Cracked or crackled paint finishes are achieved by producing cracks in a layer of paint, thus exposing a second layer underneath.

(although Matisse products are mentioned below, these techniques should be applicable to similar products in other brands.

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Introduction

• Craquelure is the term used for the finish resulting in hairline cracks in a varnish.
The cracks do not open up and reveal the surface underneath, but is rather like the cracks in the glaze of an old porcelain plate.

• Cracked paint finishes and Craquelure are two different finishes. Crackle or the effect of cracked paint will be described below. As yet a true craquelure finish is not consistently obtainable with water-based paints.

• Paint-makers since time in memorial have been constantly formulating and re-formulating so as to make their paints last longer and longer and most certainly to avoid cracking. Therefore when the paint is required to crack it is working against what it has been designed to do. As with anything that is working on the limits of its specifications there are some guidelines that must be followed to ensure the desired results.

Procedure

• Step 1. The first coat of paint laid down will be the colour that shows through as the cracks. This first coat should be a water-based paint such as Matisse Professional Artist Acrylics Flow or structure formula or for larger areas Matisse Background Colour will give the best results. Leave this coat to dry before going to step 2.
It is possible to omit this coat. If the desired effect is to show the surface as cracks, the cracking medium can be applied directly to any surface that acrylic paints will normally adhere too. For example if cracking on a wood surface and the desired effect is to have the paint cracking to reveal the woodgrain underneath, skip this step 1 and start at step 2 ensuring the surface is clean and free of oil, grease and dust.

• Step 2. Once step 1 is dry apply Matisse Medium MM 21 Cracking Medium or Matisse Medium MM 23 Cracking Medium (water-based).
The cracking medium may be applied with a brush, sponge applicator, roller (either a sponge or short nap roller). Apply the cracking medium so that it is as thick as possible but not so thick that it runs when the surface is held vertically. The cracking medium is designed to be a high build coat therefore is very viscous (thick). Do not be overly concerned with obtaining an even flat surface as the cracking medium has a built in flow agent, which will allow it to level out as it dries.

• Step 3. This is the coat that cracks to reveal the coat applied in Step 1. Step 3 must be applied within 12 hours of the step 2 drying. The paint used MUST be Matisse Background Colour as the Cracking Medium has been especially formulated to work with this paint.
The special formulation unlike some other brands allows for different types of cracks to be achieved and repeated with consistency.

• The Matisse Professional Artist Acrylics Flow and Structure ranges will not always work as a topcoat with the Cracking Medium unless they are mixed with Matisse Medium MM 5 Matt Medium (this is discussed further in Cracking Metallic and tube colours).

• When applying the topcoat it is important not to re-work areas that have already been covered as re-working an area can lift the cracking coat and stop the process (see below for more details).

How it Works

• The old methods of cracking using gum arabic and forced drying were quite unreliable. They relied on the different drying speeds to crack the paint. The climate had to be just right and the slightest mistake would result in the process not working.The cracking process relies on a reaction between the topcoat of background colour and the cracking medium, which has been applied below it. Once the topcoat is applied the cracking coat below becomes semi-liquid again and shrinks, taking with it the topcoat.

• It is worth noting that the topcoat should be applied systematically covering the surface and not going back over an area that has already been covered. As described before the paints have been designed not to crack, therefore when the cracking medium is trying to shrink and take the topcoat with it, the topcoat is actually trying not to break apart.

• The thickness of the topcoat, will dictate how big the cracks are. The thicker the top coat the more easily it is able to hold together and resist cracking but when the cracking medium  gets its way and manages to crack the top coat it will result in a very large crack. Thus the thicker the topcoat of background colour the fewer the cracks but they will be big ones.

• Conversely if the topcoat is applied very thinly the cracking medium will strike less resistance from it and therefore result in many more cracks but they will be much smaller in size.

How to Achieve Different Patterns

• Following on from above it can be seen that if the topcoat were to be applied using a brush and brushing in the one direction, the overall pattern of cracks would be in the direction of the brushstrokes. This is because even though one aims, when using a brush to lay down a nice flat coat, in reality if the brush stroke is studied closely the topography of the paint has corrugations in it. These corrugations run parallel to the drag of the brush. As described above the paint will tend to crack at its least point of resistance or where the paint is the thinnest. Therefore the thinnest parts in a brushstroke are the troughs in the corrugations. Which in turn give the elongated cracking pattern.

• If a sea sponge were employed to apply the topcoat the topography would be more akin to sand dunes therefore the resultant pattern would be more rounded and random.

Other influences on patterns

• The types of cracks obtained depend on the thickness of the topcoat and the way in which it is applied. The bottom coat has no bearing on the outcome of the cracking pattern. The way in which the cracking coat is applied will not effect the pattern, unless it is to thin in which case it just won't work.

• The surface on which the finish is to be applied may have some bearing on the pattern. For instance if very large cracks are desired the topcoat will need to be applied very thickly. It will be necessary to have the surface horizontal as the weight of the paint may run and pull the cracking medium if the surface is vertical.

• On frame mouldings or 3 dimensional pieces the paint, as it cracks will tend to sink due to gravity, to the lower surface. This may leave edges or sharp points exposed and make the piece look contrived.

If the artist is new to this finish it would be prudent to do some tests on an old sheet of cardboard etc. before a large project is attempted.

Finishing off

• It is not necessary to varnish the cracking finish unless it is to be used on utility items with a lot of wear and tear or if it is to reside outdoors. The cracking medium may also give a higher sheen to the first coat (i.e. the cracks) than the topcoat.

• A varnish may be used to even out the different sheen levels as well as protecting the finish from water and some wear and tear. Use only a solvent based varnish such as Matisse Medium MM 14 Final Varnish: Gloss Finish or MM 15 Final Varnish Matt Finish.

• DO NOT use a water based varnish as a final coat as it may crack.

Cracking Metallic and Tube Colours

• As previously mentioned the Matisse Cracking Mediums are designed to work only with the Matisse Background Colours. However it is possible to use Matisse Professional Artist Acrylics in the Flow or Structure Formula as a topcoat.

• To use the Structure or Flow, which includes the Metallic colours of golds, silver, copper and bronze. Mix the colour equal parts with Matisse Medium MM 5 Matt Medium. This mixture may then be applied over the cracking medium in the way described above. The Matt Medium gives the correct ingredients needed to activate the cracking medium while reducing the amount of binder in the paint allowing the cracking medium to work.

Cracking Varnish

• An interesting effect over a painted piece or even a print is that of cracked antiquing. It is possible to crack a water-based varnish.

• Omit step 1 and start at step 2 as described above, applying the cracking medium over the piece or print.

• Step 3 as a topcoat: Use one of the following Matisse Medium MM 6 Polymer Matt Varnish water based, MM 7 Polymer Gloss Varnish & Gloss Medium, MM 11 Satin Varnish, MM19 Poly U Gloss Varnish. Apply the varnish as a topcoat as per the directions above to obtain the desired types of crack. The result will be a clear varnish with cracks in it. As the varnish is clear and the cracking medium is clear the cracks will be hard to see, so the next step is to antique the piece so that the cracking stands out. Leave the piece for at least 48hours after it has finished cracking as the antiquing process can re-start the cracking if it is not fully dry.

• Step 4: Using a rag soaked in Matisse Medium MM 20 Water Based Patina Antiquing Medium add a little dab of Matisse Flow Formula Raw Umber and wipe this over the surface. The raw umber should catch in the cracks and "dirty" the piece up giving a time worn look.

Faux Antique Gilding

One way of producing a beautiful old cracked gilded frame is to gild a frame and wait 200 years. Another, much quicker way is to imitate the finish. This is done via a series of steps set out below.

• Step 1: Basecoat the project with Matisse Background Colour (the colours most often used are china red, burgundy and pale beige.)

• Step 2: As above apply the cracking medium and leave to dry.

• Step 3: As described above mix Matisse Flow Metallic Light Gold with Matisse Medium MM 5 Matt Medium equal parts and apply with a sea sponge or brush by dabbing in a perpendicular motion to the surface. Leave to dry for 48 hours.

• Step 4 Antique the project as per step 4 above.

Presto one antique faux gilded frame! With a little practice it is possible to achieve a finish that is uncannily close to the real thing. For instance keep in mind that gold leaf is usually applied in sheets of 5 to 10 cm so every 5 or 10 cm if the gold is applied a little thicker it will resemble the overlapping of the sheets. (courtesy of Matisse Derivan)
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