Hardboard
Hardboard is a compressed, composite board. Fibre residuals are saturated in a wet process and then compressed to a sheet. A fine fibre overlay is applied (normally to one side) to provide smooth face.
Three basic types are available - standard, medium and oil-tempered. A number of specially finished boards are available for specific purposes.
• Standard With a smooth surface on one side and a mesh texture on the other, this can be used for wall and ceiling panelling, floors, door panels, built-in cupboards and fitments etc.
• Medium This is less dense than standard hardboard but it is thicker and so more rigid. There are two types: LM (low density) which will take drawing pins and can be used for pin boards and notice boards, and HM (high density) which is suitable for wall and ceiling lining, partitions.
• Tempered Treated This is usually treated with oil to give extra strength and water resistance, it is particularly suitable for exterior use.
As well as being supplied in flat sheet form, hardboard is also available with various designs of perforations (to act as peg board or decorative grills) and with 3D decorative designs on one face (usually ridges or similar repeat patterns).
Working with hardboard
When handling hardboard, take care not to damage the surface of the finish face. If a full sheet twists it can tear across the whole width.
Conditioning
To prevent sheets buckling due to a change in moisture content, manufacturers recommend they should be conditioned before use. There are two ways of doing this.
• For standard and LM (low density) type medium and tempered boards, scrub the backs with water, using I litre to every 2440 x 1220mm sheet. Then stack the sheets flat, back to back, for 24-48 hours (48-72 hours for tempered boards).
• For HM (high-density) type, medium boards and all boards to be used in centrally heated surroundings, stack the sheets on edge in the room where they are to be used, separating them with wood off cuts to allow the air to circulate. Leave HM medium boards for 48 hours and other boards for 72 hours before using them.
Use a fine tooth saw and cut into the face of the board, supporting it on both sides of the cutting line. Pre-decorated and plastic-covered boards should first be scored along the cutting line using a sharp knife and straightedge to prevent the edges chipping.
Fixing
Hardboard may be fixed by screws, hardboard pins, nails or adhesives; follow the manufacturer's recommendations relating to the particular type of board and its use. The heads of hardboard pins are designed so that they 'disappear' into the surface after they have been hammered home.
You can use general purpose impact adhesive (for instant fixing) and woodworking PVA or synthetic resin-based ones - where possible, pin or cramp the work piece while the glue is setting. Generally the glue only bonds to the top surface of hardboard and if a joint fails, it is generally not the glue but the top surface of the board which separates from the underlying board.
Finishes
Knocks to the edge of hardboard will cause damage, so fit a thin strip of softwood along the finished edge or put a rebate in the support frame so that the hardboard can be recessed.
Hardboard which is not already primed should be treated with special hardboard primer/ sealer before being painted or papered. Diluted emulsion paint (one part of water to four of paint) or aluminium paint may be used as a primer unless the surface is to be papered. Wood primer should not be used.
Hardboard is normally available in 2440 x 1220 sheets (or subdivisions) and in thicknesses from 2.4 to 13 mm.
Three basic types are available - standard, medium and oil-tempered. A number of specially finished boards are available for specific purposes.
• Standard With a smooth surface on one side and a mesh texture on the other, this can be used for wall and ceiling panelling, floors, door panels, built-in cupboards and fitments etc.
• Medium This is less dense than standard hardboard but it is thicker and so more rigid. There are two types: LM (low density) which will take drawing pins and can be used for pin boards and notice boards, and HM (high density) which is suitable for wall and ceiling lining, partitions.
• Tempered Treated This is usually treated with oil to give extra strength and water resistance, it is particularly suitable for exterior use.
As well as being supplied in flat sheet form, hardboard is also available with various designs of perforations (to act as peg board or decorative grills) and with 3D decorative designs on one face (usually ridges or similar repeat patterns).
Working with hardboard
When handling hardboard, take care not to damage the surface of the finish face. If a full sheet twists it can tear across the whole width.
Conditioning
To prevent sheets buckling due to a change in moisture content, manufacturers recommend they should be conditioned before use. There are two ways of doing this.
• For standard and LM (low density) type medium and tempered boards, scrub the backs with water, using I litre to every 2440 x 1220mm sheet. Then stack the sheets flat, back to back, for 24-48 hours (48-72 hours for tempered boards).
• For HM (high-density) type, medium boards and all boards to be used in centrally heated surroundings, stack the sheets on edge in the room where they are to be used, separating them with wood off cuts to allow the air to circulate. Leave HM medium boards for 48 hours and other boards for 72 hours before using them.
Use a fine tooth saw and cut into the face of the board, supporting it on both sides of the cutting line. Pre-decorated and plastic-covered boards should first be scored along the cutting line using a sharp knife and straightedge to prevent the edges chipping.
Fixing
Hardboard may be fixed by screws, hardboard pins, nails or adhesives; follow the manufacturer's recommendations relating to the particular type of board and its use. The heads of hardboard pins are designed so that they 'disappear' into the surface after they have been hammered home.
You can use general purpose impact adhesive (for instant fixing) and woodworking PVA or synthetic resin-based ones - where possible, pin or cramp the work piece while the glue is setting. Generally the glue only bonds to the top surface of hardboard and if a joint fails, it is generally not the glue but the top surface of the board which separates from the underlying board.
Finishes
Knocks to the edge of hardboard will cause damage, so fit a thin strip of softwood along the finished edge or put a rebate in the support frame so that the hardboard can be recessed.
Hardboard which is not already primed should be treated with special hardboard primer/ sealer before being painted or papered. Diluted emulsion paint (one part of water to four of paint) or aluminium paint may be used as a primer unless the surface is to be papered. Wood primer should not be used.
Hardboard is normally available in 2440 x 1220 sheets (or subdivisions) and in thicknesses from 2.4 to 13 mm.