Lead white II

[Rolf]

I started making lead white according to a recipe I found on the net. "Take a piece of lead, put in a jar with some 30% vinegar. Store it in a warm place for a couple of weeks. This is two weeks product. The jar was kept in the washroom at 30 degrees Celsius. As you can see it works, but its going to take along time to get a teaspoon full.



I found a store that had an old tube of lead white oilpaint. It contains a mixture of lead white and zink white. Can use this to boil linsead oil or will the zink ruin the oil?

Best regards

Rolfkt

[Jim Kibler]

Rolfkt,

Another option if you want to incorporate lead into your oil is use a method Eric Kettenburg mentioned some time ago.  If I rember correctly, he simply put lead shot in the oil and heated the oil and lead above the lead melting point but below the flash point of the oil.  I do recall him mentioning this is a pretty narrow window and keeping this temperature can be a bit tricky.  I'm pretty certain he was happy with the results, so I'm sure it's good method.  If you search the archives you may be able to find mention of this. 

Jim

[Joe S]

If you try Kettenburg’s method, here's a couple of things to keep in mind: the melting point of lead is 327.5 C (621.5 F) and the boiling point of linseed oil is 343 C (631 F).  When linseed oil reaches the boiling point, it doesn't just sit there and bubble like a pot of boiling water.  Instead, you will hear a soft whump, and see a very large fireball ascending in an even larger cloud of inky black smoke.  When you look in your pot, there will be no more oil.  At least that's my experience.  You might invite your friends – it's fun to watch.

[Jim Kibler]

Here is the link to where Eric Kettenburg mentions his method.  http://americanlongrifles.org/forum/index.php?topic=5097.0;wap2

[Ryan McNabb]

I just tried this.  I bought raw linseed oil and heated it to a gentle "quiver" (it wouldn't get to a boil on the electric hotplate I was using) and at this point I slowly dripped in small pieces of real white lead oil paint (not lead and zinc or lead and titanium).  It did foam up agressively as he said it would.  I put into the pint of raw oil, probably about a solid teaspoonfull of lead paint.  I was never able to find a quantity to put in, or any quantities of oil or lead, or if there is a different quantity for dry lead carbonate, so this was guess work. 

The oil did get very dark - almost as dark as coffee - but I cannot tell that it has any propensity to thicken.  I let it set for 3-4 days and it showed no signs of thickening.  I am now letting it sit without a lid on it, and I believe perhaps it is thickening a little.  But the smell is terrible - it doesn't have that wonderful linseed oil smell, it smells like fish.  I can't stand the smell.

I am unconvinced about my technique.  I'm not sure I got the oil to the right temp because I don't know what temp to get it to.  I'm not sure I use lead in a proper form (the oil paint was made with safflower oil, and I don't know if this was an unacceptable adulteration - somehow I doubt it mattered) and I'm not sure that there are 3 or 4 other things that I've done wrong. 

I have several lead ingots in the shop and they get carbonate white lead crust on them all the time.  I could just save this in a bottle and use it - I could just brush on some vinegar and scrape off the white lead, then repeat.  Easy and free.

Also, one supply house has plain dry flaked lead carbonate which I believe would be better than using oil paint, but it's more expensive.

http://naturalpigments.com/detail.asp?PRODUCT_ID=475-11S

I'm also not sure if this oil will be any good for making into Eric's Plain Brown Varnish - I hate to risk all those resins on an oil that won't work. 

[Rolf]

I think I'll wait until I've got a teaspoon of lead white.
I'm not brave enough to try that stunt with molten lead and boiling linsead oil.

Best regards

Rolfkt

[Jim Kibler]

That might be the safest option, but just a word of note.  If Eric Kettenburg believed it was a good workable process I'm sure it is. 

[Joe S]

I have had some discussion with Kettenburg about his process, and he agrees that it has a high entertainment potential, especially because he makes rather large batches.  He does lose one from time to time.

I also have some of his varnish, made by this high temperature process.  As you would expect, it is dark, viscous and fast drying.  You can get exactly the same result by cooking at about 204 C (400 F) for 30-45 minutes, and adding 0.2% lead carbonate (weight to volume).  I don’t see anything special about the varnish Kettenburg makes.  So why does he make it that way rather that at some more controllable temperature?  I don’t know.  Perhaps a spirit of adventure?

Rolfkt – Generally speaking, the rate of chemical reactions double with every 10 degree increase in temperature, so if you warm your vinegar and lead container a little, it will greatly speed up the process.

[Ryan McNabb]

I don't mean to be thick, but could you explain "2% weight to volume"?  If I'm boiling a quart of oil, do I use 2% of the weight of the oil, or the volume of the oil, or something else?

Thanks

[Joe S]

Ryan – You’re not being dense.  Weight to volume is chemistry jargon, and I wasn’t thinking about a general audience when I wrote that.  Weight to volume is the amount of solid (weight) divided by the volume of the liquid, expressed as a percent.  For example, a 1% weight to volume solution would be 1 gram solid dissolved in 100 ml of liquid.

[Joe S]

Ryan

Here’s a formulation for Brown Varnish that will make a nice, fast drying PC varnish.  This recipe is slightly modified from the formula Kettenburg published in Muzzleblasts.

1 pint linseed oil
4 oz gum benzoin
4 oz rosin
1 teaspoon lead carbonate
1/4 – 1 pint of turpentine

Add the lead carbonate to cold linseed oil.  Heat to 400 – 450  (F) for 30 to 45 minute with occasional stirring, then allow to cool.  This is now boiled linseed oil (BLO).  If you don’t have a high temperature thermometer, one period recipe calls for heating the oil until it will scorch a feather.  This works.  Feathers scorch at about 460 F according to my thermometer.

Grind the rosin and gum benzoin with a mortar and pestle, or marble rolling pin.  The resins should be as fine as flour.  

Dissolve rosin in 1/4 – 1 pint of turpentine by vigorous shaking in a glass jar for a couple of minutes.  Add immediately to cold BLO.  

Dissolve gum benzoin in ethyl alcohol and add immediately to cold BLO.  Not all of the gum benzoin will dissolve, but get as much in solution as you can.  Heat the BLO/resin solution slowly with constant stirring to 225-250 (F) for 10- 15 minutes.  There will be some non-soluble black goo from the gum benzoin, but slow heating and constant stirring will minimize goo formation.

Gum benzoin is a real PITA to work with.  It is impossible to get all of it in solution, and if you don’t raise the temperature slowly and stir a lot, you will end up with some big black gum balls.  Kettenburg recommends filtering.  I don’t filter because it is really hard to get the varnish to flow through any kind of filter.  When I’m done cooking it, I just carefully decant it, leaving the solids in the pot.  You lose a little oil, but it’s no big deal.

During the initial heating with the lead carbonate, at about 320 F you will see some fine bubbles forming, but no aggressive foaming.  The bubbles indicate that the lead carbonate is going into solution.  In my experience, after about 10 to 15 minutes the bubbles stop, indicating that the reaction is complete.  So, the process window for oil temperature is about 320 to 630 degrees.  Short heat times and low temperatures result in a thinner, honey colored BLO.  Higher temperatures and longer heat times give you darker, thicker, faster drying BLO.

During the second heating, you will see the oil boil at about 168 degrees.  This is the alcohol boiling off.

Use good linseed oil.  I have had good luck with Varnish Maker’s Linseed Oil from Wood Finishing Enterprises.  Personally, I wouldn’t use the lead you used.  The pure lead carbonate from your link looks like a good product, and is actually made by a PC process.

I’ve also used WW grade rosin from Wood Finishing Enterprises.  Here’s a link to some gum benzoin:  http://woodworker.com/cgi-bin/FULLPRES.exe?PARTNUM=850-679m

[Ryan McNabb]

Thanks Joe - that explains a lot.  I have that gum benzoin.

I looked at the oil I boiled again and it does in fact dry pretty hard.  It imparts no apparent color to plain wood that I can see, even though it's very dark.  But it does seem to dry pretty hard.  I will strain it and use it for a batch of varnish. 

[Rolf]

I figured out an easy way to speed up the chemical reaction. Just add sparkling water to the vinegar in the jar!!!!
Vingar vapors react with the lead and make lead acetate. The lead acetate reacts with carbondioxside in the air to make lead carbonate(lead white). Sparkling water increases the CO2 in jar. I can now actually see the lead white growing on the metal.

Best regards

Rolfkt