Driers for Oil Painting

[George O'Hanlon]

I am providing this information about driers used in oil and alkyd paint, because of questions that have arisen regarding their use.

In its broadest sense, a drier, or siccative, may be defined as any material that enhances the drying properties of oil paint. The oils used by painters, such as linseed, poppy seed, and nut oil dry by absorbing oxygen from the atmosphere. Driers are primarily viewed as oxidizing agents that accelerate the oxidation of oil.

Historically, driers were metallic compounds or pigments containing these compounds. Until the late 19th century, artists used umber, ground leaded-glass and smalt as driers. Until the 1860s, the metals most often cited as driers were lead and zinc. Rarely, copper in the form of verdigris was mentioned in literature as a drier. Manganese compounds were introduced as driers and were popularly used until the end of the 19th century. Cobalt driers were not used by artists until the 20th century.

Driers were used in the preparation of oil and in the preparation of separate mediums that were added to paint. They were also added in the tube to slow-drying colors. In damp and cold conditions, paint driers were used that may not be necessary when it is sunny and warm, so drier use varies according to the weather and the season. Driers are also used for underlying paint layers to hasten their drying prior to further painting.

Today, driers consist of metal salts suspended in solution that act as catalysts for hastening the oxidation and polymerization of drying oils and resins. Different metal driers each present different advantages and disadvantages in oil paint, but lead continues to be one of the most important driers in fine art painting, although there has been a trend among artists to replace its use with cobalt driers because of their lower toxicity.

Cobalt Driers
Cobalt is an extremely active drier and is one of the most widely used driers in paint, capable of being used alone as a single drier. It is primarily an oxidation catalyst and acts as a "surface drier." When used in excessive amounts it may have a tendency to cause surface wrinkling, hence it is important not to exceed recommend dosages. Cobalt is generally used in combination with other metals, such as manganese, zirconium and calcium. The quantity of cobalt drier used is very small, thereby minimizing any tendency to discolor paint. Cobalt does not discolor white paint as the deep blue color of the cobalt counteracts the yellow of drying oils and resins and can sometimes enhance the whiteness of paint. The unique feature of cobalt is that it is least affected by atmospheric humidity.

Manganese Driers
Manganese driers are intermediate in their activity and have both oxidizing and polymerizing properties. When manganese is used alone, it may produce hard and brittle paint films. When used in combination with lead, it produces tough and durable paint films. One disadvantage of manganese driers is their relatively dark brown color, which has a tendency to discolor white oil colors.

Lead Driers
For centuries, lead was the main auxiliary drier for air-drying oil paint. Lead is an effective, low-color drier. Lead is a through drier and is usually used in combination with cobalt or manganese. Lead drier improves the drying time of linseed oil and can yield pale and clear boiled oil. Lead in combination with cobalt and calcium is recommended, particularly for long-oil alkyds, since lead is the most effective drier. Lead helps to stabilize free radicals and coordinates to bring active sites into close proximity. These properties promote polymerization with the result that the use of lead driers produces hard, durable films. Lead is usually not referred to as a primary drier because its weak initiating properties make it impractical for rapid drying; hence, it is predominantly used with cobalt or manganese. However, it does possess some initiating characteristics that need to be taken into account. Lead driers are good wetting agents and so are absorbed onto the surface of pigments and fillers thus reducing their activity.

Some disadvantages of lead driers include its susceptibility to sulfur staining. Lead driers have relatively poor solubility in certain alkyd resin systems. Lead driers are generally incompatible with aluminum pigments and substrates. Lead driers suffer from "loss of dry" due to the formation of insoluble complexes with hydrolysis products when used with alkyd resins rendering it inactive. It can also be absorbed by certain pigments and fillers during storage. Lead is often overdosed in formulations to compensate for its "loss of dry" problems. However, some of the problems associated with lead driers, such as darkening with sulfur and reaction with polybasic acids can be overcome by including calcium.

Zirconium Driers
Zirconium is a useful and efficient auxiliary drier. Zirconium like lead acts as a through drier and is generally used in combination with cobalt, manganese and calcium. Unlike lead, however, zirconium is a poor pigment wetting and dispersing agent. Use of lead driers in combination with zirconium should be avoided.

When using zirconium to replace lead, usually the amount of cobalt needs to be increased by about 20% in order to compensate for the primary drying functions of the lead. It is also good to increase the calcium content in order to compensate for the way lead reacts with acids formed from unwanted hydrolysis, especially from alkyd resins. In high pigment volume concentration (PVC) paint, the amount of calcium may need to be doubled to compensate for the pigment wetting properties lost by replacing lead with zirconium.

Calcium Driers
Calcium is an auxiliary drier that has little drying action in itself but is very useful in combination with active driers. In vehicles that show poor tolerance for lead, calcium can replace part of the lead to prevent the precipitation of the lead and maintain drying efficiency. Calcium is also useful as pigment wetting and dispersing agents and helps to improve hardness. When used with drier-adsorbing pigments, calcium minimizes "loss of dry" by being preferentially absorbed by these pigments.

Concentrations of Metal in Common Driers are expressed as a percentage of the liquid drier. The most typical amount of metal in drier used for fine art purposes is indicated in bold.

Cobalt-based metallic driers 6, 8, 10, 12%
Manganese-based metallic driers 6, 8, 9, 10%
Lead-based metallic driers 24, 30, 32, 36%
Zirconium-based metallic driers 6, 12, 18, 24%
Calcium-based metallic driers 4, 5, 10%

For most artists' oil and alkyd paints, I recommend a blend of cobalt 6%, lead 36% and calcium 10% at 0.5% of the weight of the oil and alkyd resin content of the paint. For most artists' paints, this means about 1 gram for every 400 grams of paste paint. A similar drier without the use of lead may consist of a blend of cobalt 6%, zirconium 24% and calcium 10%.

[George O'Hanlon]

We will be soon offering a line of driers for artists' use in oil paint. The new driers will be available January 2008:

Lead-Cobalt-Calcium Drier
Lead-Cobalt-Calcium Drier is a concentrated blend of metallic driers designed to improve the drying of oils and alkyds. This blend is optimized for use in all artists colors.

Zirconium-Cobalt-Calcium Drier
Zirconium-Cobalt-Calcium Drier is a concentrated blend of metallic driers formulated to improve the drying of oil and alkyd paints. This blend is optimized for use in pale and white artists’ colors.

English Patent Drier
English Patent Drier is a white paste drier based on original 19th century formulas. The blend of lead and manganese driers can be added without critical measurment—1 in 12 parts oil color.

French Terebine
French Terebine is a liquid drier made with lead and manganese in linseed oil with copal and thinned with turpentine. Our terebine is based on the original 19th century formula improved by using purer ingredients. Add to oil colors to decrease drying time at the rate of 1 to 10 parts. Lead, 1%; Manganese, 0.05%.

English Terebine
English Terebine is a liquid drier made with lead and manganese in linseed oil and thinned with odorless mineral spirits. Our terebine is based on the original 19th century formula improved with purer ingredients. Add to oil colors to decrease drying time. Lead, 1%; Manganese, 0.05%.

Siccatif de Courtrai
Siccatif de Courtrai—The original drier and not a modern version of the famous lead and manganese drier in turpentine.

Siccatif de Harlem
This is the original formulation and not a modern version of the famous recipe for Congo copal dissolved in linseed and spike oil. Although not strictly speaking a drier, it can be used to hasten drying and add tough copal to the paint film.


Your feedback is requested! I am interested to get feedback on which driers may be of interest and those that would not be to painters.

[George O'Hanlon]

We may also simply package the lead, cobalt and calcium driers separately for individual experimentation and for use in paint making. Adding calcium drier while grinding paint can aid in pigment dispersion and improve its drying performance if driers are added while painting.

[Orp]

My vote goes for the most idiot-proof formulation. The whole idea of adding little crucial amounts of drier worries me, so the English Patent Drier looks pretty promising.

[arcticpost]

Siccatif de Harlem & French Terebine primarily due to my interest in copal. Well, English Patent Drier as well...though I'm sure each could be found useful.

[bart johnson]

I like the idea of paste better than a liquid. One of the reasons I like the oleogel is its gel form. More controllable when things aren't dripping or running.. Also a simple 12 to 1. The siccatif de Harlem sounds good as well. Those would be my first two choices.

[George O'Hanlon]

Here is our revised list of driers:

Calcium Drier is a clear, amber drier containing calcium, which activates the natural drying characteristics of pigments and aids in wetting pigments when grinding colors. Add 1 or 2 drops per 5 ml (teaspoon) paint.
Available now

Zirconium Drier contains zirconium and calcium salts to give greater drying power than Calcium Drier. May be mixed directly with oil colors or thinner by adding 1 or 2 drops per 5 ml (teaspoon).
Available now

Cobalt System Drier is a concentrated blend of cobalt, zirconium and calcium salts. Use in small doses by adding drop-by-drop to oil colors. Provides well-balanced drying of oil paint, both on the surface and through the film with no effect on the hue or gloss.
Available now

Lead Drier is a concentrated blend of lead, cobalt and calcium designed to improve the drying of oils and alkyds. This blend is optimized for use in all artists colors. Contains Lead
Available February 2010

English Patent Drier is a paste drier based on original 19th century formulas, containing lead and zinc driers that can be added without critical measurement—1 part drier to 10 parts oil color. Contains Lead
Available now

English Terebine is a liquid drier made with lead and manganese in linseed oil and thinned with odorless mineral spirits. Based on the original 19th century formula and improved with purer ingredients. Add to oil colors to decrease drying time. Contains Lead
Available April 2010

French Terebine is a liquid drier made with lead and manganese in linseed oil with copal and thinned with turpentine. Based on the original 19th century formula and improved with purer ingredients. Add to oil colors to decrease drying time at the rate of 1 to 10 parts. Contains Lead
Available April 2010

Siccatif de Courtrai is a reproduction of the famous 19th century lead and manganese drier in turpentine used by William Bouguereau. This drier is based on gold size recipes, because our research indicates that this popular drier was a type of japanner's gold size. Contains Lead
Available April 2010

Siccatif de Harlem is based on the famous “siccatif” of copal dissolved in linseed and spike oil. Not strictly speaking a drier, it can be used to hasten drying and add hardness to paint.
Available April 2010

[ 27. January 2010, 11:36: Message edited by: Admin ]

[Gus]

George, I liked the English Patent Drier but fairly quickly it starts getting lumpy, I would think from opening the can. Would it be better to tube it?

[George O'Hanlon]

When you say it starts to get lumpy, can you describe this in more detail so that I can understand what is happening? Is it lumpy throughout or is it on the surface? Is this lumpiness caused by skinning? Do you leave the can open for long periods?

[veng]

would the calcium drier work along with the amber gelling medium sold by groves? I perfer to have paint on the long side would this have any affect on that?