Frequently Asked Questions.
Here we give answers to some questions from our customers.
- Pigment or Dye?
- Prilled Pigments
- Animal Glues
- Fluorescent and Phosphorescent Colors
- Color Pastes
- Pigment Color
- Pigment Suitability
- Pigments for Soaps and Cosmetics
- Drying of Oils
- Percent Data in Recipes
- Can Kremer Pigmente Linseed Oil and Walnut Oil be eaten?
- How much is 100 g?
2: How to …
- Dyeing with pigments?
- A pigment cannot be wetted
- Filling Watercolors into pans
- How do I get Oil Paint into the tube?
- How much Binder do I need?
- Difficulties when Dissolving Shellac
- Wooden Kitchen Countertops and Wooden Kitchen Utensils
- Oiling Exotic Woods
- Iron Conservation with Cosmoloid H 80
3: Cleaning tools and others
4: Storage and Safety
Pigment or Dye?
There is a widespread confusion about the difference between pigments and dyes.
Pigments are insoluble in solvents and water. Like fine, colored sand they can be finely dispersed in a binder, but the dispersion will appear cloudy.
Dyes dissolve completely in binders or solvents (like sugar in coffee) and form a transparent solution.
The particle sizes of dyes are much smaller than those of pigments. Dyes are in general less lightfast than pigments.
The XSL pigments, Irgazine® Orange DPP RA (23178), Irgazine® Scarlet DPP EK (23179), and some others have been prilled to avoid dust formation. Prills are small beads, like in washing powders. XSL pigments dissolve immediately when in contact with water, other pigments must be ground to break up the granules, e.g. Bristol Yellows (43101, 43111, 43131) Bismuth-Vanadate Yellow (43910, 43915, 43918, 43920) or Bone Black (47100).
Bone Glue, Hide Glue, Rabbit Skin Glue, Gelatine, and Isinglass are animal glues. These glues must first be soaked in water and then heated in a water bath. The heating temperature should never exceed 60 °C; otherwise the glue looses its elasticity and adhesive strength.
When cooling down, the glue will form a gel. Heating it will re-liquefy it.
Animal glue spoils quickly. The shelf life of glue solutions can be improved by keeping it in the refrigerator. It is possible to add 0.5% preservative, such as Biodocarb (78744).
Wall paints made with animal glue as a binder will permanently remain water-soluble. Old wall-paint has to be removed before applying new paint.
Fluorescent and Phosphorescent Colors
Kremer Pigmente offers a variety of luminescent pigments and fluorescent dyes. Basically they can be distinguished by the type of light effect.
Phosphorescent pigments are substances that glow in the dark after light excitation, no. 56500 – 56650.
Fluorescent pigments or dyes start to glow when exposed to ultraviolet light. These include the Daylight Fluorescent Pigments, no. 56000 – 56450, the Lumogen® Dyes, no. 94700 – 94739), the inorganic Fluorescent Pigments (not available any more) and also the Phosphorescent Pigments, no. 56500 – 56650 (phosphorescent and fluorescent).
A transparent binding medium is essential for an ideal behaviour.
Please take into account that UV-absorbers in your lacquer can reduce the fluorescent behaviour.
Color Pastes are pigments dispersed in water.
Some pigments, e. g. synthetic organic pigments, are difficult to grind with water. By grinding the pigment in a ball mill we can produce a much finer dispersion than by grinding the pigments by hand.
Using a Color Paste is easier, and the formation of dust is avoided.
The jars should always be well-closed in order to avoid the drying of the Color Paste. Color Pastes can only be used in water soluble binders; they are not suitable for solvent-based binders, oils or resins!
Our Color Pastes are sold by weight. The solid content (pigment content) is specified in the catalog. The Color Paste Bismuth-Vanadate Yellow (27160) contains an extremely heavy pigment, which settles during storage and has to be stirred before use.
The color of the pigments shown on your screen may differ from the real color, depending on screen settings, on light conditions etc. It is also extremely difficult to print authentic colors. Therefore we have decided to offer hand-painted color charts rather than printed charts.
The pigment color will also change in different binders. For example, most Green Earths make a very dark green oil color, while they remain relatively light in glue or watercolor.
The hue of a pigment is further influenced by light. This light effect is called metamerism. It is particularly distinctive in blue, green and purple pigments. The mixing of paints containing highly metameric pigments can be very difficult.
RAL or NCS color systems provide a good orientation, but give no information as to which pigments are present in these mixtures. Therefore we cannot assign and determine pigments to RAL colors.
Between 1910 and 1923/24 Hoechst developed a method to measure lightfastness by comparing the dyes with a indigo dyed standard. This method was originally developed for textiles. Lightfastness tests by comparison with the so-called wool standard are international practice today. This wool standard shows values from 1 (bad) to 8 (very good). The maximum value of 8 corresponds to the lightfastness of Indigo, therefore even if a substance is much more lightfast than Indigo it still has a lightfastness of 8.
Not every pigment is suitable for every application.
For example, Green Earth pigments are perfect for oil paints, for wall paints with glue, chalk or casein, but in acrylic dispersions or in silicates they will form lumps, coagulate or solidify.
Ultramarine Blue is very lightfast, non-toxic and stable in most techniques, but outdoors it will be destroyed by acid rain.
Synthetic organic pigments provide brilliant colors for many techniques, in mineral binders, however, they might be washed out by rain.
Cadmium pigments are prohibited for construction or industrial purposes. They produce toxic fumes if burned.
Please find a suitability list on our page Information and Recipes
Kremer Pigments for Soaps and Cosmetics
Our pigments, colorants and binders are intended for conservators, artists and craftsmen.
Kremer Pigmente does not supply products for cosmetic use.
We do not handle the products according to cosmetic standards and regulations, and some products can cause allergies when applied on human skin.
Drying oils such as Linseed Oil, Walnut oil and Poppy Oil dry by oxidation, i.e. absorption of oxygen from the air. This process is slow and can last days, weeks, months or even take years, depending on the type of oil, additives, dilution, film thickness and temperature.
The drying process is comparable with the cooling of freshly cooked pudding. A skin covers the surface while the pudding resp. the paint is still soft underneath. Thick paint may cause the skin to crack or wrinkle or may make the paint underneath to slide on vertical surfaces.
Percent Data in Recipes
The percent amount given in most recipes refer to the weight, rather than to the volume, e.g., a 15% solution of Paraloid B 72 consists of 15 parts by weight of Paraloid, and 85 parts by weight of Ethyl Acetate.
Can Kremer Pigmente Linseed Oil and Walnut Oil be eaten?
Products sold by Kremer Pigments are supposed to be used for conservation, art and other crafts. Oils bought from Kremer Pigments are not suitable for human consumption, not even natural linseed oil or walnut oil!
How Much is 100 g Pigment?
Kremer Pigmente sells pigments by weight, usually in bags of 100g and 1kg. Some products are even sold in smaller quantities.
We are frequently asked: “100 grams, how much is this?” 100g simply are 100g, but each pigment has a different volume per weight. 100g of Furnace Black (47250) will have 5 times the volume of 100g Terra di Siena. Therefore 100g of Furnace Black is not packaged in 100g bags, but in 1kg bags.
2: How to …
Dyeing with pigments?
It is not possible to dye textiles with pigments. Pigments are small particles. They do not dissolve and they do not adhere to the textile fibre. For this purpose one needs dyes like Cibacron dyes or natural dyes such as indigo, madder, or mignonette. However, one can produce paint from pigments and binder, and paint or print this on a fabric (see also: Pigment or Dye?).
A Pigment cannot be wetted
Synthetic Organic Pigments, Fluorescent Pigments, Van Dyck Brown or Milori Blue are not easily mixed with water. These pigments will behave like oil and float on top of the water. Alcohol (Ethyl alcohol, Isopropanol) or a wetting agent (e.g. Orotan 731 K (78032)) will reduce the surface tension and facilitate the use of the pigment.
Filling Watercolors into Pans
We offer empty watercolor pans for making your own watercolors.
To fill these empty pans, fill the liquid watercolor into a 10ml syringe (pharmacy or laboratory supplies), and then put a thin layer of watercolor into the pan. The color can be kept in the syringe. Allow each layer to dry before the next layer is added.
The recipe must be modified if the watercolor cracks during drying (too little binder) or does not dry (too much binder).
How to get Oil Paint into a tube
The filling and sealing of oil paint tubes is simple, but requires some practice.
Grind the oil paint into a thick paste. The paint should have the consistency of toothpaste.
Take off the cap of the tube. Put the oil paint onto a piece of wax paper and roll it up like a self-made cigarette. The paper roll should be small enough to fit into the back of the tube. Push the paper with the oil paint into the tube and lay it onto a board. Use a short round wooden stick, about the diameter of a broom stick and about 15 cm long, and roll it on the paper from behind, so the oil paint is pressed into the tube. Close the cap and flatten the end of the tube with the wooden stick.
Pull the paper carefully out of the tube. Flatten the end of the tube again, fold the metal (with help of a palette knife or spatula) to close the tube. Squeeze the folded metal firmly with a pair of pliers.
How Much Binder do I need?
Each pigment needs a different amount of binder. In oil-based binders there can be differences up to 300%, depending on the total particle surface of the pigment.
For example: Blanc Fix needs a very small amount of oil while Terra di Siena and Furnace Black need a lot of oil.
Difficulties when dissolving Shellac
Please check if you have used the appropriate solvent, such as Ethyl Alcohol, 99% (70800). Isopropanol is not as efficient as Ethyl Alcohol.
Shellac only partly dissolves in water-containing alcohols, the solution becomes cloudy.
Shellac should be stored in a dry and cool place. When exposed to moisture, shellac will no longer dissolve properly. Some types of shellac, especially the bleached, wax-free varieties, can become insoluble if stored for too long.
Wooden Kitchen Countertops and Wooden Kitchen Utensils
Hard-Drying Oil and Tung Oil Varnish or siccativated oils are generally unsuitable for the use on wooden kitchen countertops and wooden kitchen utensils. Countertop surfaces can chip and particles of the lacquer can end up in food. Linseed oil is not neutral in taste. Wooden countertops, cutting boards, etc. are best be treated with Walnut Oil (73500).
Oiling exotic woods
Kremer Pigments does not give recommendations for the treatment of exotic woods (Bangkirai, Merbau, Massaranduba etc.). Our oils are suitable for all common European woods, provided that resin pockets on larch etc. were treated properly.
Some exotic woods, especially rubber trees and related plants, may contain substances that prevent the drying of oils. The oil will remain sticky, stain the surface and the oil may not dry and stay in the wood for years (e.g. on wooden floors).
In such cases we definitely recommend preliminary tests on a sample board!
Iron Conservation with Cosmoloid H 80
Cosmoloid H 80 (62800) is a microcrystalline wax which is recommended for iron conservation.
Solve 20 g Cosmoloid H 80 in one liter of Shellsol T (70460). Dissolving the Cosmoloid H 80 can be accelerated by first melting the wax (at about 80 °C) and mixing it with the solvent afterwards. The solubility of Cosmoloid is improved by using aromatic solvents such as Shellsol A.
The wax solution has a milky appearance. This milky substance may settle at the bottom of the container after a while. Stir the solution well before using it.
The protection against corrosion is good, but the protective film is not resistant to abrasion.
3: Cleaning tools and others
Brushes used with aqueous binders or oil paints can be cleaned with Olive Oil Soap (78045). Olive Oil Soap restores natural oils to skin, brushes and bristles. It coats natural brush bristles with a protective layer of oil, leaving them smooth and extending their life.
Brushes used with acrylic emulsions should be washed immediately after use. Dried acrylic paint can be softened with Methoxypropanol PM (70920).
Tools used for synthetic or natural resins can only be cleaned with the appropriate solvents.
Cleaning Mortars, Marble Slabs and Mullers
We clean our own mortars, marble slabs and mullers with an abrasive cleaning agent or with marble dust and water. Tools soiled with materials like organic pigments or Milori Blue can be cleaned with Olive Oil Soap and a scouring pad.
Removing Stains from Clothes
Oil paints are best removed from garments by immediately removing the paint with a dry cloth, then washing it with water and soap (Olive Oil Soap, gall soap, Amytis); if possible wash in a washing machine as soon as possible. Commercially available stain removers can discolor some fabrics and textiles.
Dried acrylic paints can be softened or dissolved with Methoxypropanol PM, but bear in mind that Methoxypropanol PM can also dissolve the dye of the fabric and/or cause another stain.
4: Storage and Safety
Provided that pigments are kept dry and in a closed container they have no expiration date. If pigments become wet, they may agglomerate and will have to be ground before use.
Most of our pigments are supplied in 100g or 1 kg plastic bags. We offer PVC jars, glass bottles, polyethylene and metal buckets for storage containers.
We do pack pigments in jars (extra charge) on request.
Spontaneous Combustion of Linseed oil and other Drying Oils
Drying oils dry by reaction with oxygen. If you absorb linseed oil with a cloth or paper, the surface is enlarged greatly. This will speed up the drying process, which leads to a heat build-up and at the worst to spontaneous combustion. Therefore it is important to spread the cloth or paper soaked with linseed oil and let it dry in a safe place prior to disposal.
If you want to reuse the oil-soaked rags, etc. they have to be stored in closed metal containers.
Please bear in mind that spontaneous combustion is the main cause of fires in lacquer and paint factories, therefore do not underestimate the danger.
Pets and Paints
Some pets just cannot resist to eat egg tempera or other paints. Please try to keep your cat or dog away from paints and pigments. Even if the paint is non toxic for humans, some substances may be harmful, especially for cats.
Safety at Work
Please be careful when handling binders and pigments. Do not eat, drink or smoke at work.
Painting materials and food do not belong onto the same table and not into the same refrigerator; solvents should not be used in living rooms. You should neither put a brush in your mouth, nor touch the canvas with greasy fingers. Always wash your hands before eating.
Boiled water and clean utensils help to improve the shelf life of your paints.
Dust formation should be avoided, even with non-toxic pigments. If necessary use a respirator or dust mask.
Particular caution is necessary when using needle-like, fibrous or toxic pigments.
The exposure to large quantities of solvent can cause nausea, headache, and drowsiness.
Hazard identification and safety advice on the product labels are abbreviated. Detailed information, tips on safety, handling and storage for each product can be found in the info sheets and material safety data sheets on our website.