Friction-burn lines on a slope with a wire

[John K Jordan]

(As asked about in another thread about finger tops: http://www.sawmillcreek.org/showthre...91#post2755391)

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To friction-burn lines on a slope on a turned wooden object.
JK Jordan, 12/13/2015

I developed this technique about 15 years ago. Maybe others do the same thing but I've never seen it nor have any of the many people I've shown over the years.

Basically, I interrupt the finishing cut partway down the slope to form a groove, friction burn the line, then continue the finishing cut. For example, suppose we want to burn two lines on a slope like in this photo:

Tops00_small.jpg

We want to create the two lines on the left slope as shown in the profile in this sketch. The black dots on the profile represent the desired burn marks.

FrictionBurn_slope_sketch_revised.jpg

Step A: Leave the surface a little bit higher than the desired profile as shown by the green line. I never measured, certainly less than 1/16", doesn't need much.

Step B: Cut the final profile down to where you want the first burn line. Hold the wire in the little valley and burn the line.

Step C: Continue cutting the final profile down to where you want the second line and repeat the burn.

Finish: Continue cutting the to the end of the profile.

NOTES:
- Since the top part of the burn mark will be cut away you may have to burn a little deeper than you would on a normal friction burn.

- When continuing the profile cut as in step C be careful not to cut into the burn mark or you may cut it away!

- I often make just a whisper of a cut over the line if I want the line to be thinner (less deep) but this requires a careful cut to keep from removing the line entirely and having to start over.

- Sanding too much will remove the groove! Sharp tools and a careful hand on good wood should require little no sanding. (I usually hit it with a touch of 600 grit.)

- Most of the wires I see used to friction burn lines are too thick for my taste. I have a stash of thin galvanized wires made to attach tags to valves. I don't know the gauge. Without measuring I'll guess they are 0.2 or 0.3 mm.
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JKJ

[John Keeton]

Good tip, JKJ! I like the unwound and used B and E guitar strings for burning. They seem very durable.

[Jay Mullins]

Good idea John, though I don't think the nylon strings on my guitar would burn very well. ( LOL)

Jay Mullins

[John K Jordan]

Good idea John, though I don't think the nylon strings on my guitar would burn very well. ( LOL)

Jay Mullins

Ha! I play classical guitar too.

Anyone who comes to visit goes away with a few of my all-time favorite burning wires to try, what I've been using these last 15 years or so. They are very thin galvanized steel lock-out tag-out wires. I have a lifetime supply.

While on the subject of wires for burning, another tip: for more friction and cleaner and faster burning I use a piece of say 400 grit sandpaper and it pinch around and pull it down the wire a couple of times to rough up the surface.

JKJ

[Roy Petersen]

It should be common sense, but I'll say it anyway:
If you're holding a bit of wire against a turning while it's moving, wrap both ends around a dowel or pencil. Thin wire tends to catch at times, and it could easily remove a finger if wrapped around one or more to keep it from slipping.

[Mark Greenbaum]

Good tip, JKJ! I like the unwound and used B and E guitar strings for burning. They seem very durable.

I have been using a used low E guitar string with wood handles on each end and it's durable. The wound string provides more friction, and starts the burn quicker. Note: Make sure the smoke detector is far enough away. Don't ask how I know.

[John K Jordan]

I have been using a used low E guitar string with wood handles on each end and it's durable. The wound string provides more friction, and starts the burn quicker. Note: Make sure the smoke detector is far enough away. Don't ask how I know.

I've used the wound strings too and they work well on larger turnings like french-style rolling pins and bowls.

The problem I had was the fatter strings made lines too big for things like the little tops, some close to an inch in diameter, some a bit larger. I often put fine lines on the rims as in some in the second picture, not too practical without a very thin wire.

top_IMG_4974.jpg P3131882es.jpg

Thinner lines are good for detail in a variety of small diameter spindles, often in tight places.
wands_bowl_P7203947cs.jpg wand_holly_carved_P7203954.jpg

This makes me imagine a niche market opportunity for some enterprising person - a set of very durable wires in a graduated variety of sizes from thick to extremely thin, each manufactured with a rough surface surface for the friction. Made from some alloy, HSS, stainless steel, steel core coated with titanium nitride, ??? You might go broke with the development but hey, think of the fame!

JKJ

[Richard Dooling]

Thanks John!

[Roy Petersen]

I often put fine lines on the rims as in some in the second picture, not too practical without a very thin wire.

Have you ever "smoked" the edge, John? On some of the items I made, I bunched up some thick paper toweling and held that to a thin edge until it did much like the wire and scorched the thin edge of the item very softly, kind of a smoky effect. Not recommended for lips of drinking vessels (the heat is bad for thin end grain), but the edge of the top may look interesting with it.
Just make sure it's quite thick, and know the paper will get rather hot and potentially smolder (as will your fingers).

[John K Jordan]

Have you ever "smoked" the edge, John?

Yes (accidentally while burning with a wire!) and I liked the look. Seems it wouldn't work with the method of burning on a slope since you'd have to cut away at least half of the smoked surface. I'll have to try your method on a spot without the wire.

I've darkened light wood with with a small piece of cloth held in a groove. A few days ago I wondered if holding a tiny flame from a micro torch on a spinning piece. (Could be exciting if done over a big pile of shavings!) This might work for thin end grain too since the flame could probably darken the surface without heating the underlying wood, sort of like searing a the outside beef roast before putting it in the dutch oven.

JKJ

[Marvin Hasenak]

I use a scrap piece of Formica for lines on platters and plates, I am sure it would also work on the angle cuts. Speed needs to be high.

[John K Jordan]

I use a scrap piece of Formica for lines on platters and plates, I am sure it would also work on the angle cuts. Speed needs to be high.

Deja vu for me!

A long time ago I described this technique on another forum and it generated discussion, some from interested turners and of course a few from people with other ways of burning lines. The only problem, at least for the little finger tops I make, was I had tried every method mentioned and I could make none of them work as well as the wire method I had devised.

But I'm certainly willing to learn. One experienced woodturner on the other side of the country was insistent that his method with formica was superior and much quicker and would give the same result on the little tops. That turned out to be not the case. I sent him a finished dogwood top with the lines burned with the wire and invited him to duplicate it then educate me and the other readers. I think I also sent a piece of the same wood. The gentleman wrote back (privately) and said he could not get close to the look of what I sent. (He must have gotten busy since he forgot to update the public message thread with his findings...)

The wire method makes lines that are thin and crisp and uniform and will leave black lines that are slightly dished below the wood surface and nicely polished by the wire so they catch the light as you turn the piece in the hand.

It seems to me what to use for burned lines depends both on the scale and the shape of the piece (and the desired look, of course). The formica did work but made larger lines, perhaps perfect for larger things. It may not be useful on the little finger tops simply because of the size. The small diameters present another problem - it is difficult to get the surface speeds high enough. On the other hand, the wire method would not work on a flat surface such as the face or rim of a platter.

From my experiments the formica method works better if you cut a tiny grove into the wood first so the formica doesn't slip, shape the formica scrap to a knife edge, and turn at a high surface speed of course. I found it worked better in some species of wood than others. The wire works well with almost any species I've tried except for some oily/waxy woods like lignum vitae.

Another way I know to make a line on a slope is to cut a groove into the wood first with a tool then fill it with a dark paint/paste/grain filler. The surface (and the groove) needs to be cut cleanly and may need to be finished beforehand to avoid bleeding with some fillers. The edges of the groove need to be very smooth since any roughness at the surface will show up with the contrasting filler - probably best cut (not scraped) with the tip of a sharp skew. Any filler smeared on the surface may get into the pores and make a mess. All this is avoided with the wire on a slope method. One advantage with the filled groove method is the ability to use colored fillers instead of black. Light blue lines on ebony would look nice. I've also filled such lines with brass and other powder for a nice look. I sent these things to a friend in Italy (I turned the brass feet and finial for the box on the wood lathe):

brass_finial_ring_IMG_2384.jpg
(sorry for the poor photo)

JKJ

[Steve Mawson]

Formica works much better if it is sanded down to .015-.020 thickness, sand off the surface that has the pattern on it. If left at the thickness of the countertop material it's hard to get hot enough, at least for me. 1/2-1 inch wide piece does the trick. A drum sander works well to accomplish this task. I got the idea from Harvey Meyer as this is how he darkens the groves on his illusion vessels and it works well.

[Kyle Iwamoto]

Formica works much better if it is sanded down to .015-.020 thickness, sand off the surface that has the pattern on it. If left at the thickness of the countertop material it's hard to get hot enough, at least for me. 1/2-1 inch wide piece does the trick. A drum sander works well to accomplish this task. I got the idea from Harvey Meyer as this is how he darkens the groves on his illusion vessels and it works well.

Thanks! I've used Formica and not had really good results. Now I know why......

[John K Jordan]

Formica works much better if it is sanded down to .015-.020 thickness, sand off the surface that has the pattern on it. If left at the thickness of the countertop material it's hard to get hot enough, at least for me. 1/2-1 inch wide piece does the trick. A drum sander works well to accomplish this task. I got the idea from Harvey Meyer as this is how he darkens the groves on his illusion vessels and it works well.

Steve,

Did you try this on something the size of the little tops? The first thing I did when I experimented with formica was sand it thin. This works well for larger things with grooves like Harvey does but in my experience not on the little tops. (BTW, I measured the wires I use for fine lines on small turnings - about 0.015" diameter.)

Try this:
- Chuck up a piece of dogwood or hard maple (or even holly) at least an 1" square, long grain along the spindle axis.
- Turn a smooth cone on the end at a fairly steep angle, about 60-70 degrees, with a skew or spindle gouge.
- Try burning a clean line about 3/4" away from the spindle axis.
- Maybe post a closeup picture of the result.
My tries with formica on small turnings were discouraging. I look forward to seeing your results.

The next time I see Harvey I'll ask him if he's tried the formica on small diameter end grain.

JKJ