Questions about a paper joint

[Brian Brown]

I want to make some items that have to be split after turning. A paper joint seems to be the way to go, but I have never done it.

What kind of paper would you use?
What weight?
Is there any magic to one glue vs another?
What are the odds of a joint coming apart while turning?
What is the best way to true the surface of the wood after breaking the joint?
Any other advice?

[Grant Wilkinson]

I use brown paper bag paper, with titebond glue. I've never had one come apart yet, but that does not mean it's impossible. As to "truing" the surface, I simply reverse mount the piece on the lathe and turn away the paper remnant.

[Brice Rogers]

I am not an expert but will share my own experience.

I have used typing/printer paper and also have used newspaper. I don't notice much difference.
I use either Titebond 2 or 3. They both work about the same.
Will it come apart while turning? If you don't get a significant catch, the chances are low. But all bets are off if you get a nasty catch. It'll probably come apart.
Truing the surface afterwards? Sand paper. I have a 10 inch sanding disk that works nicely.
On some parts I have turned a recess in my glue block so that the glue only holds on the outer edge rather than all the way to the center. The holding power is primarily from the outer diameter/edge anyways.

[Robert Henrickson]

I use Titebond II and usually brown paper bags for paper joints; sometimes I've used thinner paper. I wouldn't worry about joint failure -- I have yet to see any glue joint even begin to open during turning. My problem is generally getting the joint to split. If you have a bad catch, it is more likely you will have the turning come out from between centers than that glue joint will fail. I have used it even with long skinny spindles; the spindle itself is more likely to snap in two than the glue joint fail. It is a technique that has been used literally for centuries.

Depends on what you mean by "truing the surface" -- If the glued surfaces are to remain, you can soften Titebond with isopropyl alcohol then scrape. If you use 91% isopropyl alcohol you shouldn't have any problem with raising grain; even 70% doesn't seem to create problems. You can also sand the paper/glue remnants with a blet sander.

[William Bachtel]

I like using a cereal box (light wt cardboard) It is flat and will split apart, and then sand glue off. I have been doing this for over 30 years , never have any trouble with it coming apart.

[Robert Henrickson]

David Reed Smith also uses cardboard. He also suggests using blue masking tape on the glue faces to avoid residue after splitting. It apparently does not affect the strength of the glue joint -- see the process described in detail

http://davidreedsmith.com/Articles/Fish/Fish.htm

I have used this procedure several times and had no problem with the strength of the glue joint, with either a long skinny or more globular block.

[Tom Albrecht]

I have successfully used brown craft paper (wrapping paper) for smaller solid items.

I have had a really nasty accident using a paper joint in a heavy octagon stave constructed column. I had an order for eight half columns in red oak @ 12" D X 4' Height. I only bothered to to make a paper joint on the first column glue-up because it was mess and a real hassle by myself. I glued up the rest of the columns without a paper joint and planned to rip them in a table saw jig (which worked fine). The accident happened when I was finish sanding the last full piece on the lathe, using the same process that I used with the seven previous. But, the last piece on the lathe was the first glue up with the paper joints. Apparently one of the paper joints started to tear apart with the high speed sanding and then all hell broke loose very rapidly as the spinning 12" diameter column disintegrated while ripping apart with the grain into large chunks. Fortunately I was wearing a full facemask and helmet. Overhead fluorescent lights shattered and shards of oak pierced my OSB walls. I was unharmed, but I had to start over on another column.

Obviously I was sanding at a rate that was too fast for a glue joint.

[Brice Rogers]

I forgot to mention - - when using a glued paper joint, try to use a live center whenever possible. Especially when making rough or aggressive cuts. That keeps the forces in "shear" and compression for which the glue joint is very strong. Tension (pull apart) strength of the joint is poor, which is what you plan on when you intentionally separate the pieces. A steady rest can also be helpful.

[Leo Van Der Loo]

The paper to be used has to be thick enough so that the glue does not goes through to the glue of the other side of the paper as then you would have just one thick glue joint.

And in that case it would be very hard or impossible to split the pieces apart.

Also holding the pieces between centers, make sure you use the cup centers and not the sharp pointed center as they could force the two halves appart.

[Brian Brown]

The paper to be used has to be thick enough so that the glue does not goes through to the glue of the other side of the paper as then you would have just one thick glue joint.



Leo,

That is what I thought might happen. That's why I asked about the paper weight. I have a roll of craft paper about the weight of a grocery bag. It sounds like it might work.

[Wayne Lomman]

I use what I call cartridge paper which is probably about 200gsm. Have done since I was shown in woodworking class when I was 13. I just use whatever PVA glue is handy. No failures. Cheers

[John K Jordan]

I want to make some items that have to be split after turning. A paper joint seems to be the way to go, but I have never done it.

What kind of paper would you use?
What weight?
Is there any magic to one glue vs another?
What are the odds of a joint coming apart while turning?
What is the best way to true the surface of the wood after breaking the joint?
Any other advice?


Brian,

I put your question to good friend and amazing turner John Lucas. He is a prolific turner, does many demos in the southeast, and teaches at craft schools.

John does a lot of paper-glue joints for inside-out turnings and numerous other things. His reply:

"just about any paper will work.

The only paper I've found that didn't work well was water color paper. I use mostly newspaper and yellow woodworkers glue. Put the glue on both pieces of wood and then put the paper in between and clamp. I don't use a huge amount of glue because it can soak through the newspaper making it hard to break the joint. I use a thin layer of glue and then clamp. It takes longer for the glue joint to cure than without the paper. A few hours is better than 30 minutes like a normal glue joint. For safety sake I usually glue up at night and then turn the next morning.

If it's a thin turning I use a butcher knife and tap it down through the joint. If it's a thicker piece I just use a chisel and mallet. I have never had a glue joint come apart. If it Is a large piece I might secure the outside with nylon strapping tape. Turn an area and then tape that area and then turn the rest. I did my gun lamp which was 16" at the bottom, 8" at the top and 54" long with a glue joint for the door and it didn't come apart.

After you split the joint if the turned surface doesn't have fine detail in the edges you can use a cabinet scraper to get the glue and paper off. It's it's a more delicate turning use White Vinegar to soften the glue and I use a carpenters chisel as a scraper and gently scrape it off.


I've done a lot of glue joints over the years. They are fun and easy. "

If you have time, you may like to look at some of John Lucas' woodturning videos. I don't think he has one on paper joints but maybe he can be talked into making one!

JKJ

[John Keeton]

One point that I don't believe was mentioned - do not attempt end grain joints, only face grain. Glued end grain joints are weak even without paper.

[Brian Brown]

Thanks John. Exactly the information I am looking for. Please Thank John Lucas as well. I failed to mention that this will be a longish turning in spindle orientation. I always use glass filament tape around any glued turning, and any solid wood that is even remotely questionable. I would definitely use it on a joint like this. I tend to go overboard on the safety.

[John K Jordan]

Thanks John. Exactly the information I am looking for. Please Thank John Lucas as well....
...I tend to go overboard on the safety.

I'll tell him in person.

Overboard on safety - that may be why you are turning wood now instead of learning braille!

JKJ

[Brian Brown]

Overboard on safety - that may be why you are turning wood now instead of learning braille!

JKJ

My thoughts exactly. That's why the shield never leaves my face when I'm at the lathe.

[Leo Van Der Loo]

Leo,

That is what I thought might happen. That's why I asked about the paper weight. I have a roll of craft paper about the weight of a grocery bag. It sounds like it might work.

Sorry Brian, yes brown paper should work just fine, the only thing is how thin the glue is, as in moisture/glue soaking into the paper, applying it to the wood first, rather than to the paper does help for some of the moisture of the glue to move into the wood before it goes into the paper.

Separating is sometimes tricky, as in how delicate is the piece to be separated, I use a old but solid butcher knife that if needed can be helped along with a rawhide mallet, HTH

[Brice Rogers]

I have a neighbor who is a fellow turner. As an alternative to paper and PVA, he uses hot-melt glue. When it comes time to part the waste block, he just sticks it into the microwave for a short time. Then it just kind of comes apart. It is best to let the hot melt reharden on the part as it is easier to peel it off when hard. I have tried it and ended up with a minor amount of residue. I used a sharp chisel like a cabinet scraper and then used a paint thinner to get off the very last remnants. My hot melt seems to dissolve slowly with mineral spirits or paint thinner.

But having thrown out one more way to do this, I prefer the glue block and paper method.

[Wade Lippman]

Thanks John. Exactly the information I am looking for. Please Thank John Lucas as well. I failed to mention that this will be a longish turning in spindle orientation. I always use glass filament tape around any glued turning, and any solid wood that is even remotely questionable. I would definitely use it on a joint like this. I tend to go overboard on the safety.

What do you do with the tape? Use to secure the part you aren't working on?

[Brian Brown]

I use the tape on areas where I am not working. For example. if I am doing a hollow form that has voids or bark inclusions, I'll wrap the outside with glass filament tape to control the explosion that could happen when I am hollowing the interior. In some cases like segmented work I will wrap it tightly with pallet wrap. It won't stop the piece from coming apart, but will help control the shrapnel if it does.