Just made a bowl for my granddaughter. I took a lot of care over it and was especially proud of the finish I achieved. When I gave it to her she said " Gee, thanks granddad, it looks just like plastic". I think that probably we can go too far with this finishing lark and we are likely to loose sight of the beauty of the wood itself. The finish should enhance not detract.
Tom
Hi Tom, I couldn't agree more and I have been guilty of making plastic looking woodturnings. It's something I have been struggling with all the time I've been turning. I think as woodturners we sand too high. I rarely sand above 320 or 400 anymore. If the finish is going to be lacquer 320 is fine. I'm sure most will say this is not high enough but it's what works best for me. I believe sanding to very high grits is the beginning of a plastic looking turning. Lately I have been using a very simple finishing method that works very well with most woods. After sanding to 320 apply a couple coats of Danish oil and let it dry for a week. The Danish oil makes the color and the grain pop out. Less than a week and this won't work. The oil needs to cure. Then
2-3 coats of a good quality finishing wax and buff. This gives a finish almost anyone will like. It gives a real nice sheen and feels nice too. I do a lot of segmented work with very dense exotics and sometimes use lacquer. I've found that sanding the actual finish to too high a grit will result in a plastic looking turning. I used to spray a couple coats flattening between with 4/0 steel wool and have found this makes a plastic looking turning. Now I sand between coats with 320 grit paper and this reduces the plastic look. I can't tell you why this works as it goes against the theorie of lacquer but it works for me. Bob
Tom, Like you, I have been on a quest for the ultimate finish, and have dabbled with most of the contemporary finishes. I can offer you my personal opinions on what I have perceived to be the strengths and weaknesses of each.
Oil (BLO, Walnut, Tung, Mineral) Easy to apply and repair. Catches dust, generally requires reapplication as maintenance. Only walnut and mineral oil are considered food safe. Not waterproof. Can take weeks to cure, depending on the blend. Luster rather than gloss, but can be waxed and polished to a pretty high sheen. Some woods absorb irregularly and may look splotchy over time.
Petroleum based Poly Slow drying time, but faster than oil. Fumes toxic. Very hard, and tends to crack rather than moving with wood. Can achieve high gloss. Waterproof. Solvent proof. Not easily repairable. Yellows over time and can aggravate glue creep. Probably food safe unless you eat the turning.
Water-borne Poly Fast dry time. Fumes moderately toxic. Hard, seems to move better with wood than spirits poly. High gloss can be achieved. Water proof once cured. Resistant to most solvents, including alcohol. Not easily repaired. Doesn't yellow or affect glue. Can blush. Probably food safe, unless you eat the turning.
Shellac Easy to apply. Very fast drying time. Fumes annoying. High gloss can be achieved. Water proof, but not alcohol proof. Fairly easily repaired. Nice depth. Comes in a variety of "colors" depending on the degree of purification. Can yellow, but the ultra-blonde 100% dewaxed I've been using hasn't yet in several years. Definitely food safe if you enjoy eating bug secretions.
Nitro-Lacquer Very fast dry time. Extremely toxic fumes. High gloss can be achieved. Water and alcohol proof. Not easily repaired. Doesn't yellow, seems to offer a lot of "depth". Can blush. Probably food safe if you don't eat the turning.
All of these may (and with the exception of oil, should) be leveled by sanding between coats, but sandpaper clogs quickly with shellac. Fibre pads and steel wool are preferred by me when applying shellac. Do not use steel wool with acrylic poly. I apply multiple coats, sanded in between, of all finishes. Too coarse or too fine grades of sandpaper (< 220 or >320) should be avoided except on the final coat. I tend to avoid highly polished "plastic dipped" finishes as they detract from the character of the wood.. I generally reserve oil for cutting boards, etc. 1-2 lb cut shellac is becoming one of my favorites - for the quick dry, easy wiping application, and depth. Lacquer is another favorite, for it's durability, resistance to chemicals, and depth, but the fumes are really serious - especially in winter. I avoid petroleum poly period, even thinned wiping poly. The water based poly seems better, albeit a bit "plastic" looking. I apply thin, as a wipe, and sand between coats to avoid excessive build.
On the final coat, I either sand to 400-600 for a satin finish, or you may progress upwards and polish with compounds and wax to really bring out the gloss, but this tends to make wooden items look artificial, kinda like a bowling ball. A satin finish, sometimes waxed with Johnson's non-silicon paste furniture/floor wax, is my personal preference. Whatever you and your market prefers should be yours. Either way, it is important to make certain the sanding swirls are removed before applying any finish. You can wet the wood with alcohol or naphtha under good lighting to highlight sanding marks.
My 2 cents worth... FWIW,
Greg G.
You've never eaten M&Ms?
Yes, I know.
Greg G.
Hi Greg, This may just be a typo but a lacquer finish is by far the easiest of all finishes to repair. Most lacquer repairs can be done simply by adding more lacquer to the affected area. Even blushing can be repaired occasionally by adding more lacquer. Blushing is not a lacquer problem but a problem created by the person applying the lacquer either by applying it when the RH is too high or by an incorrect mixture. Lacquer having the ability to melt the previous layer is what makes it so easy to repair. And unlike other film finishes you can spot repair rather than having to refinish the whole piece. Bob
You say only walnut and mineral oil are considered food safe ??? Unless extracted without the protein walnut oil is no safer than peanut oil for allergy sufferers. Mineral oil is used as a laxative, as the body rejects it and all that's in there with it ;->. Pure tung oil is food safe, here's some info to that extend.
;-)
Greg G.
Well... that's an allergy problem, not an innate toxicity problem for most people, but I understand...
In quantity, yes. You may not be aware that many food and candy products are coated with mineral oil. Gummy bear/worms and pectins to mention a few.
And of course, shellac is used on food products sold at the grocery as well. M&Ms for instance.
Thanks, Leo.
Greg G.
I never heard anyone being able to make a "coat" with extra refined engine oil, as that's what mineral oil is basically, it will never harden, and a bag with candy with the bottom having a bunch of oil in it doesn't sound to appetizing to me, but I do know that Carnauba wax and also shellack is used as a food/candy glosser/cover
unlike line seed oil. tung will polymerize much faster, usually in less 24 hours in warm conditions.
Hi Greg, Yes I have to agree about the blush but only when conditions are incorrect. I hope all have a nice holiday. I have actually sent a letter to santa requesting all get that turning tool they have been wanting. All except for Greg who I have requested that santa send him a half dozen highly colored exotic hardwood boards for the kaleidoscope turning we all expect to see from him the first of the year. :-) Sorry Greg I couldn't resist. All in good fun. Bob
Bob, I'll second your first request with the addition of a small load of scrap M2-11 steel so that everyone can build their own endless supply of turning tools with creativity and ingenuity as their guide.
As for me, wood is always good. It's getting pretty pricey these days. I'd like to build more furniture, but the wood costs a chunk. The segmented woodturnings are an inexpensive way to experience first hand various woods; their gluing, cutting, and finishing characteristics.
For instance, did you know that if you use water-borne poly on Honduras mahogany, it will pick up a pinkish tinge? How would you like to find that out after applying it to a wall sized media center. (Yeah, I know, always check your finishes for compatibility... And no, it's not moisture, it's a chemical in the poly.) Or that Makore releases a crystalline chemical when glued and will turn soft maple bluish black. Ah, live and learn.
Reality bestows a lump of coal. Being a very bad boy, I'm used to it. Christmas for me used to involve a hot dog from the gas station and a day of cable sci-fi reruns while I fixed electronic crap. Coupled with a desire for the planet to make it through another year without being destroyed by idiots.
Things have really turned around these days, however. Now it's a pizza bought a day ahead, a day of sci-fi and Norm reruns on DVD, and a day of coding coupled with gluing hundreds of little pieces of wood together after first cutting them apart. Now that's progress! ;-)
But all kidding aside - as for the polychromatic turning, you guys shouldn't hold your breath. Then again, perhaps I'll actually try and come up with one that isn't too risque - just for your edification. After all, one can only sell what the market demands. I take cash and dead deciduous trees.
Have a great Christmas, and the same to the rest of the denizens of the group.
Greg G.
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