MDF Painting Specification
MDF (Medium Density Fibreboard) is used extensively for trim work such as architraves, skirting board. plain and panelled doors.
It can be supplied either untreated or with a factory applied priming coat.
If the priming coating is in sound condition can be overcoated with oil or water based undercoats and finishing coats.
Any damaged or raw areas should be re-primed using an oil based primer.
Painting system.
New MDF.
Remove by the most appropriate means all surface contamination. Lightly abrade the surface with medium grit 120 grade. Dust off and wipe clean with damp cloth and leave to dry.
Raw edges should be filled with suitable wood filler or a thin coat of a ready mixed fine plaster filler or drywall compound both of which are easy to sand down to give a smooth finish. After sanding and removing all surface dust, apply one coat of primer and recommended number of finishing coats in accordance with the selected manufacture's product information data sheets.
Note; Not all water based primers are suitable for MDF as they may cause the wood fibres to swell which would then be difficult to rub down to a smooth surface. Therefore check the manufactures recommendations before use.
PPE. As the composition of MDF is made from fine wood fires when sanding or cutting it is essential that a suitable face mask and eye goggles are worn,
Marbling Toolbox
Basic Toolbox for Marbling
For further information on tools and materials:
http://www.handover.co.uk Tel: 020 7241 5877
Marbling Traditional Techniques
Marbling Traditional Techniques
General
Environment.
Cleanliness and unrestricted work area is most important to create, as far as possible, a dust free environment.
Surface preparation.
Ensure all loose defective material is removed back to a firm edge. Fill all surface imperfections with a suitable filler/surfacer followed by thoroughly sanding/rubbing down to a smooth sound finish.
One or two coats of an oil based ground coat, colour to suit and when dry lightly abraded with 1000 grade wet or dry to remove any surface nibs, rinsed with clean water and allowed to dry.
Apply selected scumble in accordance with the manufactures recommendations.
Note: All wet materials should be strained before us to remove any contaminants before use and all surfaces should be tack raged to remove any surface dust.
Basic steps for Marbling involves:
Onto the prepared surface take a quantity of scumble and add the appropriate stainers required, and brush apply to the surface in an uneven pattern scrubbing the coating out. Using a clean cloth or sponge dab onto the surface.
Repeat with a mixture of the next selected colour by applying the material in different areas in an uneven pattern followed by the softening process. Repeat as required. If thin vein lines are within the pattern either fine pencil brushes or the edge of a swan's feather dipped into the colour and applied at various thickness using the feathers edge, and repeat the softening process.
Full range of tools and material available from: https://www.handover.co.uk
Training centres for advanced Decorative finishes are available throughout the UK including:
https://www.southcoaststudio.co.uk
https://www.schoolofdecorativeart.co.uk/marbling
Health and Safety
As solvents and rag are used it is important that all used rag/clothes are fully opened after use to allow the solvents to evaporate. Not doing this could lead to the combustion and a fire.
Graining Techniques System
Selection of Different Wood Types
Light Oak.
White base with added Ochre. A little of raw umber is occasionally added.
Ready mixed ground coat colour NCS colour range 0030G90Y
Dark Oak.
Yellow ochre, Venetian red and burnt umber added to a white base.
Ready mixed ground coat colour NCS colour range 2010Y30R
Medium Oak.
White base with added Ochre and slightly more raw umber than used for light oak.
Ready mixed ground coat colour NCS colour range 0030G90Y
Walnut.
French Ochre, Venetian red to a white base.
Ready mixed ground coat from NCS colour range 3030Y70R
Pitch pine.
French ochre, Venetian red added to white.
Ready mixed ground coat colour NCS colour range 0030G90Y
Brush Graining. Health and Safety. Environment.
Cleanliness and unrestricted work area is most important to create as far as possible a dust free environment.
As solvents and rag are used it is important that all used rag/cloths are spread out flat after use to allow the solvents to evaporate. Not doing this could lead to combustion and fire.
Surface preparation
Ensure all loose defective material is removed back to a firm edge. Fill all surface imperfections with a suitable wood filler/surfacer and then thoroughly rub down with suitable abrasive paper preferably wet to leave a smooth, sound finish.
One or two coats of an oil based ground coat in the appropriate colour should be applied and when dry sanded down with 1000 grade wet or dry to remove any surface nibs, rinsed with clean water and allowed to dry.
Apply selected scumble in accordance with the manufactures recommendations and after completing the required grain design and when dry apply one coat of selected clear satin varnish.
Note: All wet material should be strained before use to remove any contaminates and before use all surfaces should be tack ragged down to remove any surface dust.
For further information on how to grain see: Graining Toolbox.
Spraying Conventional Air Spray
;
A conventional air spray unit operates byway of a remote compressor and a pressure pot the size of which can be between 5 and 15 litres.
As the operating atomising pressure is set to 2-3 Bar (1 bar =14psi) this causes considerable over spray dust. Therefore extensive masking up and ventilation is necessary.
In cases where small work is required then in place of a pressure pot a spray gun with either a gravity or suction fed pot is attached to the spray gun.
Spray painting setup.
Before commencing always read the manufacture's instructions for use and health and safety data sheets for both the equipment and paint products.
Ensure the work area is clear and free from obstacles, all preparation has been completed and areas not being sprayed are fully protected.
For air assisted spraying the type of compressor used is generally electric. However, note that on building/construction sites a 110 volt unit is required.
Procedure:
Connect the air line from the compressor onto the pressure pot and the air and fluid lines from the pressure pot onto the spray gun.
Place the mixed paint into the pressure pot and switch the compressor on and make sure that both the the air and paint fluid lines to the spray gun are also connected and open. Check the air pressure within the pressure pot is in accordance with the product data sheet. The air supply valve on the spray gun should be turned off. Aim the spray gun into an empty container, pull the spray gun trigger back and the paint should then uniformly flow out of the gun. Once satisfied that the flow is correct slowly open up the air line until the spray fan is as required for the work being carried out.
Spray equipment available from companies and merchants such as:
https://www.brewers.co.uk/search?q=spray+units
https://www.brewers.co.uk/stores
https://www./wagner-group.com/uk/contractor
Sales and servicing:
http://www.tradepaintservices.co.uk/contact
Decorative Textured Finishes
Preparation.
General.
New plasterboard.
Ensure all surfaces are are clean, dry and free from flaking/defective material, oil and grease.
For previously oil painted gloss surfaces, lightly abrade to provide a key, wash down using a damp sponge remove loose contaminates and allow to dry.
Any surfaces which are powdery in nature apply one coat of stabilising solution applied in accordance with manufactures instructions. Note : When dry any areas which display a gloss finish should be lightly abraded before progressing.
Surfaces of high porosity apply one coat of General Purpose Sealer in accordance with manufactures instructions.
Textured Base coats and Finishes should be mixed and applied in accordance with manufactures instructions.
For further information and product advice: https://www.artexltd.com
Decorative Textured Finishes (Artex®)
Toolbox for Decorative textured finishes.
Notes: Artex® is a registered brand name and is generally referred to within the building and decorating trade to describe textured finishes.
For further information : https://www.artexltd.com/about-artex
Check manufacturer's advice on any Personal Protective Equipment needed.
Wet wood Rot
Wet Wood Rot
Cause
A moisture content in wood in the region of 40% + is the point when the timber fibres begin to degrade. The major cause is poor maintenance, allowing moisture to enter the wood when exposed to the elements or for example, internally, where the sealant/putty seal between the glass and window frame has failed and condensation occurs, the water is then absorbed into the wood, affecting the cross rails, cill and styles.
Timber affected by Wet Rot will feel soft and spongy (even through a coat of paint) and look darker than surrounding timber. When dry, the timber will easily crack and crumble into fine particles. It can also be susceptible to shrinkage.
Some types of Wet Rot cause the wood to bleach. This is common in doors and window frames.
If the paint film is damaged and not treated this can increase the risk of wet rot. If you suspect wet rot and the paint film is not damaged, push a thin bladed knife into the painted timber. The blade should stop after a short distance. If it goes in up to the handle, it is almost certainly a sign of rot behind the paint coatings.
Remedy
Wet Rot is easier to deal with than Dry Rot, as the cause is restricted to where moisture has entered the wood. Depending on the degree of Wet Rot, it may be necessary to remove and replace a section or the item, e.g. window/door. Where the defect is restricted to one area then it may be possible for a qualified joiner to cut it out and replace with new wood. Alternatively, a special two component wood repair system can be used by following the manufacturer’s instructions. Painting can then be carried out in accordance with the proposed specification.
For further information and specific advice contact: www.repair-care.co.uk windowcaresystemsang (Video)
Spraying HVLP (high volume low pressure)
HVLP (high volume low pressure). The advantage of HVLP spray units is that they operate on a lower pressure, therefore, can be used within a domestic area as little overspray is created.
Ideal for spraying decorative paints and in particular multi-colour finishes.
As overspray is minimal, the use of this type of spray unit is very cost effective as the time spent on masking and sheeting is reduced.
Spray equipment available from companies such as: Wagner-group Ltd.
https://www.wagner-group.com/uk/contractor/products-and-accessories/product/finecoat-9900-plus/