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Justin
09-06-2010, 10:18 PM
Not had this problem for a while and can usually solve it but this is driving me blooming crazy :x :x :x

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
09-06-2010, 10:25 PM
Maybe the mugs aren't parallel? Put a straight edge on one...

Justin
09-06-2010, 10:28 PM
As close to perfect as I've seen :(

Lorcan
09-06-2010, 11:21 PM
Maybe they are not evenly coated? Press one upside down to see if it's the mugs or the press.

Kaz
09-06-2010, 11:31 PM
I've had that with a few mugs aswell, I turn them half way through the process and it seems to work

Justin
09-06-2010, 11:32 PM
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
09-06-2010, 11:47 PM
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
10-06-2010, 12:06 AM
The joys of sublimation.

Yes indeed! :cry:

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
10-06-2010, 12:26 AM
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
10-06-2010, 12:53 AM
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.

Justin
10-06-2010, 11:24 PM
OK, raised temp to 205c and time to 195 secs. Printed another 6 mugs and they look fine. Next mug out has similar problem but you can actually see the shape of the element in the photograph! I guess this could be an element problem. Very bad timing, why is it always when you have a decent size order that has to be out quickly?! :cry:

Justin
11-06-2010, 10:35 PM
Another kick in the teeth. A friend lent me a brand new 4 in 1 press to help get the mug order out.....it has 2 mug elements, one for an 11oz mug and the other for much smaller....neither will work with my 10oz mugs! :cry:
Never been a fan of these presses but was looking forward to having a go.

bms
11-06-2010, 11:10 PM
neither will work with my 10oz mugs
Don't follow why this would be the case - both 11oz mugs and 10oz mugs, normally, are 80mm in diameter so an "11oz" blanket (which is another name for the standard mug blanket) will print a variety of mugs which are around 80mm in diameter.

How are you pressing the mugs Justin - putting a mug in when the display is reading 180 degrees, or whatever you have the heat set to (after taking out a printed mug)? If some are printing fine and then you get a rogue one then this is strange, especially with the lines showing as per the image. Do you have a sheet of the silicon wrap available - the red rubberised material? You could wrap the mug with this before putting it into the press and this will help to spread the heat more evenly over the mug surface.

Justin
11-06-2010, 11:15 PM
The combo press doesn't adjust enough to be suffucuently tight for 10oz mugs.

I wait for the press to reach full temp beforte putting mugs in. All mugs are coming out the same now with the lines. Don't have any silicon wrap or I could use it in the combo press.

Just reduced the pressure down a fair bit and tried another, print came out ok but definate element shape lines showing.

bms
12-06-2010, 09:51 AM
wait for the press to reach full temp beforte putting mugs in
When heating up any mug press that goes all the way to 180-200 degrees you really ought to put a mug in the press (one which you re-use continuously for this purpose). This ensures the blanket doesn't get overly hot during the warm up process (and potentially burn out). Once the press has reached 180 degrees with the mug in place then remove it and put in your mug for printing - the temp will drop and then gradually heat up again.

The original mug should be put back in the press during cool down as well as warm up. Doesn't help solve this problem necessarily but helps to prolong the life of a blanket.

The element in a the mug press is a continuous loop - the power leads go in and come out at the same point, so the blanket should work (through a continuous feed of heating element - a bit like a warming blanket for beds, but much more tightly woven) or not work at all if the element is broken. Do you have an infra red thermometer to test the temp of the blanket at different points?

Justin
12-06-2010, 04:02 PM
Yes, I always put a plain mug in during warm up and inbetween presses, sorry I must have missunderstood your question.

I tested it last week with a therm. And it was fine, will have to try it again.

Justin
12-06-2010, 06:52 PM
The element's definitely working but I'll check the temp. all round. As I mentioned, the outline of the element is imprinting onto the image similar to an old kettle element shape so it's certainly working!

Justin
08-07-2010, 08:29 PM
Quick update on this problem.

Temp. checked on heat blanket, all seemed pretty much ok. New blanket fitted anyway, made no difference. Tried 2 different brands of paper, different temps/pressures/height in the press/time and so on. Nothing stopped the problem. Tried a different mug supplier and hey presto, the problem dissapears, 36 mugs printed perfectly. Went back to other suppliers mugs and problem immediately transpires. Went back and forth just to make sure.

Been in touch with supplier regarding what I assume must be faulty mugs or at least a fault in the coating. I've had to send them printed and unprinted mugs form the same batch along with printed/unprinted papers from 2 suppliers. They're now carrying out their own tests!

Will update when I hear back from them.

Andrew
09-07-2010, 09:57 AM
That's a strange problem to figure out on the mugs. If they do print but show the heat element lines and the others print fine then it sounds like heat dispersal problem or the coating scorching slightly under direst heat. Sounds a fun problem for someone to work out.

Justin
09-07-2010, 07:57 PM
Fun problem that's cost me a fair whack in wasted time and materials! lol. :cry: