Spruce for kerfing

[Bob Schmidt]

I would like to use reverse kerfing for the current mando build and have not been able to find any premade for mandolins so I am thinking of making my own. I have some spruce scraps that I could use but it does not seem to be used for kerfing. Is there a reason for that or is it just not a popular choice?

[sunburst]

...it [spruce] does not seem to be used for kerfing. Is there a reason for that or is it just not a popular choice?

I suspect the main reason is tradition, though many violins have spruce linings and I don't see any reason it would not work for reverse kerfed linings.

[rcc56]

Agreed.

Several woods have been used for linings. Some violin makers use willow. I've seen mahogany used in some guitars, though it would not be my first choice.
I have used spruce to repair or replace damaged linings in instruments that I've opened, and no problems have come to my attention.

[Rob Roy]

I've used poplar for self made linings on many instruments. It's inexpensive, relatively light weight, machines beautifully, and is strong. After repairing top cracks on instruments, I would be concerned about spruce cracking along the grain lines when under pressure.

[Magnus Geijer]

I have used spruce linings in a number of mandos, guitars and ukuleles. No issues. And as John mentioned, it's commonly used in violins.

Thanks,

Magnus

[HoGo]

I recall (but memory may fail) someone here posted mandolin linings made of two layers of solid spruce. Perhaps James Condino?
I don't see anything bad about it but I would make sure to orient grain parallel to sides to reduce splitting of the "triangles" off the kerfed lining.

[ProfChris]

I've made spruce kerfing, but it's very brittle so tends to snap rather than bend. Hardwoods tend to behave better.

Solid spruce linings work well though.

[sunburst]

...I would make sure to orient grain parallel to sides to reduce splitting of the "triangles" off the kerfed lining.

The OP mentioned reverse kerfing. Probably no "triangles".

[Tavy]

The OP mentioned reverse kerfing. Probably no "triangles".

Either way, I would worry about the blocks separating from the "strip". And yes, hardwoods bend more easily and reliably IMO.

[Bob Schmidt]

Yes it would be reverse kerfing, and my plan was to help bend it on the hot pipe, but if poplar or basswood would eliminate the hot pipe bending they may be a better choice.

[sunburst]

Bending kerfed lining is generally straight forward. The kerfs leave a thin ribbon of wood that bends without the need for heat; just put it in place and it follows the curve of the rim. That will work with spruce.

One thing; with "normal" kerfed linings, where the kerfs face away from the rim, it really doesn't matter if the ribbon breaks. If you are using reverse kerfing in order to stiffen the rim before the plates are glued you don't want the ribbon to break and so basswood (or other) might be a better choice.
Another thing; if this is a flat top/flat back type mandolin and you plan to tuck brace ends into notches in the linings, you might not want to use (tulip) poplar. It is a tough wood and cutting the notches in poplar linings with a chisel is much more difficult than bass, mahogany, spanish cedar or some other woods more commonly used for linings (I learned this the hard way).

[Bob Schmidt]

Thanks everyone. I managed to get some basswood so I am going with that. It is for a carved top and back so no brace issues.

[amowry]

As John said, one downside of reverse-kerfed lining is that if it breaks the break is visible so you have to scrap that piece. I use reverse-kerfed basswood on my instruments, and I have to dampen it in the areas of tight bends so it doesn't break. Then I clamp it in place (or in a mold) to dry overnight and glue it the next day. It adds quite a bit of time over normal lining, but I like the added stiffness. One thing you cannot do is dampen it and glue it immediately, because when it dries it will put tension on the sides, messing with your outline or breaking something.

[j. condino]

It is kerfing; don't overthink it!