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The terms hardwood and softwood are often used, but I struggle to find a reliable definition.

Is the wood's density sufficient as the distinguishing feature?

Is it the only one?

As oil is known to harden a wooden surface, is it possible to create a (in terms of density) hardwood-like surface on a piece of softwood? Is it even possible to get softwood that's harder than (relatively soft) hardwood this way?

Crucial edit

When I asked for hardwood and softwood, I had the German terms “Hartholz” and “Weichholz” in mind. It turns out they do not translate one-to-one: In English, according to Wikipedia and ON5MF's answer, the distinction is made by the type of tree from which the wood is harvested. That corresponds to the German terms “Laubholz” (wood from dicot angiosperm trees, = hardwood) and “Nadelholz” (wood from gymnosperm trees, = softwood). The differentiation in “Hartholz” and “Weichholz” differs from that in a way that it takes the wood's “hardness” as the distinguishing feature, and I wondered how exactly this is measured and defined. So, additional question: Is there a similar differentiation in English?

tl;dr: How do you measure a wood's hardness?

  • Oil won't significantly harden a wood surface. You can add a much harder and tougher surface to wood by introducing a resin, usually these days in the form of varnish. You can apply straight varnish lightly so that it penetrates the wood and doesn't sit on the surface as a very noticeable layer, or you can use a purpose-made penetrating finish that contains some varnish, the most common of these in the English-speaking world is "Danish oil", which in most cases is a simple mixture of oil, varnish and added spirits to thin it down. [contd] – Graphus Aug 11 '17 at 7:08
  • Remember that this is surface hardness only, the untreated wood underneath remains just as soft as it started and there's no way to change that, or its structural properties, using only a surface coating. – Graphus Aug 11 '17 at 7:10
  • 2
    Possible duplicate of What is the difference between hardwood and softwood? – Matt Aug 12 '17 at 3:12
  • @Matt I read this question, but it doesn't address a wood's hardness but rather its type, which is a slight but essential difference – see my crucial edit and tl;dr in the question. – dessert Aug 12 '17 at 6:48
  • Well then I suggest you change your title and recommend the answerer do the same. If you are asking how to determine a wood hardness I don't think the current answer addresses that and the first half of your question is misleading if that is the case. My answer to the potential dupe also discusses wood hardness and that testt. – Matt Aug 12 '17 at 16:27
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Technically hardwood comes from angiosperm trees, softwood comes from gymnosperm trees.

So (mostly) if the tree has leaves it is hardwood, if it has needles it is softwood.

This means that some 'hardwood' species can be a lot softer than 'softwood' species.

Examples of hardwood: beach, oak, birch, balsa (which is very soft)

Examples of softwood: spruce, pine, fir, cedar

  • Thanks for your answer! There was a misunderstanding, I updated my question. Do you know any similar differentiation? – dessert Aug 10 '17 at 19:02
  • There is a test for the hardness of wood: the Janka hardness test (see wikipedia). I am in the wood business but mostly for the hardness we look at the volumetric mass density. The higher the density the harder the wood. The reason for this is that the figures for the density are way easier to find than those from the Janka test. – ON5MF Jurgen Aug 10 '17 at 20:14
  • This is exactly what I searched for: a reliable measure for wood hardness, thanks a lot! Where can I find wood density figures though? – dessert Aug 10 '17 at 20:32
  • At my business we mostly use a book 'Houtvademecum' (in Dutch). I guess a similar book should exist in German and/or in English. The properties for the most common species can certainly be found online as wel. – ON5MF Jurgen Aug 11 '17 at 8:01
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Per your edit, you appear to be looking for e.g. Janka hardness, a standardized measure involving indenting a wood sample with a penetrator and measuring the force required to indent a standard amount.

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