BC01 Oven - handful of mugs coming out with flaws

[gazfocus]

So as some of you may remember, a while back I ditched my multiple freesub double mug presses for a BC01 oven.

I have always done our mugs at 160 degrees for 23 minutes (with 20 mugs in the oven), but the text doesn't come out as sharp as I'd like it. So, I have tried reducing the time to 21 minutes and the text comes out nice and crisp and looks so much nicer than anything that ever came from the mug presses.

My issue is that if I have a design that has a solid black box for example, 18 of the 20 mugs will bake perfect, but 2 will come out with a green patch in the black box (or very occasionally a mottled grey as if it's not been in long enough).

Does anyone know what might be causing the green? Is it too low a temperature or not enough time? If I do them for 23 minutes I don't get the green but the text is not crisp.

Would really appreciate any feedback/tips.

[gazfocus]

Ok so now I’m getting this on mugs that are black text only. I’ve attached a photo. On a mug press I would say this was a pressure issue but the silicone wraps are tight and only had this since dropping the temperature.

any help would be very much appreciated.

[GoonerGary]

The mug isn't straight. When you place the mug on its side, you will hear them rocking about because they are not perfectly straight. Where did you buy them?

[gazfocus]

The mug isn't straight. When you place the mug on its side, you will hear them rocking about because they are not perfectly straight. Where did you buy them?

You're correct - never would have thought to check, but you're right...there's a dip in the mug where the flawed print is.

Any way to combat it?

They're from Neil Brothers.

[GoonerGary]

Use thinner paper to help hug around the dips.
Reject mugs.
Complain to retailer about the shape of the mugs. Every mug should be printable...why should we foot the bill?

[gazfocus]

Use thinner paper to help hug around the dips.
Reject mugs.
Complain to retailer about the shape of the mugs. Every mug should be printable...why should we foot the bill?

The paper we use is srace. We have used the same paper in the oven since we first bought the oven and the same mugs and have never had these issues. I have also checked some of the mugs that have printed fine and they too have similar dips yet have printed ok so I'm really confused by this.

I'm left wondering whether the silicone wraps have stretched too much and therefore need replacing already...I don't know.

I've emailed Neil Brothers about it and their reply was to just buy their Grade AAA mugs instead of the Grade AA mugs but at £400 per pallet extra, I don't see that as an acceptable response.

Out of 300 mugs printed today we have binned about 60 which is really annoying.

One thought I had was I wonder if putting another piece of normal printer paper in between the wrap and the mug would help to create more pressure on the mug.

[GoonerGary]

Are you re-using the wraps when they are still warm from the previous print run? Let them go cold again.

Some of your wraps may have stretched? If I get a misprint and the mug seemed fine, I would put a big red X on the wrap. If it happens again, the wrap gets binned.

The AAA mugs still wobble on a flat desk.

[gazfocus]

Are you re-using the wraps when they are still warm from the previous print run? Let them go cold again.

Some of your wraps may have stretched? If I get a misprint and the mug seemed fine, I would put a big red X on the wrap. If it happens again, the wrap gets binned.

The AAA mugs still wobble on a flat desk.

No, we don’t use the wraps while they’re warm, we let them cool to room temperature before reusing them.

How do you keep track of which mugs come from which wraps out of interest?

do you think the heat shrink wrap stuff would work better?

[gazfocus]

Are you re-using the wraps when they are still warm from the previous print run? Let them go cold again.

Some of your wraps may have stretched? If I get a misprint and the mug seemed fine, I would put a big red X on the wrap. If it happens again, the wrap gets binned.

The AAA mugs still wobble on a flat desk.

What mugs do you use out of interest?

[GoonerGary]

AAA Orca.

I don't like heat shrink.