Paper wave/curl caused by office laser printer

[Tradidi]

Just looking at these 3 points, since you're printing onto A4 substrate and step "5" is simply cutting the A4 2-up in half, your finished book hasn't got a cleanly finished knife trim to three sides. As you also have a laminated card cover in the mix, I imagine this lack of final trim to give an even block is quite apparent. You'll also find this trim can reduce the "wavy" effect - we often print and laminate stacks of SRA3 300GSM posters, when looking at them on the bench the next morning there's often a little waviness there, however after chopping them down to A3, it's as good as gone.
On a production machine, you would be printing A5 4-up onto SRA3, centered at 80/112.5mm, 240/112.5mm, 80/337.5mm, 240/337.5mm to give you the full bleed and final trim capabilities.

No, I'm printing A5 on A4 stock, in the centre left and trimming 3 sides (top, right and bottom). There is a lot of wastage like that, but it is still cheaper (in my situation) than buying larger stock and trimming less wastage. And I do end up with a cleanly finished product.

 

[Tradidi]

Take the responses here as our attempt to help you put out the best book possible. With growth the opportunity to upgrade equipment will happen.

I do appreciate all the responses and am learning a lot from them. Thank you to all the people that took the time to reply!

 

[Ynot_UK]

No, I'm printing A5 on A4 stock, in the centre left and trimming 3 sides (top, right and bottom). There is a lot of wastage like that, but it is still cheaper (in my situation) than buying larger stock and trimming less wastage. And I do end up with a cleanly finished product.

oh wow! My bad... I'd incorrectly assumed when you said:

5. Then I trim the A4 books down to A5.

that you were printing A5 2-up on A4

 

[Tradidi]

oh wow! My bad... I'd incorrectly assumed when you said:

that you were printing A5 2-up on A4

I did consider that but then I would end up with short grain A5 which is not ideal, especially for the strength of the binding. Plus, as you said, you either end up with a rough untrimmed edge or I would have to trim even smaller than A5.

 

[Tradidi]

I did consider that but then I would end up with short grain A5 which is not ideal, especially for the strength of the binding. Plus, as you said, I either end up with a rough untrimmed edges or I would have to trim even smaller than A5.

 

[Ynot_UK]

I did consider that but then I would end up with short grain A5 which is not ideal, especially for the strength of the binding. Plus, as you said, you either end up with a rough untrimmed edge or I would have to trim even smaller than A5.

Shame that little printer you have won’t take SRA4, then you could go 2-up

 

[Tradidi]

Shame that little printer you have won’t take SRA4, then you could go 2-up

My inkjet (ET-16600) takes up to SRA3, but the problem is the cost of the paper. Using A4 copy paper is still way cheaper, even after all the wastage. I guess that's because it is mass produced.

No doubt big print shops can get any size paper for a good price, but being a small one man band I cannot afford the volumes yet that I would need to buy in order to access that market, so I'm stuck with making the best of what I can get.

 

[Ynot_UK]

I was speaking of the Kyocera, which you're printing the guts of the books with.

 

[Tradidi]

I was speaking of the Kyocera, which you're printing the guts of the books with.

After reading that even large (laser based) production machines can have these kind of (paper wave/curl) issues, I've decided to dump my Kyocera and go for inkjet only. Their lower power consumption is also a big bonus for me, as I'm running completely on solar power.

 

[Tradidi]

Meanwhile, I've trimmed one of those wavy text blocks in the picture in the OP to A5 size and let it sit in the house for a few days. In other words, I cut off the edges which are the most wavy part. The block now "looks" OK, no more waves are visible, but when you run your finger over the edge you feel it going up and down like a roller coaster. This is only in the short grain direction, not the long grain direction. The long grain direction looks and feels fine.

I am struggling to understand the science behind that. If it was moisture getting out or into the short grain side, would it not happen evenly along the whole edge? And it if was doing this randomly (depending on the consistency of the paper quality) , would it not even out over 100 sheets of paper? So why are the ups and downs of the waves all in the same place along the short edge of the paper, and why can you only feel this but not see it?

My best guess is that either there is something inside the printer that heats the paper more in some places than in other (unlikely), or perhaps it is because there are rollers inside the paper that deform it immediately after the paper has been heated by the fuser (my best guess).

Can anyone help me understand the process? Perhaps that could lead to a solution, or at least to something to look out for when buying a laser printer.

 

[TJPrinter]

Meanwhile, I've trimmed one of those wavy text blocks in the picture in the OP to A5 size and let it sit in the house for a few days. In other words, I cut off the edges which are the most wavy part. The block now "looks" OK, no more waves are visible, but when you run your finger over the edge you feel it going up and down like a roller coaster. This is only in the short grain direction, not the long grain direction. The long grain direction looks and feels fine.

I am struggling to understand the science behind that. If it was moisture getting out or into the short grain side, would it not happen evenly along the whole edge? And it if was doing this randomly (depending on the consistency of the paper quality) , would it not even out over 100 sheets of paper? So why are the ups and downs of the waves all in the same place along the short edge of the paper, and why can you only feel this but not see it?

My best guess is that either there is something inside the printer that heats the paper more in some places than in other (unlikely), or perhaps it is because there are rollers inside the paper that deform it immediately after the paper has been heated by the fuser (my best guess).

Can anyone help me understand the process? Perhaps that could lead to a solution, or at least to something to look out for when buying a laser printer.

If you dampen a sheet of paper, you can determine the grain direction. When dampened, the waves will be along the grain, just like you see happening after you print with the laser printer. Paper will stretch and bend differently depending on the grain direction. The heat removes moisture causing the waves, the same as wetting the paper will create waves.

You could try placing your sheets in a book press after printing but I’m not sure that will get you to having no waves like the inkjet gives you. On lighter weight paper even a significantly more expensive digital press with a decurler can produce these waves.

 

[Tradidi]

If you dampen a sheet of paper, you can determine the grain direction. When dampened, the waves will be along the grain, just like you see happening after you print with the laser printer. Paper will stretch and bend differently depending on the grain direction. The heat removes moisture causing the waves, the same as wetting the paper will create waves.

You could try placing your sheets in a book press after printing but I’m not sure that will get you to having no waves like the inkjet gives you. On lighter weight paper even a significantly more expensive digital press with a decurler can produce these waves.

I understand all that. But if you wet 10 different sheets of paper, will the ups and downs of the waves be in exactly the same place for each sheet? That's what it seems to be with those text blocks in the OP. If these ups and downs were in different places, they would work against each other rather than in sync. That's the part I can't figure out, and that is what makes me wonder whether either the heat "hot-spots" or the rollers in the printer are perhaps shaping the waves to be all in the same place for each sheet.