Finger Jointed S4S Timber -

Finger Jointed S4S Timber - Longer Lengths Reduce Wastage

Finger Jointing is a modified butt joint where shear force is made to transmit compression or tension in wood member. The fingers are usually cut at a fibre slope of 1 : 8 & the cut fingers are glued with special resins & then interlocked with pressure to produce longer lengths.

To achieve high strength, normally the glue area is designed to have around 6 times the cross-section area of the timber.

The timber for jointing are dried to maintain proper moisture content. The joint could be oriented with the finger designs visible at the timber edge or on the flat side. From the point of view of strength, both these considerations are the same.

Its Advantages

Finger Jointed S4S Timber offers the possibility of accelerating the construction and manufacturing activities with reduced wastages while maintaining high quality standards. The user of the wood naturally gets much less wastage if the finger jointed timber in longer lengths are available to his specifications at the construction site. Some of the benefits of Finger Jointed S4S Timber are :

Finger Jointed S4S Timber

Availability of totally defect - free timber.
Better quality & strength of joints as compared to on - site jointing.
Overall reduction in costs - on - site jointing & construction labour costs.
"Cut to Size" convenience.
Freedom for design with long length options upto 20’

Finger jointed S4S Timber can be used as: Door & window frames, partition & false ceiling framework, furniture, beams & purlings (either with or without lamination).

Specifications for Finger Jointed S4S Timber

The Rubberwood for production of Finger Jointed Lumber is pressure impregnated with Boric-Borax / Parachem Anti-Bacterial Chemicals, Kiln dried & normalised. The grade specification is applicable to 1 face & 2 edges and the other face will have the specification with minor defects of the next lower grade.

The Resins for Finger Jointing are polymers (PVAC, PU Combinations) which are either white or translucent. The glue joints are designed to withstand delamination tests conducted after boiling. The depth of chemical impregnation is usually above 70% and is measured by reagents. The toxicity level of the product is low and within allowable limits.

The maximum dimensions of panels are: Length 6000mm, Width 80mm, Thickness 50mm.

Grade	Colour	Finish	Moisture Content	Warpage	Structure	Attributes	Size Tolerances
							Thickness	Width	Length
A	Uniform and evenly matched	Sanded smooth	Below 10%	2mm in 1000mm length	Finger jointed. Minimum length of each plank is 300mm, end planks length 150mm or above.	Free of knots, blue stains, ends & surface cracks, tapping marks, mineral & starch streaks, torn off fingers.	+0.5mm	+1.0mm	+10mm
A/B	Mixed colour by natural variation or Sap / Heart-wood variation	Sanded smooth	Below 10%	2.0mm in1000mm length	Finger jointed. Minimum length of each plank is 300 mm, end planks length 150mm or above.	Combination of A & B grades	+0.5mm	+1.0mm	+10mm
B	Mixed colour by natural variation or Sap / Heart-wood variation	Sanded smooth	Below 10%	2.0mm in1000mm length	Finger jointed. Minimum length of each plank is 300 mm, end planks length 150mm or above.	Free of knots above 20mm dia, pin holes, end cracks, mineral & starch streaks, allowance of blue stain upto 3% of surface area. Tapping marks not more than a total length of 150mm in 1 sq metre surface area.	±0.5mm	±1.0mm	±5.0mm
B/C	Mixed colour and limited blue stain, uneven variation	Sanded smooth	Below 10%	3.0mm in1000mm length	Finger jointed. Minimum length of each plank is 300 mm, end planks length 150mm or above.	Combination of B & C grades	±0.7mm	±1.0mm	±5.0mm
C	Mixed colour, blue stain and uneven matching allowed	Sand finish	Below 10%	3.0mm in1000mm length	Finger jointed. Minimum length of each plank, end planks length 50mm or above.	Allowance of knots, blue stains, pinholes, light cracks & tapping marks, mineral & starch streaks, structurally safe finger cracks.	±0.7mm	±1.0mm	±5.0mm