Mug Printing problem - image fading

[Justin]

Not had this problem for a while and can usually solve it but this is driving me blooming crazy

Printing mugs with an image on the front and on the back. Back image prints fine, front image is ok except for the bottom 1/3 which is streaky faded.

I usually increase pressure, make sure paper is on properly and all the other usual solutions but 7 mugs in a row all ruined. I've decreased pressure, put tape along the edges, just can't suss it. Heat press had a new blanket not long back so surely it can't be that? I've even tried adjusting the height of the mug in the press incase the pressure was uneven.

[Lorcan]

Maybe the mugs aren't parallel? Put a straight edge on one...

[Justin]

As close to perfect as I've seen

[Lorcan]

Maybe they are not evenly coated? Press one upside down to see if it's the mugs or the press.

[Kaz]

I've had that with a few mugs aswell, I turn them half way through the process and it seems to work

[Justin]

OK, printed one upside down and problem remained, exact same area. As I say, mugs seem very straight. Could be a coating issue but identical on 8 mugs?

[Andrew]

Images of the mug would help. Even the design that you are printing if you don't have a picture available. Don't think the coating would be the problem. Sounds like not enough heat getting through to me. What time and temp? Is it a bold/dark colour which is diferent to the part printing okay? Are the lines even and paralell or just streaky patches? If they are even it would be the lack of heat and as you seem to reckon the mugs are good and straight then pressure and temp is one of the other typical problems. The joys of sublimation.

[Justin]

The joys of sublimation.

Yes indeed!

It does look like a lack of heat but having rotated the mug around this would seem strange. Everything's been working well for the last couple of dozen mugs.

Attached a lousy photo, best I can do at this time of night. It makes the problem look worse but you can see what I mean at the bottom of the photo.

[JSR]

Do you have a mug wrap at all? If so, do one in an oven and if it comes out fine then you know it's not the mug.

Is the base of the mug uneven (thicker on one side than the other?). The base always takes longer to heat up than the rest of the mug because it acts like a heat-sink. Who's mugs are they? (Just grasping at straws.)

Is the print on the paper okay? The paper hasn't been left exposed to the elements or got wet or anything? (More straw grasping.)

Hope you figure it out.

[Andrew]

They are the lines of the heating element that runs through the silicon wrap. Not enough heat is dispersing evenly to get an even print. Try increasing the pressure slightly so it is firm and also put the temp to 205c. You can drop it down by 5c if it helps and then find a decent level. I have in the past printed mugs so that the base is facing up as heat rises and that part takes more heating.

If this doesn't help you might want to check that the sides of the mugs are paralell. I know you said they are straight but measure the diameter of the top and bottom to check for a taper.