turning brittle wood

[Wes Ramsey]

I have another dozen or so chunks of spalted sycamore like what I used for the vase I posted a few weeks ago. I'm getting ready to turn another few pieces out of the same wood, but want to reduce the amount of time I spend sanding. The end grain is very brittle and no matter how sharp the gouge or scraper or how light the final cut the end grain breaks, leaving lots of sanding to smooth it out. I'm still working on tool presentation technique so I'm sure I will improve over time, but is there something I can put on the wood to harden it or fill it the torn/broken end grain before making a final pass or 2? Any other suggestions?

[Leo Van Der Loo]

I have another dozen or so chunks of spalted sycamore like what I used for the vase I posted a few weeks ago. I'm getting ready to turn another few pieces out of the same wood, but want to reduce the amount of time I spend sanding. The end grain is very brittle and no matter how sharp the gouge or scraper or how light the final cut the end grain breaks, leaving lots of sanding to smooth it out. I'm still working on tool presentation technique so I'm sure I will improve over time, but is there something I can put on the wood to harden it or fill it the torn/broken end grain before making a final pass or 2? Any other suggestions?

You can try wetting it, use soapy water, it will swell the endgrain a bit, and should help CUTTING it, NO scrapers, as the tearouts will be so deep that light finish cuts wont take it all out, you can also use oil or even shellac, but make sure your gouge is sharp and have it slice the grain, HTH

Oh ja, Sycamore is NOT in the Maple family Reed, at least not here in N America , it is in the Platanus family, not the Acer family, just so you won’t get confused some more

[Reed Gray]

Hmm, sycamore spalts really easily, probably because like most in the maple family they have a lot of sugar in them. I am thinking that rather than being brittle (hard so it tends to break rather than cut) it is soft and punky so again, it tends to rip rather than cut. If this is the case, and you are turning in standard bowl/side grain orientation, you need a really high shear angle. Most gouges can go to 45 or so fairly easily. I prefer the fluteless gouge from Doug Thompson for this cut especially with really difficult woods. With it you can go up to 80 or so degrees. If you have a swept back gouge, you can get that high of a shear angle by really dropping the handle, but this only works on the outside of the bowl. Impossible to do on the inside of the bowl. Some of the bottom feeder type gouges can help a bit, but again I prefer the fluteless gouge. I have a video up on You Tube just on the fluteless gouge. Type in robo hippy, and it will come up. Like Leo says, wetting the wood helps. Water, soapy water, walnut oil, etc. work. Get the wood damp, let it soak in for 60 seconds or so, and then cut off the wet wood in very light cuts. Some use wood hardeners or sanding sealer.

robo hippy

[Wes Ramsey]

Thanks guys. I'm turning a cookie jar out of this wood now and will have to try the finish cuts wet with Danish oil next time I work on it.

[Reed Gray]

Okay, a cookie jar, so is that end grain like a big hollow form? That cuts a lot differently than a bowl. Outside is fairly easy, cut from high point/big diameter to low point/small diameter. Most spindle gouges will do this fine, or even a skew, but a skew isn't generally used on larger diameter pieces, say bigger than a rolling pin. Inside is much more difficult, as you have to cut from small diameter to large diameter, so if the top is narrow, you start your cut there, and push, and for the lower part, you pull from the bottom towards the top, if that makes any sense. Most of the time, since is is more of a hollow form, you are using hollowing bits, which are usually scrapers. Getting one of those to a shear angle is more difficult. If the wood is firm, you can use a negative rake scraper, and that can clean things up better than a regular scraper. Hope this makes sense. I don't have a video of this type of cutting up. On some hollow forms like a cookie jar, and boxes you may not want to use a solvent based oil finish on the inside, because the smell never seems to go away. A spray lacquer like Bulls Eye, or maybe Deft can be better, or just a wax finish.

robo hippy

[Wes Ramsey]

Okay, a cookie jar, so is that end grain like a big hollow form? That cuts a lot differently than a bowl. Outside is fairly easy, cut from high point/big diameter to low point/small diameter. Most spindle gouges will do this fine, or even a skew, but a skew isn't generally used on larger diameter pieces, say bigger than a rolling pin. Inside is much more difficult, as you have to cut from small diameter to large diameter, so if the top is narrow, you start your cut there, and push, and for the lower part, you pull from the bottom towards the top, if that makes any sense. Most of the time, since is is more of a hollow form, you are using hollowing bits, which are usually scrapers. Getting one of those to a shear angle is more difficult. If the wood is firm, you can use a negative rake scraper, and that can clean things up better than a regular scraper. Hope this makes sense. I don't have a video of this type of cutting up. On some hollow forms like a cookie jar, and boxes you may not want to use a solvent based oil finish on the inside, because the smell never seems to go away. A spray lacquer like Bulls Eye, or maybe Deft can be better, or just a wax finish.

robo hippy

Yes it is a typical HF and not so much a bowl. So are you saying to cut uphill? Tim Yoder would frown on that I am hoping the smell goes away before next summer when I need to deliver it. I was planning on a simple wax and oil finish, but this wood deserves a shine at least in the outside. I will have to try lacquer after the DO has time to fume out. Or I may turn it thinner and seal the bare wood with lacquer. I'm not sure how to post pics with my phone, but I posted some pics a while back here. This is the wood I'm working with (first one):

http://www.sawmillcreek.org/showthre...t-finished-HFs!

[Reed Gray]

Always cut down hill. So if the outside is kind of () shaped, you cut from the center to the ends, and on the inside, you cut from the ends into the center. For roughing, it doesn't make a whole lot of difference, but for finish cuts, it is really important. A video would explain it better, but I don't know of any like that specifically. Maybe some day for me....

robo hippy

[charlie knighton]

agree with Reed//.....negative rake scrapper

[Wes Ramsey]

I see what you're saying. I'm a member of the local club here and they do regular demos, but I haven't had time to watch any in some time. I do watch a lot of youtube videos and really enjoy Yoder's show, and those are where I pick up tips for improving my technique. The uphill/downhill bit makes sense to me so I try to emulate it. I'll have the check out the negative rake scraper. For hollowing I have the full-size Sorby Hollow Master which works great as long as I don't try to take too much off at one time. What is the difference between a dedicated negative rake scraper and the round scraper that comes with the Hollow Master?

[Faust M. Ruggiero]

Wes,
A few years ago I acquired a big spalted sycamore log, I turned many pieces from it and encountered what I believe you are referring to as "brittle wood". If your wood is like mine, those areas are really places where the spalt has gone too far and the wood has spots of rotted wood (white fungus) intermixed with the healthy wood. If it literally crumbles when you cut it, try using a thinned out shellac mixture to firm up the wood. You cannot soak the blank but can continue to add thin coats as you turn. It dries quickly. If you decide to use oil you will have to wait for it to polymerize before it will be effective. Any finished used to stabilize the wood is only effective on the surface and just below since it can only soak in so far. Then it must be reapplied and allowed to dry. It is a slow and tedious process but the results will be worth while.

[Wes Ramsey]

Wes,
A few years ago I acquired a big spalted sycamore log, I turned many pieces from it and encountered what I believe you are referring to as "brittle wood". If your wood is like mine, those areas are really places where the spalt has gone too far and the wood has spots of rotted wood (white fungus) intermixed with the healthy wood. If it literally crumbles when you cut it, try using a thinned out shellac mixture to firm up the wood. You cannot soak the blank but can continue to add thin coats as you turn. It dries quickly. If you decide to use oil you will have to wait for it to polymerize before it will be effective. Any finished used to stabilize the wood is only effective on the surface and just below since it can only soak in so far. Then it must be reapplied and allowed to dry. It is a slow and tedious process but the results will be worth while.

Thanks Faust! That sounds like exactly what I'm encountering. It doesn't crumble per se, but not far from it. I've been wanting to get some shellac to try a homebrew friction polish recipe so I think I'll give it a shot. Would a shellac-based friction polish (like Eddie Castelin's Shine Juice) do the same thing as well, or does it require the strength of thinned shellac? I'm thinking the BLO would help it get into the grain a bit more. Might have to try it both ways...

[Lloyd Butler]

If I planned on using an oil finish at the end, then I would use an oil based varnish thinned a bit and lightly painted on the end grain inside the cookie jar to help stiffen the fibres and fill in between them a bit. If the final finish is water based, then a quick drying water based varnish to help stiffen the fibres. An oil like BLO or Danish oil take a long time to dry and will not fill the pores between the fibers to help stiffen them, making them a less than ideal choice.

you will likely not cut away all the finish used to help stiffen the fibers, so try not to mix them (oil stiffener, water based finish or water based stiffener and oil finish) as you will have some sealed end grain and some open end grain leaving botching.

you'll need a nice light touch to try and scrap the tearout away. If you have a hunter tool, or termite tool you may be able to cut the end grain once it is stiffened.

[Faust M. Ruggiero]

Wes,
I can't answer your question about a shellac based friction polish. Don't over complicate the problem. Keep it simple. Turn till you are within 1/8" of a finished product then use shellac. It will stiffen the fibers. I wouldn't bother with the inside. If you do, don't pour shellac into the vessel thinking a good soak will harden the fibers. The vessel is apt to crack from the rapid expansion and contraction as the alcohol dries. Guess how I know that. For a cookie jar, you can apply lacquer, wipe on poly or even salad bowl finish over the shellac. Oil might not be your best option for heavily spalted wood. It may not harden enough. However, if you want to try oil, just take a piece of scrap. Shellac it then apply the oil. You will quickly know if you like the result without risking your vase. Good luck and post a picture. I'll bet the finished product will look great.
faust