiling temperature will be somewhat lower at your elevation.
Kevin

[Acer Saccharum]

entertainment? Like EK shows at Dixon's with no hair?

 

I think I will buy my oil, and forgo the entertainment.

Acer

[Stophel]

That's hotter and a little more dangerous than I want to get...

Here's what I have been doing lately:

For every pint of cold pressed oil, I add one tsp of lead carbonate (and also one tsp of burnt umber).  This isn't very much, and filtering is not a problem.  The way I apply the stuff makes it not much of a concern anyway.

For just linseed oil, I put this in my fryer thing and boil for about an hour.  This is a very low roll, not a frothy boil.  I can't get it that hot anyway...without catching it on fire.  This makes a pretty thick concoction.  For an oil finish, this is OK.  It has some body to it, and it fills the grain much more quickly than a thin oil.  It still needs to be applied LIGHTLY with each application.  It will dry pretty quickly (within a day of sun, but I leave it out longer just to be sure).

For varnish, I just can't have it this thick.  Thin it with turpentine all you want, and you will still have a sticky, tacky mess that will not level and is extremely difficult to get a smooth finish with.  If I boil the oil for only about a half hour, and add the resins, I get a smooth varnish that I can spread out with my fingers.  Not really much thicker than the oil I started out with.  It levels out nicely and seems to do well so far.  It does take longer to dry completely.  A day in the sun gets each THIN coat pretty well dry, but several days to make it stop "fingerprinting" completely.  I have some out in the sun right now drying on some pistol grips.  I put this coat on yesterday morning.  It was pretty much dry by the evening.  Might be totally dry this afternoon.

[billd]

"drying in the sun"......
Does this mean it has to have direct sunlight to dry?
Can I use it on a cloudy day or put it near a window? 
Will it dry indoors but just take longer?

Thanks,
Bill

[Joe S]

There are two separate reactions going on Bill, polymerization and drying.  The polymerization of linseed oil is greatly enhanced by exposure to UV.  To get UV, you need direct exposure to sunlight, as glass does not transmit UV (that’s why you can’t get a suntan indoors).   UV can get through clouds; the thicker the clouds the less that gets through.  Someone did an experiment using black lights to try and speed polymerization of linseed oil indoors.  As I recall, they were not successful.  You could probably find that thread in the old archives.

Turpentine, if you have any in your varnish, actually dries, in the sense that there is a volatile component that leaves the surface.  I would guess that the drying rate of turpentine is primarily mediated by temperature.

High humidity reputedly slows polymerization, but since I live in the West, I have no direct experience with humidity.

To answer your question, linseed oil varnishes will dry indoors, albeit more slowly that if they have some sunshine.  I just put a coat of varnish on a gunstock, so of course it’s snowing.   If y’all have any extra global warming where you’re at, I wouldn’t mind if you sent a little my way, at least until I get this stock finished.  Then it can go back to snowing for all I care.

[Dphariss]

"drying in the sun"......
Does this mean it has to have direct sunlight to dry?
Can I use it on a cloudy day or put it near a window? 
Will it dry indoors but just take longer?

Thanks,
Bill

It always takes longer inside. I have thought of trying a full spectrum bulb for drying finish. But oil will cure pretty fast even indoors if made right.
Lead in the oil speeds drying in high humidity but I seldom have high humidity here.
Its best in direct sunlight I can do 2 fill coats per day in summer. Thats on walnut.

Dan

[Chuck Burrows]

I've found that air flow helps a lot - had a hawk handle this winter: little sun, humidity high for me in SW Colorado at 45%  - hung it in front of a fan in my shop at 68° F and it dried in less than 4 hours....

FYI: My mix was pre-polymerized T & T Varnish with added rosin (locally gathered pinyon rosin) and a bit of lead carbonate - I used a dozen or so .45 caliber lead balls "soaked" in a vinegar atmosphere to promote the "growth - then just dumped them in once it heated up.
I used the T & T since: I had it on hand, it's very good, clean oil, and at 6,500' ASL - getting any oil up to boiling heat is difficult  - I boiled for about a half hour and got a beautiful syrup consistency reddish oil.