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Products> OSB FAQs> Production & Raw Materials

Production & Raw Materials

Production

What kind of wood is used for OSB production?

Only virgin debarked coniferous wood (mainly spruce, pine, fir) and deciduous wood (beech, birch, poplar), without defects (knots), are used in the production of OSB.

Why is softwood preferred to hardwood in OSB production?

The wood species commonly used in the OSB production are:

1. Softwood (coniferous wood): spruce, pine, fir
2. Hardwood (deciduous wood): beech, birch, alder, ash

The reason why softwood is preferred to hardwood is because softwood generally gives a lighter appearance on the board surface, and because its swelling rate is lower than that of hardwood.

Resulting from different growth pattern, softwood is also lighter in density than hardwood, so its strength and stiffness are lower.

Consequently, softwood requires more strands than hardwood to reach the same strength values, but this is actually beneficial for the board, because it gives higher compactness of the surface layers.
As far as the stands are concerned, the strands of softwood are typically long and thin, whereas hardwood strands are wider, thicker and more brittle in the middle.

What gives OSB such great stiffness?

The special strand distribution in the core and surface layers (crosswise orientation), the shape of the wood strands (long and thin) and the quality of the wood used in OSB (fully debarked, non-contaminated, free of knots, non-recycled, free of sand, dust and metal inserts) result in great stiffness.

What are the factors that determine the type of board?

There is not a single factor, but a mix: from wood selection (proportion of softwood and hardwood), to different mix of binder components (resins, emulsion and water), the relation of surface/core layers, and of course, the pressing rate and heating temperature.

Why does EGGER OSB have such a smooth surface? Is that an advantage?

The smoothness of the OSB boards comes from the continuous ContiRoll pressing, but also from the wood selection, the quality of debarking & stranding, wax and PMDI content.

The advantage of the smooth surface is that is gives the boards an additional moisture protection for about 4 weeks.

Raw Materials

What is MUF and what is PMDI?

MUF (melamine-urea-formaldehyde) and PMDI (polymeric diphenylmethane diisocyanate) are the two most common synthetic resins used in OSB manufacturing, for bonding the strands to each other while pressing.

The difference between them is that PMDI does not include the formaldehyde component in its chemical structure, so this is why PMDI-bonded boards are commonly referred to as “formaldehyde-free” OSB panels. These boards can be produced by using either one single resin (MUF or PMDI) in both core and surface layers, or by using a combination of the two (typically: MUF in the surface and PMDI in the core).

The decision of using one or another type of resin belongs of course to the manufacturer, and is more related to availability and price volatility of each type.

What are the differences between MUF-bonded and PMI-bonded OSB boards?

Except for the difference in the formaldehyde content (HCHO emission for MUF < 0,1 ppm / for PMDI < 0,03 ppm), there is absolutely no difference between boards.

All relevant physical and mechanical properties are identical and the boards are classified the same.

Does OSB contain any hazardous components? Is MUF resin dangerous?

No. Cured glue is not hazardous for human health, but care must be taken in the production process, which is under external monitoring.