For centuries tempera colours have been used as undercoats for oil and other types of painting. This method is known as mixed medium. Modern acrylic colours are genuine tempera colours, ideally suited for mixed medium techniques used in contemporary art. Acrylic colours are an ideal undercoat for oils. However, painting over newly dried oil paint with acrylic colours should be avoided, since the long drying time of the oil paint may cause small cracks or wrinkles to appear on the surface. Nor should a final coat of varnish be applied until the oil colour is thoroughly dry.

Lascaux Studio, Perlacryl, Aquacryl, Sirius, Gouache and Decora are all well suited for airbrush. Depending on the desired result and final use of the objects, a choice can be made between the permanent acrylic colours Studio and Perlacryl or the watersoluble Aquacryl, Sirius, Gouache and Decora.
The clogging of the nozzle poses the greatest problem for airbrush, no matter which paint is used. During a work break or colour change, the needle and nozzle should always be cleaned immediately (or be put in water). It is very important to keep all the tools  clean when airbrushing. The size of the nozzle depends on the desired effects, but in any case it should not be too small (not smaller than 0,15 mm to 0,5 mm). It is the correct combination of pressure, nozzle size and paint dilution which will provide for the desired results.
It is advisable to mix an ample amount of paint of one hue since remixing is difficult. It is also advisable to sieve the colour (with a fine sieve  available in art supply stores) to avoid any possible particles . Dried paint on the nozzle can be removed by soaking the nozzle in methylated spirit over night and cleaning it with water afterwards.
The colours should be diluted with water until the desired consistency is obtained. This can be made easier by first adding only small amounts of water and stirring thoroughly, then adding more water in increasing amounts. Constant stirring will avoid the formation of lumps. The consistency of the sprayable colours can be adjusted to the size of the nozzle and the air pressure used; the degree of dilution can be between 1:1 and 1:3 paint/water. Strongly diluted colours tend to settle and should therefore be stirred constantly. In place of water, Lascaux Acrylic Transparent Varnish 1 gloss or 2 matt can be used; they prolong the drying time and inhibit the paint from drying on the nozzle.

Preparation and planning of work The success, value, and durability of a painting depend to a considerable extent on good planning. The following prerequisites govern the variable factors which must be carefully considered by the artist. The following are general guidelines for the planning of a painting:

• defining the idea in concrete terms (the artist's ideas or those of his clients)
• determining the quality of the given or chosen support
• checking on need for priming or pretreatement, which depends on the kind of the support and the type of colour to be used
• choosing a suitable colour type and mediums
• choosing a painting technique
• preparing the colour (i.e. diluting, thickening or strengthening by addition of a Lascaux Medium or Acrylic Transparent Varnish and amount of paint needed)
• deciding on a special protective coating for the finished work (varnishing, sealing). In this planning stage there are a number of other factors to be considered, for example: external conditions (weather, local conditions, time allowed for completion), proper tools, containers, installations and accessories. A conscientious artist will bear these in mind when planning his other work so as to avoid unnecessary problems during the actual painting.

The choice of support is not always up to the artist. Regardless whether it is freely chosen or not, the physical properties of the support and the necessity for suitable pretreatment will determine the nature of the painting surface and how it will effect the colours used. It should not be forgotten that a painting is no more durable or stable than the painting's ground and support. The use of acrylic colours with traditional painting methods on the most supports, such as canvas, cardboard, paper and wood, presents few problems thanks to the unique properties of modern artists' colours. If desired, the artist can work directly on these surfaces without special primers, keeping in mind a few basic principles about the application of acrylic colours (open time and retarded drying) and simple painting techniques. In the following section, we will concentrate on mural painting done on concrete and other surfaces found in buildings. These surfaces pose special problems which must be dealt with in a professional manner if the success and durability of the painting is to be ensured.

• The painting surface should always be clean, free of grease and dry. If these conditions are met, any priming coat will adhere without difficulty, particularly acrylic grounds.
• The wall must be firm. Old layers of paint should not crumble or flake when over painted, nor should the surface be prone to peeling or chalking. A priming coat will only stabilize the thin outer surface layer of a support. It will not penetrate any further. Old layers of paint which might chalk or peel can be stabilized to some extent by first applying a penetrating sealer. However this is no longer possible when the surface is already loose and beginning to disintegrate. In such cases, the first step is to reestablish a sound painting surface by removing all the loose material to create an even, stable surface for filling and smoothing with plaster, cement or concrete.
• Layers of old, oily paint and varnish, which make the support too smooth, should first be roughened with a weak ammonium hydroxide solution and, if necessary, treated with a wash primer.
• Metal surfaces must be free of rust and grease. Ferrous metals should be primed with a matt, synthetic resin, antirust coating.
• The support should always be tested for absorbency. Porous or unevenly absorbent surfaces should be sealed with diluted acrylic paint or primer. The basic rule is: the more absorbent the surface, the thinner the first coat should be to ensure proper adhesion.

One of the many outstanding features of Lascaux Acrylic colours is their ease of application. Also, depending on the technique, they can be applied directly on the raw canvas or on a pretreated ground. However, to ensure good adhesion to the painting surface, the above mentioned principle applies again: the greater the absorbency of the support, the more diluted first coat of paint should be. The actual painting support can be prepared by using Lascaux Primer, Uni-Primer, Gesso or ne of the Studio Acrylic White 982 . The primer should be diluted about 25% with water and applied to the previously impregnated or clean surface with a brush or roller. This undercoat can be tinted and a second coat applied depending on the thickness and covering power required. If the prime coat is applied to a support without prior impregnation, it should be diluted at least 1:1 with water. If the artist does not require an evenly coated surface, he can paint directly onto the impregnated support, using highly diluted colour to begin with since they will act as an undercoat.

Most types of textiles are suitable for acrylic painting. They include linen-jute, jute, canvas and also the synthetic fabrics such as polyester, polyamide, polypropylene, fibreglass and monofil fabric. Raw linen , cotton and other natural textiles should be thoroughly washed in warm water prior to stretching on the stretcher. This will remove most of the finishing agent. The fabric may shrink as much as 5 to 10%. For priming, the fabric should be stretched rather tightly onto a stretcher frame. Very absorbent fabric, whether natural or synthetic fibres, should first be sized with Lascaux Acrylic Sizing . If the fabric should loosen , it can be restretched when dry. If so desired, one can paint directly onto the dry sizing. Caution should be taken though that diluted paint does not soak through to the back of the canvas or fabric. For priming, Lascaux Primer or Gesso, diluted with 10 to 25% water, can be used for one or more coats. For colourless priming, Lascaux Medium 2 matt diluted with about 25% water, makes a suitable ground. However, depending on the fabric, the cloth may have to be sized first. Direct painting on unsized and unprimed fabric is also possible with acrylics, especially if the fabric is tightly woven. It should be noted that very diluted colours, when applied to loosely woven fabric, can bleed through to the backside. For direct painting and staining, even with very diluted colours, Lascaux Cotton Duck Canvas No. 10 is ideal: a 470gm2, 250 cm wide, cotton/sail fabric.

Primed Linen and Cotton Duck available through art supply stores, have already been primed with an acrylic or a synthetic resin latex and are generally suitable for acrylic painting. However, one has to be aware of the different qualities available in these ready-made surfaces. The priming is suitable for acrylic painting if it is well bonded and elastic. Primings which are too absorbent, such as traditional chalk gesso, are not recommended for acrylic painting. While oil colours can penetrate such a loosely bound priming, acrylic colours cannot. Acrylics will not adhere well to the chalky surface. Also, oil based primings are not recommended for acrylic painting.

Generally, it is possible to paint directly onto these materials without a priming coat. However, if it is desired, an undercoat of Lascaux Acrylic colours can be used as a priming coat. Depending on the degree of opacity or transparency required, the paint can be diluted accordingly.

With these supports, in order to prevent warping, it is recommended to cover both sides with Lascaux Acrylic Transparent Varnish 1 gloss, diluted 1:2 to 1:4 with water. Special attention should be paid to the possible presence of a wax coating on chipboard, this should be removed with Alcohol or Cellulose thiner before proceeding with the impregnation of the surface . The wood should be thouroughly dry.

Fresh stucco should be thoroughly dry and free of grease. Before impregnating with Lascaux Acrylic Paraloid B 72-10% (solvent-based sealer). To prepare a white or coloured ground use Lascaux Primer or Lascaux Studio Acrylic colours diluted 25% with water.

Pure lime mortar has a long time to set and has a strong tendency to crack. The ground, which should be allowed to dry thoroughly, is then rubbed down with a piece of wood to remove loose sand particles. The next step is to apply a single impregnating coat of Lascaux Hydro-Sealer, diluted 1:4 with water. Then a single priming coat is applied with Lascaux Primer or Studio White 982, each diluted at least 25% with water. In fresco or exterior painting, it is possible to work directly onto the impregnated surface. The first coat of colour should be diluted at least 25% with water.

Fresh fair-faced concrete can be painted over after complete drying. If a wooden form was used, the concrete must be thoroughly cleaned with a brush to remove loose concrete, burrs, wood splinters and traces of formwork oil. Fresh fair-faced concrete must be dry (max. 2-3% remaining humidity) and clean before painting. Concrete with a very smooth surface (especially those cast in plastic or metal formworks) should be cleaned with special care. If necessary, perfectly smooth surfaces should be roughened with a fine sandpaper. Lascaux Hydro-Sealer, diluted with water, should be used for impregnation, subsequently, one or two priming coats should be applied using Lascaux Uni-Primer or Studio White 982, each diluted with at least 25% water. To retain the matt quality and colour of faire-faced concrete, impregnate the surface with a 1:4 dilution of Lascaux Hydro-Sealer and water or apply one coat of Lascaux Medium 2 matt diluted 25% with water. The sealed surface is then suitable for painting with acrylics or gilding with gold leaf.

Use the same procedure as for stucco or fair-faced concrete. Painting on glazed bricks is only suitable for interior walls. If the work will be exposed to the weather, the adhesion strength of the paint will be inadequate.

Use the same procedure as for fair-faced concrete. Priming coats always have to be carried out with Lascaux Uni-Primer, which act as a grip coat for the cement.

If colour is to be applied over a painted surface, the first step is to check the condition of the old coat, particularly the adhesion and absorption. Special care must be taken when painting outdoors. Well preserved old coats should be washed with a solution of water and a small amount of ammonium or household detergent. The new paint should be diluted according to the absorption of the surface. Old coats with poor adhesion should be removed by scraping or with a solvent based remover. Clean the surface well before applying the new paint. Old mineral lime paints should first be checked for chalking and absorption. Chalking coats should be washed as above. Depending on the absorption of the support after cleaning, it should be treated with solvent based Lascaux Paraloid B 72-10%. This should be diluted so that when dry, the priming coat does not have a glossy appearance.

Synthetic resin bound renderings should be checked in advance for absorbency. The painting surface can then be primed following the guidelines for new or painted plaster work.

These non-absorbent supports must first be cleaned and degreased, for example with methylated spirit. They should then be lightly sanded and, in certain cases, given a coat of Lascaux Uni-Primer to form a strong white ground. When a transparent ground is required, use Medium 1 gloss. For best results Lascaux Acrylic colours should be mixed in a 1:1 to 2:1 ratio with Lascaux Medium 1 gloss or Transparent Varnish 1 gloss. This will improve their adhesive strength. On all non- absorbent supports, the adhesion of this mixture is adequate but not sufficient to withstand mechanical stress. The adhesion of glas is thus problematic. However Lascaux Acrylic colours are particularly suitable for behind glass painting. Their quick drying properties allow for rapid working. The surface requires careful cleaning and degreasing. These applications should only be done for interior works.

After thorough cleaning and removal of grease, non-ferrous metals such as aluminium, brass, copper, along with zinc and galvanised iron, can be painted directly with Lascaux Acrylic colours. To obtain greater hardness of paint film and even better adhesion, Lascaux Transparent Varnish 1 gloss can be added to the acrylic colours. For an excellent white priming and crip coat over the metal, Lascaux Uni-Primer is highly recommended.

Natural stone should first be checked for absorption and any signs of crumbling. If loose particles are detected, the stone should be wirebrushed and the surface impregnated with Lascaux Hydro-Sealer, diluted 1:4 with water. Highly absorbent stone should be impregnated in the same way. With natural stone it is often advisable to apply a bonding coat using Lascaux Acrylic Transparent Varnish 1 gloss, diluted 1:4 with water. The stone can then be painted with Lascaux Acrylic colours. To obtain a particularly hard paint film, the acrylic colours can be mixed 1:1 to 2:1 with Lascaux Acrylic Transparent Varnish 1 gloss. For a white base coat, Lascaux Uni-Primer should be used.

In the section on painting aids, reference has already been made to the various kinds of finishing coats which can be applied. We also mentioned that Lascaux Artist, Studio, Bronze and Perlacryl colours are reasonably water and weatherproof after drying. However, it is always advisable to enhance the durability of a work and protect it from possible damage by varnishing. Works in acrylic colours are better protected against damage caused by exposure to weather, (especially UV radiation), by dirt and atmospheric influences, by the resulting efflorescence of the support, or by mechanical stress if they are properly sealed. The simplest form of protective coat is provided by Lascaux Acrylic Transparent Varnish (for exterior work Lascaux Acrylic Transparent Varnish-UV). Lascaux Mediums can be used for interior work and canvases. Painted objects in everyday use, such as toys, furniture, etc., should be sealed to protect them from damage and wear caused by frequent handling. The most suitable product for this purpose is again Lascaux Acrylic Transparent Varnish. Paintings which are not waterproof or scratch resistant can be protected against wear and damage by fixing with Lascaux Fixativ. If a work should be damaged in any way, please consult us prior to repairing the work. We will be able to make recommendations for techniques and products which can be used depending on your particular problem.

Once dry, Lascaux Acrylic colours are insoluble in water, but can always swell in alcohol. It is often difficult to remove paint spots from clothing, since all pigments have a special preference for textile fibres. Sometimes acrylic colours can be removed from clothing with liquid detergent applied directly with a compress , this dissolves the colour very gently, preventing the formation of large spots. Brushes with dried-in colour should be cleaned with Lascaux Brush Cleaner.