Derivan / Techniques / Surface preparation Techniques

SURFACE preparation techniques

Paper, Board, & Cardboard

Paper

As a general rule, Derivan Acrylics may be applied directly over paper, board and cardboard without priming the surface. It is advisable to use a good quality paper or board though, as Derivan Colours are made to last and they will help to protect the paper they cover: no paint will turn a poor quality paper into a good one.

Just about any paper may be used; however, paper lighter than 300gsm will probably need to be fixed down to avoid curling (see watercolour techniques with acrylics).

If the artist does not want the paint penetrating very thin paper, apply two very thin coats of Derivan Polymer Gloss Varnish mixed equal parts with water. This will bind well with the surface of the paper and act as a sealer without penetrating the paper. Derivan Colours are formulated to last, whilst most papers have a rather more finite life. Priming the surface of paper with the Derivan Polymer Gloss Varnish will provide the way for restorers to remove the paper once it has deteriorated and replace it with a fresh substrate.

If a primed surface on paper is desired, the best surface can be achieved by applying one coat of Derivan Gesso mixed equal parts with water. The absorption rate of the paper and the desired painting surface will dictate how much dilution with water the Gesso requires and how many coats thereafter. It is best not to build the surface too high with Gesso (i.e. 5-6mm is getting too thick) to avoid cracking. If a thick surface is required, use Impasto Medium to achieve high relief.

Canvas/Linen

Derivan Colours can be readily applied to the vast majority of fabric supports. These include cotton, linen, jute, canvas, polyester, polypropylene and fibreglass fabrics.

Cotton and other natural fibre supports, although widely used, have the inherent problem of their reaction to climate. This can affect them in several ways. Natural fibres tend to absorb moisture from the air; this can cause swelling in the fibres. Constant swelling and contraction, potentially causing premature cracking, will not be as detrimental to acrylics, because of their elasticity, as may be the case with oils. However, the constant expansion and contraction may eventually destroy the canvas itself. The absorption of moisture may also promote bacterial growth. From a long-term point of view, synthetic canvases do not exhibit the same moisture absorption characteristics and are much more resistant to bacterial or fungal growth.

Canvas/Linen Stretched

This refers to canvases that have been stretched over a support, usually a wooden frame made from specially produced stretcher bars. These stretcher bars have the side parallel to the canvas tapered down so that only the outside edge touches the canvas. This avoids the inside edge of the stretcher bar touching the canvas and revealing the shape of the stretcher frame against the canvas.

Unprimed/Raw Canvas

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When a non-synthetic canvas is primed, it will shrink. The amount of shrinkage will depend on the type and weight of the canvas. Using Derivan Gesso diluted with equal parts water, the first and second coat will penetrate the raw canvas and bind well. Ensuing coats may contain 50% or less of water, dependent on how absorbent the canvas is and the particular surface required by the artist. The Gesso may be sanded and recoated to give a very flat finish almost hiding the weave of the canvas (e.g. for use with airbrushing).

If a preference for working directly onto the raw canvas is desired, Derivan Artist Acrylics can be used straight onto the surface. However, it is advisable to seal the canvas first with Clear Sealer or Polymer Gloss Varnish or Polymer Matt Varnish. Sealing the raw canvas will increase its longevity. As canvas is quite porous, it tends to mark and stain quite easily; sealing will decrease this tendency. Sealing will help to protect cotton and linen canvas from mould and bacteria. It will also prevent the paint staining through the canvas to the other side when using the paint in a thin liquid form.

Pre-Primed Canvas

It is prudent to be sure of all substrates an artist is to employ. Even the most reputable brands sometimes appear to focus more on the quality of linen and frame and use a primer that may not always stand up to the conditions that are required of them.

If the artist wishes to be sure of the ground they are to work on, lightly sand back the pre-primed surface (do not sand back all the way to the canvas). Apply one coat of Derivan Gesso mixed equal parts with water. The next coat can be straight Gesso or may be diluted depending on the required surface.

Concrete

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Rough concrete should be cleaned and free of dirt, dust, grease or oil. Ensure all loose sand, formwork particles etc. have been removed. Apply a coat of Derivan Gesso. This may be diluted if required. If the concrete is new, it would be prudent to apply a coat of Derivan Clear Sealer before the Derivan Gesso to block any potential leaching of alkaline residue. Alkaline residue has the potential to affect some acrylic colours if leached in high enough concentrations.

Clean-faced or polished concrete may need to be sandblasted to give a surface for a primer to adhere to. Following sandblasting, clean the surface of dust and loose material and apply a coat of MM10 Gesso. If the surface still feels very smooth, it would be advisable to lay down a coat of the Derivan Polymer Gloss Varnish & Gloss Medium before applying the Gesso.

Fibreglass

Surfaces which are non-porous can present a problem if they are to be employed as a substrate for a work which may have to stand up to abrasive or mechanical stress and/or the elements over a long period. The more substantial a foundation that can be laid for the paint, the longer it will last. Always test the substrate before commencing work if you are in any doubt about its suitability.

The surface of the fibreglass should be lightly scratched with sandpaper or a wire brush then cleaned down so it is free of any oil, grease or dust. A bonding coat of Derivan Polymer Gloss Varnish should be applied, then a coat of Derivan Gesso. Leave this to dry for 48hrs and test adhesion by attempting to scratch the surface. A good test is to cut an "X" about 2cm long into the primer, stick a piece of masking tape over this and pull it off. If the paint comes with it, it is not going to be a long-lasting foundation. After the work is complete, a further one or two coats of the MM7 Polymer Gloss Varnish is recommended to protect it. If the work is to be exposed to sun and rain, a further coat of MM14 Final Varnish Gloss Finish would be recommended.

Plasterboard

It is possible to apply Derivan Colours directly to plasterboard that has been cleaned of all dust, oil and grease. Gesso may be used as a primer, if desired, as it will give good tooth and a clean bright surface to work on. If the plasterboard appears to be extremely porous, the use of MM10 Gesso as a primer is recommended. After the work is complete, a coat of Derivan Polymer Gloss Varnish is recommended to protect the work. If the work is to be exposed to sun and rain, a further coat of MM14 Final Varnish Gloss Finish is recommended.

Plaster/Stucco

New plaster should be left to dry for at least 2 weeks before a coat of Derivan Clear Sealer is applied. Derivan Gesso may then be used or Matisse Colours applied directly over the MM12 Clear Sealer. After the work is complete, a coat of Derivan Polymer Gloss Varnish is recommended to protect the work. If the work is to be exposed to sun and rain, a further coat of MM14 Final Varnish Gloss Finish is recommended.

Glass/Ceramic Tiles

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It is possible to use Derivan Colours on glass or tiles for a permanent, although not dishwasherproof, finish. First, apply a coat of undiluted Derivan Polymer Gloss Varnish. Next, apply the paint as desired. Finally, finish off with another coat of MM7 Polymer Gloss Varnish.

If a transparent finish is required, dilute the Matisse Colours with the Polymer Gloss Varnish instead of water. This will give more permanence to the work.

If a finish such as frosted glass is required, use Gel Medium directly onto the glass. See section on Gel Medium.

Although the above instructions will give a very long lasting finish on decorative items and windows, this process is not recommended for everyday utility items, such as glasses or plates. To date, it is not possible to find a water-based product which will adhere to glass and ceramic tiles as well as those glazes which are fired.

Wood

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It is possible to apply Derivan Acrylic Colours directly to wood that has been cleaned of all dust, oil and grease. If the wood appears to be unduly sappy or green, use of Derivan Clear Sealer is recommended as a tannin blocker and sealer. Derivan Gesso may be used as a primer, if desired, as it will give good tooth and a clean bright surface to work on. If using Matisse Background Colours, a sealer is not necessary, except on the greenest of woods, as they have a built-in sealer. A coat of Polymer Gloss Varnish or Polymer Matt Varnish is recommended as a finish coat, to protect the completed work. If the work is to be exposed to sun or rain or the item is a utility item which may require a hard and heat-resistant finish, a coat of MM11 Satin Varnish or MM19 Poly-U-Gloss Varnish is recommended.

Chipboard & MDF

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Gesso may be used as a primer, if desired, as it will give good tooth and a clean bright surface to work on. If using Matisse Background Colours, a sealer is not necessary except on the most porous of chipboards as these colours have a built-in sealer. After the work is complete, a coat of Polymer Gloss Varnish or Polymer Matt Varnish is recommended to protect the work. If the work is to be exposed to sun or rain or the item is a utility item which may require a hard and heat- resistant finish, a coat of MM11 Satin Varnish or MM19 Poly-U-Gloss Varnish would be recommended.

If you find that after applying your first coat of Matisse Background Colours, the routed edges are still furry, apply a single coat of MM26 Transparent Gesso (pastel primer) over the area requiring attention, sand and then recoat with desired background colour. Although not originally designed for this purpose, many folk artists now use MM26 Transparent Gesso (pastel primer) as their preferred preparation on craftwood routed edges.

If chipboard or MDF is to be exposed to rain, it is recommended that all sides of the board be covered with paint and then the varnish to stop the board soaking up water, warping and disintegrating. Although the Matisse range of products when applied correctly will prolong the life of particle boards, alternative substrates should be sought if the work is to stand up to the elements over an extended period.

Fabric

In general, Matisse Colours can be used directly on most fabrics. If the fabric is to be washed regularly (for example clothing) or exposed to the elements, Derivan Fabric Fixative would be recommended.

Metal

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Non-ferrous metals such as copper, aluminium, brass, zinc (galvanised iron and tin) can be roughened up using sandpaper or a wire brush, cleaned of all oxidation, grease and oil, then painted with Matisse Colours. An undercoat of Polymer Gloss Varnish can be applied first for added adhesion.

Ferrous metals such as iron, cast iron, steel and tin, should be sandblasted or wire brushed to clean metal, removing all oxidisation and scaling. At this point, many artists have found a coat of Polymer Gloss Varnish as an undercoat has worked well. If the item is to be exposed to a very salty or humid atmosphere, then a metal primer with a suitable rust inhibitor that is compatible with water-based paints, would be recommended in place of the Polymer Gloss Varnish.

Plastics & Melamines

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Matisse Colours will adhere directly onto most plastics. Non-porous materials such as perspex, melamine or nylon should be lightly sanded then a bonding coat applied of undiluted Polymer Gloss Varnish or Clear Sealer. Paint as desired and finish off with another coat of Polymer Gloss Varnish.

N.B. Non-porous plastics will accept the paint. However, painting hard-wearing plastic or melamine objects (such as kitchen bench tops) should be avoided.

Fibre Cement Board

It is possible to apply Matisse Colours directly to fibre cement board that has been cleaned of all dust, oil and grease. Gesso may be used as a primer, if desired, as it will give good tooth and a clean bright surface to work on. If using Matisse Background Colours, a sealer is not necessary, except on the most porous of boards, as they have a built-in sealer. If the fibre cement board appears to be extremely porous, the use of Gesso as a primer is recommended. Use a coat of Polymer Gloss Varnish to protect the finished work. If the work is to be exposed to sun and rain, a further coat of MM14 Final Varnish Gloss Finish is recommended.

Stone

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The stone should be cleaned of all oil, grease and loose dust and sand. Some types of stone are unsuitable for painting as they will tend to flake and fall apart. In general, most natural stones should be sealed with Clear Sealer or Polymer Gloss Varnish or Polymer Matt Varnish. Matisse Colours can now be used directly over the Sealer or MM10 Gesso may be used as a ground, if preferred. If the painted stone is to be left out in the elements, two coats of MM15 Final Varnish Matt Finish or MM14 Final Varnish Gloss Finish is recommended.