A question that is unlikely to keep many of you awake at night, but one that we get asked regularly enough to feel that it’s worth answering.
The definitive answer is in short, it could be either, neither or we don’t really know (or possibly care).
Dealing with the ‘neither’ first. A lot of straight-grained material is produced when logs are flat or plain-cut. This for many species remains the most common form of slicing, especially when the features of ‘crown’ featured veneer (created by cutting across the growth rings) is required. However every log at its core has ‘heartwood’, dark defective and brittle wood that either can’t be used or no one wants to use to make veneer. The wood either side of this is perfectly once this defective centre is removed, but because the growth rings are running at 90 degrees to the knife the veneer produced is straight-grained in appearance – see right of diagram below. So from every flat-cut log we get some straight-grained material which we wrongly refer to as quarter-cut.
The left of the diagram shows how true quarter-cut veneer is actually produced. The round log is fully quartered prior to cutting and then positioned so that the growth rings run more or less at 90 degrees to the knife. However as you can see from the diagram there are going to be some very narrow widths of veneer produced unless you use only the largest and therefore the most expensive logs.
Rift-cutting similarly quarters the log first (or even divides it into thirds), but it has to be cut on a different type of machine, one that spins the log around a fixed knife as opposed to one that simply moves the log up and down against one (see diagram below). There are two advantages to this, one it will increase, albeit only slightly, the width of the slice and secondly it will minimise the prominence of medullary rays (these are the dotted lines on the diagram below). This is especially useful when slicing Oak where these rays are very visible and not normally desired.
Of course I say this, but to contradict myself slightly there is an increasing demand for a specific type of flakey or splashy Oak where you at a very acute angle almost along these rays (next time you accidentally stumble across the Parliament Channel and see the riveting coverage from the House of Commons, focus not on the poorly, dressed pompous, wind-bag giving their speech and try to spot the wall panelling and the mirror like bars going across it… yes only a true veneer geek bothers to watch the Parliament Channel in order to look at the wood wall-panelling).
Sorry back to the point, unfortunately there are problems with rift-slicing, not only does it need a special machine which generally runs slower than a flat-slicer, but also and most importantly, it yields the lowest amount of finished material, especially when one bears in mind that this method is usually employed when slicing the largest, most expensive logs. As a result true rift-sliced veneer will be more expensive than any other type of slicing.
*taken from www.forest products.com.au
And finally, you might not actually be best served by insisting upon rift-cut veneer. Buy cutting in an arc across the grains it increases the width between them, yet too often we see a specification that contradicts itself requiring rift-cut European Oak with a tight grain. And here we come to the ‘don’t really know’ (and in truth normally care) as in reality even the most experienced eye can often not spot the difference between the three different types of slicing, as different logs will lend themselves to different ways of slicing and being a natural product it will vary. One must always remember it’s a means to an end, if it looks nice and has the ‘tight, straight-grain’ you are specifically looking for, should you worry as to the technical detail of how it is produced? So please don’t let this question keep you up at night, I suggest you worry more about the ever increasing price of straight-grained Walnut, now there is a problem.Share