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lead based paints

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Kim Ross
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Joined: Wed Jun 27, 2007 1:10 am

lead based paints

Post by Kim Ross »

I've always heard that the old "lead based" paint flowed and covered better than the One Shot of today. I know that white lead (lead carbonate) was ground in linseed oil to form a paste, then added to pigment ..which was mulled in linseed oil. To this, was added various amounts of terpentine and japan driers and sometimes varnishes. I'm assuming that white lead was always used for TINTING a color.. but what about raw pigment colours like red,maroon,greens,blues,yellow, etc. In refering to old colour charts, NO white lead is required in making these colours. So how is lead introduced into these colors? I quess my question would be, were the lead based colours of old, all TINTED colours or were ALL the colours lead based?
Kent Smith
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Re: lead based paints

Post by Kent Smith »

Lead carbonate was not the primary pigment in most formulas, for instance the primary white pigments were formulae if zink and titanium. Note that some of the other lead issues were red oxide(red lead pigments in vaious color intensities), chromium lead oxide (yellow and green), cobalt lead compounds (blues) and others. These pigments are heavy leads and are not soluable in water or blood unlike white lead which is soluable in blood, hense lead poisoning. Heavy leads are only poisonous as inhailants, settling in air sacks in the lungs.

The role of lead carbonate was as an effective dryer. Early Japan dryers were formulated with white lead (sweet lead). Most enamels are a formula of oils, resins (natural or synthetic), solvents and pigments which require a dryer to assist oxygen in the drying and curing process. Alkyd enamels (lettering and bulletin enamels) use a synthesized alkyd oil resin which is very elastic and durable but which will never dry up enough to form a protective film without a dryer. The amount of pigment in each color effects how much dryer is needed in the formulae but as an example, black is the lightest and easiest to dry. Lead dryer is a 3% solution which is essentially a pure solvent (distilled mineral spirits, not oleum) with 3% by weight of lead carbonate dissolved into it. Lettering enamel black had about 10% by volume of this lead dryer in it's formula. Japan dryer typically had 1.5 to 2% lead plus 15 to 20% resin which allowed it to dissolve into paints already formulated and the resin helped to keep the lead in suspension. Too much lead in the paint will coat the resin, keeping oxygen out and keeping it from drying properly. That is why you have to not add too much dryer. Whites have the heaviest pigment loads so that is why they have the most concentration of lead dryer, upwards to 20% which is why many have assumed it was part of the pigment. Even so remember that 20% is of 3% lead solution. Cobalt dryers are a synthetic replacement for lead and are even more senstive to having the correct amount. They are slightly oily and can extend the dry times considerably if too much is added.

By the way, Japan resins, were not synthetic, but natural resin formulated from tree saps, root saps and others. Each type of Japan varnish was made from a different sap or tar. Each resin has its own campatabilty with the surfaces to which it is applied. The dry films also vary as to their resistance to abraision, solvents and UV. Some Japans have been synthesized, such as quick rubbing varnish, to control the formulae variables, but that effects adhesion to such surfaces as glass. Spar varnish as well was made from pine tar. Each of these saps and tars will reduce differently and the amount of dryer varies by that same differential.

As to coverage, higher pigment fomulae could be used with lead dryer. Cobalt dryers cannot be used with too havey a pigment load. Also, the synthetic non-lead pigments themselves tend to be more transparent and do not cover as well.
Kim Ross
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Joined: Wed Jun 27, 2007 1:10 am

Re: lead based paints

Post by Kim Ross »

Thanks, Kent !
I guess I had no idea of the complexity of all this. I was reading a formula for chocolate brown paint - from the late 1930's. It basically went like this: One hundred pounds white lead, 25 pounds of burnt umber, 10 pounds of burnt sienna, 4 pounds chrome yellow, 5 1/2 gallons of linseed oil, 1/2 gallon turpentine, 1 pint of Japan drier. This, apparently will wind up making about 10 gallons of really nifty paint. It goes on to say that some pigments require a great deal more oil than others when grinding to paste form....for example, 25 pounds of white lead will only absorb about 3 pounds of oil in grinding, while 25 pounds of burnt sienna would require almost 45 pounds of oil.
Has alkyd enamels always been used in sign paint or was there a time when paint formuals like the above were adjusted for the sign painter?
Kent Smith
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Re: lead based paints

Post by Kent Smith »

First of all, your formula has some ingredients missing and I suspect when you add resins and solvents that it is for a standard 100 gallon batch and some of the amounts may not be accurate. Using the formula, the color would be much lighter than chocolate but remember that 100 pounds of white lead would not be the same volume as 25 pounds of umber which would just about fill a 25 gallon drum. Some formulae used large amounts of lead carbonate more for the assumed "toughness" of the lead. This is why we have so many issues with lead poisoning and legislation that limits our use of lead pigmented paints.

Alkyd is the cuurent favorite resin for ready-mixed sign paints because it is easily synthesized and formulated. You can pretty much put all the ingrediants in a vat and stir it up. When my Dad first got into the business in the 1920's, they were making their own enamels using spar varnish and blends of Japan varnishes, pigments, dryers and extension with linseed oil and solvent. Somewhere, I still have his formulae for most of the colors he used as he was still making some colors when he began to teach me. He never trusted those ready-made paints for the really important jobs that needed to last the longest. Bulletin enamels were orginally above-waterline marine paints and lettering were reformulated bulletin.
Kim Ross
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Joined: Wed Jun 27, 2007 1:10 am

Re: lead based paints

Post by Kim Ross »

Thanks again, Kent
If you ever run across your fathers' formulas for mixing paint, would you consider sharing? For some strange reason, I've got this real itch to make up my own paint with lead...just to check it out...how it feels in the brush and how it covers - as opposed to the one shot I've been using for the past 25 yrs. ( It seems like the bright red and the black have really gone through some strange changes...for the worse ). Also, I feel that I kinda owe it to myself to explore this for the sake of the craft...please let me know if that is something you would be interested in sharing. Thanks again for all the great information. Kim
erik winkler
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Re: lead based paints

Post by erik winkler »

Kent,

When will the Mastering-paint exams begin this summer?
I know I did not studied enough last year, but I would really like to redo them this year.
Are the books the same as the ones from last years finals?
:D
Realizing we are in the 2nd renaissance of the arts.
Learn, copy and trying to improve...
Still in the learning phase ;-)
Amsterdam Netherlands
www.ferrywinkler.nl
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Kent Smith
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Re: lead based paints

Post by Kent Smith »

Funny Erik,

The exams happen everytime you mix up some paint and apply it. Sometimes you pass and sometimes you fail.

I know I get technical sometimes but there is so much misinformation out there, I hope to be as accurate as possible.

I think Sarah has one of the only good texts out there from Pittsburgh Paint and Glass. There are few good references on the topic since most companies are very secretive about formulations etc.

I have not actually taught a class on paint for many years but would be willing sometime.
erik winkler
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Re: lead based paints

Post by erik winkler »

Kent,

Don't stop!!!
I love it, sometimes real hard to translate in understandable Dutch, but I think it is great.
And failures......... I already had too much.
So please keep up the study material coming!
Realizing we are in the 2nd renaissance of the arts.
Learn, copy and trying to improve...
Still in the learning phase ;-)
Amsterdam Netherlands
www.ferrywinkler.nl
www.schitterend.eu
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Mike Jackson
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Re: lead based paints

Post by Mike Jackson »

There are lots of old books on this topic.

The one I have in my hand is called:
The Mixing of Colors and Paints
by F.N. Vanderwalker
1950
Frederick J. Drake & Co. : Publishers

You can probably find a copy by searching around the Internet.

M. Jackson
Mike Jackson / co-administrator
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Doug Bernhardt
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Re: lead based paints

Post by Doug Bernhardt »

........and I had been waiting to see some responses to this. A good question although I'm not sure running out and buying 50lbs. of white lead is a great idea. Smitty was working in his shop a few years ago and scraping the floor which had been done in lead paints. I think he was on his back after that for about 2 weeks......he'll jump in and be more clear.
Kent Smith
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Re: lead based paints

Post by Kent Smith »

Mike, I agree there are many good texts about mixing paints and mixing colors. What is lacking is good current reference material concerning the formulae of the paints and varnishes on the market. One of my big concerns is the lack of compatability for intermixing of various paints and varnishes. I read and hear many comments from sign painters about their own "secrets" for making paints better etc by intermixing which are so outragiously wrong in formulation it is surprising that they have any success. So often some additive to lettering enamels for instance is widely touted without a real understanding about what that additive is really doing to the curing and durability.

Having said that, when I was working with AKZO coatings, we were able to take one of those ideas and turn it into a new product. Many stripers were using two component urethane additive in their lettering enamels so we had the lab investigate. What they found was that with two minor formula alterations, they could produce a hardener for lettering enamels that was actually compatable and worked. The emphsis should be on the need to alter the formula to make it compatable.

We all could benefit from more formula information particularly that which is current. Most of the current paint formulae were created sometime after 1995 so much of the older texts don't take into account the changes made to meet VOC and lead-free regulations.

Erik, hang in there with translating and let me know if you would like more explaination to help understand some concept.
erik winkler
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Re: lead based paints

Post by erik winkler »

I allmost have every book mentioned in the different bookslists mentioned here on the site.
Read allmost everyone of them. It is in English, it is old, sometimes very old. I love the Drake publishings.
But still it is hard to translate and to edit them in modern ingredients like Kent said.

1) It may sound strange but I still can not put my finger on the commonly used word 'Japan'....
What is it? It is used for allmost everything, but the word Japan in Nederland is used for the black laquar paint used for painting the samurai swords.
2) The second word I have trouble with is the word enemal. In translation it is like paint that you can use for painting your central heating system. It is a paint that can stand heat and must be heated to really bake in the surface.
For now I just bought some one shot to be safe, but there must be some Dutch brands (AKZO is Dutch) that have the same chemical foundations. But I would really like to know and understand what it is, that makes it so special.
Realizing we are in the 2nd renaissance of the arts.
Learn, copy and trying to improve...
Still in the learning phase ;-)
Amsterdam Netherlands
www.ferrywinkler.nl
www.schitterend.eu
www.facebook.com/Schitterend.eu
Kent Smith
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Re: lead based paints

Post by Kent Smith »

In simple terms a Japan is a series of coarse ground pigments which have been ground in Japan varnish instead of oil or water. Japan colors can be mixed into many other mediums such as clear lacquer, shellac, many types of varnishes and alkyd (enamel) base resin. They also can be applied or rubbed into a surface, like a stain on wood, and topcoated with many types of clear. For example, "Japaned" furniture is stained with a Japan pigment color and typically topcoated with clear lacquer. Note that Japan paints and lacquer paints are always self solvent, even after curing. That means that they can be removed by the solvent from which they are made and will smear with additional applications of the same paint. They also dry, not cure, which means they are done when all the solvent evaporates. Of interest, water based latex also dries but does not cure.

An enamel is a paint that is one component, forms a finished protective film and is air dry. That means it is complete and no other additives are required for it to cure. "Long resin" enamels are used in high heat situations such as stoves, furnaces and other situations. They typically are less "oily" than other enamels. The shorter resins are like those in 1Shot for signs. The advantage of an enamel is that it is essentially "low tech" and can be applied in many different ways. It dries slowly enough to be worked until the finish will level properly and cover well. The other advantage is that enamels can be blended together on the surface as well as intermixed. With very little exceptions, alkyd enamels can be intermixed without much problem, even different brands. That is because the common ingredient is the alkyd resin which is only made by two or three companies and can only be made one way.

There are some water based and waterbourne latex "enamels" which are not really enamels. They are a latex which forms a finish that looks like enamel when dry. They do not have the same protective film and are classified as a coating instead of a paint.

As an aside, AKZO-Nobel is the worlds largest manufacturer of paints and coatings. Their specialty is two-component urethane systems such as Sikkens and house paints such as Nobel. They owned Chromatic sign paints for a few years but since it did not fit with their operations model, they sold it to 1Shot and as far as I know, do not make alkyd enamels.
erik winkler
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Re: lead based paints

Post by erik winkler »

I will make it.
Last edited by erik winkler on Tue Nov 29, 2011 7:05 am, edited 1 time in total.
Realizing we are in the 2nd renaissance of the arts.
Learn, copy and trying to improve...
Still in the learning phase ;-)
Amsterdam Netherlands
www.ferrywinkler.nl
www.schitterend.eu
www.facebook.com/Schitterend.eu
DAVE SMITH
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Location: ENGLAND

Re: lead based paints

Post by DAVE SMITH »

Doug Bernhardt wrote:........and I had been waiting to see some responses to this. A good question although I'm not sure running out and buying 50lbs. of white lead is a great idea. Smitty was working in his shop a few years ago and scraping the floor which had been done in lead paints. I think he was on his back after that for about 2 weeks......he'll jump in and be more clear.
You remember that Doug. That was 5 years ago now. I was scraping the old lead paint off the workshop floor without knee pads or jeans on just a pair of sporting shorts. Without protection I contaminated my leg with an infection possibly from the paint getting into an exposed cut .This caused me to have celulitus and needing a introvenous drip for 4 days which then kept me off work for 2 weeks hospitalised for 1, my leg ballooned to twice the size. Then 3 years later I did it again this time through my elbow after working on some property renovations .So my advice is wear knee and elbow protection next time you paint your workshop floor or do your house up .
Dangerous Dave...........
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