All about oil paints, mediums and cleaners that are safe to use and free of volatile organic compounds.
I make my own oil paints. I've been studying paint making, doing tons of research and testing samples vigorously. Now it's all I use, my own paints. I don't like store bought paints and don't use them anymore. It's partly because of aluminum stearate which is added to most of them. It's a greasy slimey additive, a type of wax, extremely light so lots may be added thereby diluting paints very effectively. I won't use it in my paints. It's a cause of degradation of oil paints over long periods of time, this according to conservationists. Something about breaking down into soap from exposure to our atmosphere. All aluminum additives should be avoided. Better additives can be used but they're more expensive.
I've tried deformulating the pigments out of some store bought paints. A certain brand of viridian contained very little pigment but lots of dyes. Viridian is a very difficult pigment and it's expensive. But most of the store bought paints were OK, maybe a little low on pigments, high on oils. I sometimes wonder how well these manufacturers test their products. Some colours never seem to dry, staying sticky forever it seems. The pyrolle reds in particular can have this drying problem. My paints must dry properly or I won't accept its formula and will try something else until it does. I'm not opposed to the use of additives and think its silly to be a puritan that insists on pure linseed oil and pigments only. Very few pigments make good paint this way.
Pigments are chemicals and each one reacts differently when mixed with oil. It's taken many trial and error paint making sessions to end up with good paint. Additives are always needed. Without any additives, just using linseed oil and pigments, the paint will work but barely. I'll pass on my insights into the problems of paint making with each formula.
Before I Start
If you would prefer to simply buy my paint rather than attempt to make it yourself, please visit my shop.
The paints I sell use these very same basic formulas but they also have a few advanced additives and processes that are complicated and expensive but well worth the extra effort.
Let's start with titanium white paint, the only white I use. It's a very cheap pigment, 1 kilo has lasted me 3 years. On its own as a powder it's not completely safe so wear a dust mask. See the MSDS. Most loose pigments are not safe, however, once they are coated in oil they become safer and once dried in a paint film they become very safe.
You will need these oily ingredients;
-cold pressed artist grade linseed oil
-cold pressed, washed safflower or sunflower oil that is high in omega 6 and a little omega 3 ( I'll explain the washing)
-alkyd resin, solvent-free (I'll explain drying out alkyd resins)
And these dry ingredients;
-titanium white pigment
-calcium carbonate, aka whiting
The Oily Ingredients
The unique difficulty with white paint is that if it turns yellow later your painting is ruined which is exactly what happened to me in the beginning of my paint making journey. My pristine white snow turned into the dreaded yellow snow in Frank Zappa's song,
"WATCH OUT WHERE THE HUSKIES GO
AN' DON'T YOU EAT THAT YELLOW SNOW"
After that I smartened up and the snow stays white now. I learned that no matter which linseed oil I used, they all turned yellow. I have the tests to prove it. In fact the oldest samples are now orange.
Regardless of this yellowing, linseed oil dries to a tough paint film. How could I prevent this yellowing? I looked at other paint oils and found an answer. Safflower oil did not yellow nearly as badly as linseed but it didn't dry as well, remaining sticky and soft. So I tried mixing safflower oil with linseed oil and it makes a paint just as tough as straight linseed oil does but without the yellowing. The proportions of linseed and safflower (or sunflower) oils is important.
When buying safflower or sunflower oil for paint making be sure to look at the label. If it states it is "high-oleic" don't buy it as this type of oil will never dry. It must be high in omega 6 (linoleic) and with a small proportion of omega 3 (linolenic). Find a cold-pressed organic brand if possible. They will most likely be expensive European brands.
Washing the Oil
Linseed oil can be purchased at any art supply shop or at a linseed oil supplier such as Allback. I buy mine at a feed mill, Nobleton Feed Mill out in horse country where it is sold as cold-pressed flax oil used for horse ailments, then I wash it. Flax and linseed are the same thing.
Safflower or sunflower oils should be tested first as it may be poor quality and cause yellowing. To test an oil, smear several drops on a pre-primed little square of canvas and set it to dry where there is lots of light like a window sill or under some fluorescent lighting. It takes about 6-8 months for the yellowing to show so you must wait. Paint makers need to have great patience! I'll discuss UV fluorescent lighting as a means to speed up paint drying tests later on this page.
Unwashed oil always yellows more than washed oil so always wash it.
To wash your oil find a large enough container like a gallon jar, pour in your bottle of oil and add twice as much water so 1 part oil to 2 parts water. Now mix it all together really well, let it sit and repeat. Do this on and off for a day. You can leave and come back to it at any time so no worries. What is happening is the water soluble components of the oil are being sopped up by the water but it takes time. The water is absorbing the mucilage, glycerin, chlorophyll, waxes and such which cause raw oil to yellow. Let it sit for a week.
A slimey milky layer will have developed between the water and the oil. We do not want this byproduct so remove the oil but leave this byproduct layer alone. Use scoops or siphon off the clean oil only. Now dispose of the water and its byproduct and refill the jar with the same oil and more fresh water. Repeat the whole process. Expect a loss of about 30% which is the byproduct being removed from the oil. Once the byproduct stops developing or is much reduced, perhaps after 3-4 sessions, leave the oil in your jar with clean water underneath. This is how it is stored, over water. The water will continue cleaning the oil and you can scoop off oil whenever you need some. Leave an inch of air space on top and put the lid on lightly, so that it allows air leakage. Place the jar where there is plenty of light. Paint oils darken in the dark and lighten in the light. The sun created them so they are most harmonious in the light.
Drying the Alkyd Resin
To further improve the formula's non-yellowing qualities all my paints contain a small proportion of alkyd resin. Alkyds prevent yellowing and they also help the paint harden evenly throughout with less skinning over. You'll appreciate this quality at your pallete as it means that the paint can be reused more often.
The problem with alkyd resins is that they have solvents in them and we do not want solvents in our studios. Into an oversized jar or pail pour an inch or 2 of the alkyds and cover the top with some mesh to keep bugs out, then set it outside. Stir it from time to time and smell it to see if the solvents are dissipating. It may take a day or more to become usable depending on the temperature and humidity. In winter it takes a few weeks. If you wait too long the resin will gel and it could be ruined so be observant. A little thickening with less solvent odour is what you want. Long strings from the stir stick instead of drips means that it's ready.
Mix this dried alkyd resin with some linseed oil at about a 1 to 1 proportion and store it this way, mixed in oil. If you try to store the dried alkyd resin alone it will probably over-thicken and become a useless jelly mess. The solvents were in it for a reason! They prevent run-away polymerization. Alkyds can be treated the same as oils but they polymerize faster and yellow much less over time. Not all alkyds are the same. My favourite is good old Penetrol from the house paint store. After many tests it reigns supreme.
The last oily ingredient to be mixed into the basic paint oil is soya lecithin, a wetting agent and emulsifier. It helps the pigment particles become well coated in oil while the paint is being made. This means that less oil is required and a better consistency of paint can be made with less effort. It just flows better! Less oil means less chances of yellowing in the long term. It prevents the oil from separating from the paint later and creates a more flexible and waterproof dried film. Lecithin dries to a tough film just like the oil but more slowly. It's a dark substance but it doesn't darken more over time and a very small amount is all that's needed. A small percentage is added to all my paints. It's available at Bulk Barn. Store it in the light with your oils. It will lighten over time.
The Dry Ingredients
There is something about the chemistry of titanium dioxide that is synergistic with safflower oil. They help each other stay bright and white. An important additive, zinc oxide, also helps. In concert with titanium dioxide, it brightens and holds the white as well as hardens the paint film. But there is a problem. Zinc, like aluminum, decays into a soap in very old oil paintings. Do not use straight zinc white paint on your "museum quality" paintings! You'll be cursed by conservateurs in 100 years. In spite of this we can use a tiny percentage in the formula. It is used in all my paints and is unnoticeable due to it being a weak tinter.
Calcium carbonate for paint making is also known as chalk but it has many forms such as whiting, calcite and marble dust. It has a bad reputation as a cheap filler often used in student grades of store bought paints. Although this is true it is still a helpful additive in oil paints for a variety of reasons. It has been used in paints for hundreds of years so we know it lasts. Calcium helps with through drying. Paint dries more evenly through-out with less skinning over. Skinning over slows the through drying of paints by sealing out the oxygen it needs to polymerize into a hard film. Calcium carbonate also stiffens a runny paint. It also tempers an overly powerful pigment such as phthalocyanine blue and green. I use it sparingly, just enough to make an improvement.
Preparing the Oil
The oil is a mixture of 10% linseed oil, 70% safflower oil and 20% dried alkyd resin. Add the lecithin over and above this at an additional volume of 4%. So if you've made 100 ml. of oil mix, add 4 ml. of lecithin. Stir it up well.
Preparing the Dry Ingredients
Put on your dust mask and make a small pile of titanium dioxide pigment on a large porcelain tile or glass grinding slab. More on the grinding slab later. A pile with a volume equal to a hockey puck (I'm Canadian!) is plenty. Measure out an additional volume of 4% zinc oxide. Also measure out an additional volume of 10% calcium carbonate whiting or chalk. The way I do this is I form my pile of titanium pigment into a round pie shape, then divide it into 4 slices, each being 25%, then divide one slice in half, 12 1/2% each and in half again to about 6%. I eyeball the zinc and calcium piles to approximately match the appropriate pie slices making adjustments as I feel is necessary.
Now, using a large palette knife, fold all the dry powders into each other so they are well blended. The dry ingredients are now ready to become paint! Isn't this exciting!
Mixing the Paint
Slowly add oil to the dry ingredients while mixing it together. It must be a thick clumpy mass with as little oil as possible added and yet it must not have dry powders unmixed. Much like making bread. This mass is now kneaded and worked. It will become stickier as you progress. Now it must be mulled. A muller is a flat-bottomed tool that squeezes down on the paint as it is worked back and forth. Some call this process grinding rather than mulling. Mull until the paint has reached the desired consistency, more mulling is better than less. Now apply a sample of the paint onto a small square of primed substrate like canvas and place it in a bright spot to dry. Cover the paint pile with cling wrap and leave it. It's consistency may change after a day. Check the sample to see if it is drying and if it has good form. Check the paint pile to see if it has firmed up or melted. Add oil or more dry ingredients to adjust it if necessary and repeat the sampling/cling wrap process.
Your paint is ready to be used! It is fun at first but paint making is a chore after hundreds of batches. I like doing things myself so it suits me well. I also use a power muller...more on this drill attachment later. Better paint with less effort!
Thickening of Safflower Oil in UV Light
This is a tray of safflower oil being thickened directly under a UV lamp. The UV lamps are as effective as direct sunlight. It will take a month for this oil to be as thick as honey. Thickened safflower oil is less yellowing than linseed oil. I use it to add more sheen to my paints and it also helps emulsify my Hybrid Paint Reducer. Thicker oils tend to stay emulsified whereas thin oils may need constant remixing.
Always add a small percentage of linseed oil to any of the semi-drying oils such as safflower, sunflower or soybean. Approximately 10% linseed is usually enough. This will fortify the dried film while maintaining clarity and it won't be sticky.
A UV light chamber that is enclosed needs to be ventilated because the lamps create ozone, a fire hazard. Read about these UV lamps and study what the reptile hobbyists do in their terrariums. Read more here and here.
These lamps as used for reptiles are only dangerous if you get too close. They are like miniature suns. Turn them off when you are near them.
Let's start with a simple formula for cleaning brushes. It's completely safe and non-toxic. You'll need 4 ingredients in these proportions;
-5 parts water
-1 part vegetable oil
-1 part potassium oleate
-2% epsom salts (2ml. per 100 ml of the formula)
Potassium oleate is a type of gel soap used by potters as a mould release coating and in cosmetics. Buy it at psh.ca or save on smaller jars at my shop page. Here's the MSDS sheet. The oil is simply sunflower, safflower or whatever you have for cooking in your kitchen.
Mix the oil and potassium oleate together. Next add the water and stir. Potassium oleate is completely soluble in oil and in water but in water it dissolves very slowly. It may take a day or so to become fully dissolved.
The brush cleaner can now be used but it will need to be remixed often as it will try to separate into a creamy white top layer over a clear bottom layer. Help it to stay emulsified by adding 2% by volume of epsom salts. That's about half a teaspoon per 100 ml. of the brush cleaner. It will thicken up to a creamier consistency and the formula should remain emulsified for a much longer time. Too much epsom salts causes it to revert back to a thinner consistency so experiment in tiny increments.
Just dip your brush into the cleaner and work it in, then wipe it off and repeat until the brush is clean. This formula will wash off in water, but I like to simply wipe it off really well and shape the bristles. It helps to condition them as well.
If you would prefer to simply buy my brush cleaner rather than make it yourself, please visit my shop.
Wash & Glaze Medium
This medium is the ideal solution to the problem of thinning oil paints without using any toxic solvents such as turpentine or the other VOC based thinners. This particular formula is meant to be used as a wash or glaze and is not suitable for reducing paints that are too thick such as is often done at the palette. For reducing thick paints another similar formula is used, Hybrid Paint Medium, I'll be describing it later.
This medium is designed for the addition of a very small percentage of oil paint which creates a thin transparent wash. It needs to be mixed with the paint well and mixes slower than it would with turpentine, but with no fumes at all. It's formula is based on pure acrylic mediums and safe, non-toxic solvents and surfactants. Surprised?
Oils and acrylics and alkyds have been formulated together in paints for decades now. Chemists have been moving away from VOCs and trying to improve paints and they have become very successful at it. My formulas use the same basic chemistry principles. This is nothing new to a paint chemist.
The Wash and Glaze Medium is ideal for creating acrylic paint washes too and is completely compatable with acrylics.
If you would prefer to simply buy my medium, visit my shop. The formula does require some specialized chemical materials.
To make just over 125 ml. (1/2 a cup) you will need these volumes;
-100 ml. acrylic medium, best quality, gloss
-25 ml. propylene glycol
-2.5 ml. carboxymethyl starch
-2.5 ml. sodium lauryl ether sulfate
-1.8 ml. soya lecithin
-1.25 ml. potassium oleate
The Mixing Steps
1)- First mix the acrylic medium with the propylene glycol.
2)- Add the carboxymethyl starch and stir. It will be lumpy. Let it sit for a day or so stirring occasionally until the lumps are gone.
3)- Mix together the sodium lauryl ether sulfate, lecithin and potassium oleate.
4)- Mix it all together, stirring occasionally for an hour. It improves over time.
It is ready to be used. This medium has freed me to regularly use oil-based washes without worries about toxic fumes and it is a joy to apply. It seems to glide on the surface. Washes can be layered on top of each other much the same as watercolours. It initially dries to firm film quickly but hardens slowly becoming fully cured in a few weeks much the same as oil paints do.
Buying the Chemicals
My favourite acrylic medium has been Tri-Art Finest Quality Polymer Medium- in the Gloss sheen, made here in Canada. It's a 100% acrylic polymer emulsion. There are other brands but they don't disclose their formulas so who knows what they contain. Some may contain vinyl (PVC) which is OK but not as tough as pure acrylic.
Propylene glycol is used in many ways from RV antifreeze, food additives, vape inhalers and for horses digestive tract problems. It's the safest solvent there is next to water but it doesn't work the same as VOCs do. I bought mine at the Nobleton Feed Mill.
Carboxymethyl starch is a modified food starch used in vitamin capsules, as a food thickener and it is also used as wallpaper paste. It helps with adhesion and emulsification. Zinsser makes a brand called All-Purpose Adhesive & Wall Size available at Canadian Tire stores. Starches have been used as paint ingredients for centuries.
Sodium lauryl ether sulfate is a surfactant. It is a common ingredient in cosmetics and is available at Aquatech Skin Care.
Potassium oleate is a gel soap available at PSH.ca . It is described in the "Brush Cleaner" formula up above. Soaps are also surfactants. More about surfactants later...easy does it, more is not better.
Hybrid Paint Medium
The Hybrid Paint Medium is designed for thinning down paints to a desired consistency while fortifying the paint at the same time. It's typically used at the palette while painting. The Hybrid Paint Medium can be added to your paint at any proportion. If the paint needs to be thinned for a wash or glaze use the Wash & Glaze Medium. It has the consistency of slippery hand lotion.
The formula combines 4 different paint mediums. Oils, alkyds, acrylics and starches. Alkyds greatly enhance the oil's clarity and drying power. Acrylics are used as a non-yellowing co-binder and modified starch greatly improves the adhesion and emulsification of the complete formula. The balance is critical and after much testing this is it! I'm very happy with the performance of my paints while using the Hybrid Paint Medium.
It can be used directly as a paint making medium on its own or mixed with any proportion of paint oil.
In acrylic paints the Hybrid Paint Medium slows drying and adds the properties of oil paints. Mixing the hybrid medium with acrylic paints is fine. The Wash and Glaze Medium is suitable for thinning down acrylic washes too.
This formula can be difficult with problems arising which may need an experienced formulator to rectify so if you would prefer to just buy some go to my shop page.
The formula consists of;
-1 part paint oil, as used in White Paint
-1 part burnt plate oil #3, from Graphic Chemical, print makers use this
-2 parts dried alkyd resin, dried, as used in White Paint
-4 parts Wash & Glaze Medium
Mix the paint oil, burnt plate oil and dried alkyd resin together. Add the Wash & Glaze Medium. Stir well but gently, not faster than 150 rpm, for one hour. Remix or shake the bottle before using.
Shop is now open!
Updated July 10th, 2017. Scroll down for the latest...Paint Additives are essential... Soybean oil for white paint... How to make quicklime from hydrated lime.
These hybrid mediums are a modern alternative to the stuffy old ways of traditionalists who say that oils and acrylics don't mix. All of the painting mediums can enhance each other if formulated properly.
A review of Old Masters formulas actually shows many examples of hybrid emulsions in oil paintings such as the use of egg yolks, starches and milk protein casein with oils.
In today's world the most advanced paints of superior film qualities are made using modified oils, alkyds, acrylics and cellulose starches without VOCs. My mediums are not that new nor are they unique. This level of paint technology has been developed for the past 30 years or more.
The question that often arises is of a paint's archival qualities...will it last? If a paint formula is new, how can we predict what your painting will be like in 100 years. It's not really possible to predict a paintings condition even in 20 years. There are a myriad of variables to consider.
What can be done to help us predict our paint or medium's performance is testing. Does it dry well on canvas, on glass or on palette paper? Does it peel off easily or is it well adhered? Test it thick and thin. Keep all the samples and watch them over the years, especially the whites. Keep them in a well lit environment. A dark drawer is not good unless your art is terrible and will be hanging in the dark too. Actually darkness is a good way to test for yellowing. Just remember to bring your samples into the light for a truer evaluation of actual conditions.
My samples are on flexible substrates so that shrinkage can be observed. The sample will curl rather than stay flat if the shrinkage is great. Observe the sample's dryness, sheen and hardness. Brittleness can be an issue. A soft film may crumble or soften more in hot weather after aging.
Remember that many Old Master's artworks would not have survived if not for the work of art conservators. Some very famous artists were notorious for their badly formulated paints and mediums and all the established manufacturers of artist's paints have made mistakes over the years.
We will make paintings that last for 500 years...don't worry:)
More testing tips coming soon...
How sticky can you get? A glue or a paint oil?
It would seem at first glance that soybean oil would make an ideal paint oil for artist's paints. It has a reputation as being non-yellowing. Its FATTY ACID COMPOSITION has a good amount of linoleic acid (or omega 6) at about 50%. It has some linolenic acid too (omega 3) at 6-9% which is not typical of semi-drying oils. But it also has about 25% of oleic acid (omega 9) which only thickens, never drying. However oleic acid can contribute more non-yellowing factor as well as more plasticity. It's a balancing act with these fatty acid profiles.
It has an iodine value of approx. 130, similar to safflower and sunflower. In my UV chamber which mimics direct sunlight, the oil dries in 2-3 days thin, 5 days thick. Unfortunately it is very sticky. Some stickiness is acceptable because when semi-drying oils are mixed with the pigments they usually dry tack-free. The problem is that it does not dry well even in pigment mixtures. In titanium white pigment a thin coat is fine but thick coats tend to stay wet for weeks. Safflower and sunflower do a better job drying in titanium white pigment.
The reason soybean oil is popular with large scale paint manufacturers is probably due to its low cost and its low yellowing factor. It is modified by them to suit their paint or alkyd formulas. The commercial paint chemicals market have every conceivable modification of plant oils imaginable yet one thing is not possible, to make linolenic acid non-yellowing. It must be blended into other non-yellowing drying oils or resins to be acceptable. Yes, it can be molecularily modified but then it is no longer linolenic acid but is something else. Some artists claim to be able to create non-yellowing linseed oil by a lengthy process based on centuries of knowledge but my suspicion is that the fatty acid profile has been modified and the highly yellowing linolenic acid has been diminished. In my tests of a typical Old Master's process, old well washed linseed oil stored in UV light and with the addition of a small amount of lime for 2-3 years does become less yellowing but it has also gained a tiny amount of tack. Regardless, this is still a superior paint oil, just not as tough a film as when freshly washed 2 years earlier but less yellowing and in fact matching the yellowing of safflower oil.
The Power Muller For Paint Making
It is important to mull your paints well. It is a lot of work but good paint is worth it. Poorly mixed paint will have all sorts of problems some of which arise later after it's tubed. Poorly made paint is not as beautiful as well made paint. It is always better to mull more than less. In the beginning I was mulling my paints by hand using a glass muller but I quickly realized that this was slow and too much work. One batch of paint took half a day to make properly.
Necessity is the mother of invention they say and so this is the result of my laziness, a power muller! It is an attachment for a power drill. It requires a powerful drill of a minimum of 5 amps power rating. It requires a very slow speed as well but most drills are too fast. The solution is to use a speed reducer. If the speed is too fast it will fling paint everywhere making a big mess and you will not develop an intimate connection with the process.
This is one of many muller attachments that I have devised. It is a white glass version which is non-marring and is used for white and light paints only. I also have stainless steel versions which do mar but are fine for colours. The bowls must have flat or almost flat bottoms. This bowl broke once so buy extras. If it breaks chip away all old glass, apply silicone caulking and remount the new bowl. The shaft is embedded into an epoxy filler. My epoxy shrinks stressing the bowl and leaving some gaps but these gaps can be filled afterwards. Silicone rubber is maybe better. The shaft has a 90 degree bend in the filler to lock it in. Spend some axtra time getting the shaft straight.
The process is to mix the pigment/oil/additives as thickly as possible by large palette knife and then use the power muller. The paint pile will thin out usually and will need adjusting with more pigment/powder additives or maybe more oil/medium. Make a sample on some substrate and allow it to dry while the paint pile rests. Cover the paint pile with cling wrap. Usually the pile changes consistency after a day or so and will need more adjusting. Also check on the sample to see if it is drying well and has a good shine.
The power muller allows you to make several batches of paint in a day. It mixes paints very well and you will appreciate its time-saving benefits while creating excellent paints. It takes some practice to learn to control a drill in this upright position but in a day you will be experienced.
If you would prefer to buy a power muller attachment for your drill I am selling a smaller version suitable for smaller amperage drills. It is available here on my shop page. In my opinion this smaller sized version is actually better because it is easier to control.
My larger version in action...
Washed Linseed Oil Samples, 2-3 years old. Stored in light 12 hours per day.
Washed Safflower Oil Samples, 2-3 years old. Stored in light 12 hours per day.
The soybean oil may still be acceptable by my standards because I would never use a semi-drying oil on its own to make my paints. My paint oils are formulas of approx. 10-20% linseed oil, 10-20% dried alkyd resin (which is a soybean oil derivative) and the balance of 60-80% made up of safflower or sunflower or even the soybean oil. The strategy is to minimize yellowing while maintaining film strength.
The next test for this soybean oil is the 8 month test. At about that time yellowing and weeping starts to show itself.
An update on soybean oil. Zirconium drier at a high dose helps it dry with much less tack. Cobalt drier helps it dry faster but does not remediate the tackiness so zirconium drier is best.
Soybean Oil White Paint
In a titanium white paint mix using soybean oil, it dries non-tacky in 4+ days with a nice sheen, hard and smooth. Without any driers it is slower drying but adding a small proportion of linseed oil helps it greatly. I will be watching this sample. My early senses tell me that it is the least yellowing of all the oils and it may become my main oil for making whites. The slow drying is preferable to me and my way of painting.
I purchased the oil at Aquatec Skin Care. The oil is meant for cosmetics so it contains all the natural and healthy components of soybeans but for paint making we do not want these ingredients so be sure to wash the oil first as mentioned in "Washing the Oil".
How to Make Quicklime
Quicklime is calcium oxide. It is very hard to find a supplier of quicklime simply because it is difficult to store. Quicklime is hydroscopic which means it absorbs moisture from the air and eventually becomes hydrated lime a.k.a. calcium hydroxide. Quicklime was used as an oil additive by some of the Old Masters. It was added along with calcium carbonate (chalk) to jars of linseed oil during long term storage to help reduce acidity. More details regarding the proportions I've tested are coming...
Quicklime is also recommended as an anti-tack additive for soybean based oil paints according to older 1960's articles. In my early tests it seems ineffective although perhaps it needs to steep in the oil for a long period of time. Zirconium driers are very effective at 7% by volume added to soybean oil.
Make quicklime from regular lime purchased at a builder's supply. Use a stainless steel dish of some sort to hold the lime. Do not use iron, steel or aluminum. Iron and regular steel will contaminate the final product with iron oxide and aluminum will melt. Place about a tablespoon of the builder's lime into the dish. A small amount for now will help you to understand the process. Using a plumber's torch, heat the metal until it is glowing red hot. This is the correct temperature for the water which is chemically bound to calcium hydroxide to be driven off. You can watch the powder boil as the water leaves. It is losing about 40% of its weight, becoming light and fluffy. Stir the powder with an old screwdriver as the heating process progresses. Once the powder stops boiling it is ready. It takes about 5 minutes. You now have quicklime aka calcium oxide.
Quicklime is very caustic so be safe and cautious handling it.
When To Use Additives? This is my list of the additives I always use in my paint formulas;
Dried Alkyd Resin- always added into the paint oil, 10-25%. Toughens film, prevents tackiness and reduces yellowing. Dries fast & well in paints. Essential when using semi-drying oils to prevent age induced softening. Non-toxic after removal of VOC solvents.
Lecithin- always added into the paint oil, 3-5%. Use the soy type, sunflower lecithin is not suitable. An emulsifier, wetting agent and suspension stabilizer. Waterproofs paint film. Especially helpful in Phthalo paints. Helps drying.
Helps emulsification of hybrid paint formulas.
Cetyl Alcohol- always added into the paint oil, 0.5-0.85%. This is a type of wax. The oil must be heated to 50 C. Too much causes stiff paint. Helps paints dry evenly and helps prevent stringy paint as in ultramarines. Evens the consistency of difficult pigments. Sold at cosmetic materials suppliers such as Aquatech Skin Care. Helps emulsification of hybrid paint formulas.
Calcium Carbonate- always added, 5-25%. Helps drying, bulks up paint if too runny but adds slight grittiness. Lightens colour slightly and opacifies. I like Snowhite Whiting.
Zinc Oxide White PW4- always added, 5%. In whites adds more
whiteness. Very synergetic in titanium whites adding to film toughness. Helps all paints dry and harden better.
Zirconium Silicate- always added to all whites and all colours at 5-100%. Titanium dioxide white & zirconium silicate work very well together, add 5% (too much affects whiteness). It is pale beige coloured but a very weak tinter. Toughens film and adds flexibility. Helps drying. No limit, excellent as a mixing paint on its own. Buy it at a potter's supply.
This is my list of the additives I sometimes use in my paint formulas;
Aluminum Hydroxide PW24 (aka alumina hydrate). A fine filler, tint reducer, transparentizer. Slows drying. Used in very strong pigments but maintains transparency such as with Phthalos.
Calcium Phosphate- Lowers acidity in stored oils.
Calcium Oxide - Helps prevent tack in oils, especially soy. Testing.
Burnt Plate Oil- melts thick paint, adds gloss. Good drier and anti-tack additive. Amber colour but non-darkening.
Fumed Silica- Makes thick mixes that are soft but preserves form, helps brushability and transparency. Flattens sheen. Excellent in phthalos. Paints remain brushable. Prevents settling. Prevents wrinkling of oil-rich paints.
In my new paints I now add the Hybrid Paint Medium in all my formulas. I mix the paint on the slab into a thick pile as usual but then I add about 25% Hybrid Paint Medium and remull the paint pile. It usually becomes thicker so add more of the hybrid medium until the paint seems a little too thin, then take a sample to test its drying power and cover the pile with cling wrap. The next day remix the pile with a large palette knife to test its consistency as it may have firmed up again. If it has firmed up too much, add more medium or more paint oil, remull the pile and retest. Experience and testing samples will tell you what's best.
This new paint is superior to the basic oil paints. It has an even drying power, dries well with less skinning over, and has a consistent texture regardless of pigments. It also dries to a better sheen than straight oils. It has a look similar to acrylics but a performance like oils.
For thick palette knife work add fumed silica and more Hybrid Medium.
Dreamy White Paint Formula...after years of trial and error this it! White paint with dreamy qualities.