BC01 Oven - handful of mugs coming out with flaws

[garysub]

Just in case it helps any other forum members............................I have been messaging gazfocus for a week or more now as I also experienced a very similar problem. We have both been printing mugs over the last week or so (multiple suppliers/sizes) to see if we can eliminate the problem, which it now looks like we have. It looks like the problem comes from:

1.) Mugs not being perfectly straight (are any?)

2.) The paper not making good enough contact with the mug

It turns out that both gazfocus and I printed our transfers 3UP on an A4 sheet. I was using Truepix paper and he was using srace, which he cut down to be A4. In both instances we printed 3UP, so the paper was 210mm wide. I noticed that the A4 TruePix was Short Grain (i.e. the grain ran with the short edge), as a result the paper is more rigid when taped to the mug than if it was cut across the grain and folded with the grain. We have both been printing the opposite way around (i.e. printing 2UP on A4) for a week and the problem has been eliminated. I'm guessing the paper can "get into" the dips in the mug more easily if the grain follows around the mug. It's only quite a slight difference but it looks like it is enough to cause "a handful of problems" in an oven load of mugs. I'm guessing a similar thing might be possible with lighter papers, but I haven't tried that.

So if you print 3UP, get some mugs which are not as perfect as you might like, I'd suggest trying to print your transfers so you cut through the grain. Just to be clear this is really only an issue with printing mugs in an oven (as I guess the press would allow for this small difference more easily than a mug wrap) and only if the tension in your wraps is not sufficient to overcome the resistance from the paper. It looks like it can be a small but material difference between an oven load that's perfect every time and having a binned mug or two in a batch.

[GoonerGary]

Are you saying that you changed to printing 2 transfers in landscape format on an A4 sheet and that fixed it?

[gazfocus]

Are you saying that you changed to printing 2 transfers in landscape format on an A4 sheet and that fixed it?

I was the second half of this experiment and yes, printing 2 up landscape appears to have solved the problem but it’s down to which way the grain runs.

For example, we tried using Trupix Classic which is short grain (the grain running left to right on a portrait sheet). We switched to cutting down A3+ Srace to A4 sheets which again gave us Short grain, so printing landscape meant the mug sheets were short grain (top to bottom).

As an ultimate test, we bought some A4 packs of srace which came yesterday and they are long grain so can go back to printing 3up on an A4 sheet.

Never imagined the grain would make a difference but every mug we’ve printing since making sure the grain runs top to bottom of the mug sheets has been perfect.

[JMugs]

That is a combination of amazing and fascinating. Well done folks.
Janners

[socialgiraffe]

This is interesting and something I might look into replicating just to see.

But on another note, why are you using oven(s) for printing mugs when the printing width you are using is only 210mm?

Surely it would be quicker and cheaper to get a bank of mug presses. There are presses that will print a mug in 45 seconds so surely it would make sense?

[gazfocus]

This is interesting and something I might look into replicating just to see.

But on another note, why are you using oven(s) for printing mugs when the printing width you are using is only 210mm?

Surely it would be quicker and cheaper to get a bank of mug presses. There are presses that will print a mug in 45 seconds so surely it would make sense?

For us it comes down to both volume and print quality. We have found we get a much crisper print using ovens than presses. Also because we have three ovens on the go, we get about 144 mugs an hour printed. We’d need 12 mug presses to match that.

[GoonerGary]

I was the second half of this experiment and yes, printing 2 up landscape appears to have solved the problem but it’s down to which way the grain runs.

For example, we tried using Trupix Classic which is short grain (the grain running left to right on a portrait sheet). We switched to cutting down A3+ Srace to A4 sheets which again gave us Short grain, so printing landscape meant the mug sheets were short grain (top to bottom).

As an ultimate test, we bought some A4 packs of srace which came yesterday and they are long grain so can go back to printing 3up on an A4 sheet.

Never imagined the grain would make a difference but every mug we’ve printing since making sure the grain runs top to bottom of the mug sheets has been perfect.

I didn't chime in earlier because there's too many Garys on this thread. But I've got the same oven, same papers, 10oz Orca mugs, but I reckon that my wraps are tighter than those cheap green ones you use.

I wrap super tight, but I would get the odd mug which was lighter on one side when printing black text. I had a batch from Neil Bros AAA, which were badly tapered. Took a bit of arguing mind you to convince them. But since then, I do the rocking test on a flat table and discard those mugs. I'm more relaxed about testing now, as it's quicker to reprint the mug.

I print a little wider on the mug, so I always print two transfers landscape. Currently back to using TruPix A4. When you are wrapping a mug super tight, you'll know when your mug is tapered, sometimes I'll chance my arm. But I reckon that a bad mug has more influence when one side goes wrong than the texture of the paper. I only print landscape. I don't know if batches of paper get cut down differently though?

I was using Inkexperts paper for a while who cut down their paper, so I don't know if they pay attention to grain direction or not. I will keep an eye on this because I'm using TruPix at the moment. If any bad sides come up again, I'll do my rocking test after printing. I've had to increase my oven times by 3 minutes in recent months probably down to using Trupix, so ink release may be an issue too when swapping papers all the time.

[garysub]

The same reason here, quality and volume. I can have one guy/girl operating two large lab ovens, at around 100+ mugs an hour with some time to spare. That means we can run for 10 hours a day at Christmas which would be exhausting (and irritating - all that beeping!) for that long. No elements to replace, no problems with fading off near the handle, just much prefer the consistency from the ovens.

[garysub]

This is interesting and something I might look into replicating just to see.

But on another note, why are you using oven(s) for printing mugs when the printing width you are using is only 210mm?

Surely it would be quicker and cheaper to get a bank of mug presses. There are presses that will print a mug in 45 seconds so surely it would make sense?

The same reason here, quality and volume. I can have one guy/girl operating two large lab ovens, at around 100+ mugs an hour with some time to spare. That means we can run for 10 hours a day at Christmas which would be exhausting (and irritating - all that beeping!) for that long. No elements to replace, no problems with fading off near the handle, just much prefer the consistency from the ovens.

[garysub]

I didn't chime in earlier because there's too many Garys on this thread. But I've got the same oven, same papers, 10oz Orca mugs, but I reckon that my wraps are tighter than those cheap green ones you use.

I wrap super tight, but I would get the odd mug which was lighter on one side when printing black text. I had a batch from Neil Bros AAA, which were badly tapered. Took a bit of arguing mind you to convince them. But since then, I do the rocking test on a flat table and discard those mugs. I'm more relaxed about testing now, as it's quicker to reprint the mug.

I print a little wider on the mug, so I always print two transfers landscape. Currently back to using TruPix A4. When you are wrapping a mug super tight, you'll know when your mug is tapered, sometimes I'll chance my arm. But I reckon that a bad mug has more influence when one side goes wrong than the texture of the paper. I only print landscape. I don't know if batches of paper get cut down differently though?

I was using Inkexperts paper for a while who cut down their paper, so I don't know if they pay attention to grain direction or not. I will keep an eye on this because I'm using TruPix at the moment. If any bad sides come up again, I'll do my rocking test after printing. I've had to increase my oven times by 3 minutes in recent months probably down to using Trupix, so ink release may be an issue too when swapping papers all the time.

I ordinarily print the 10oz Orca mugs from Neil Brothers and agree you need to wrap them super tight!