Mug pressing - typical problems

[SteveHart]

What I've found out as a relative newbie is that mug pressing is not an exact science. This is what I've discovered - mostly the hard way, but also from reading on this forum.

Generally, I've found it better to go for a lower temperature and shorter time rather than increasing the temperature and time. Generally I'm pressing at 170c and 120 secs. Although I've recently gone down to 90secs. This is AFTER allowing the mug to heat up to 170c, which could be another two or three minutes.

Some advice on the internet says 200c for 5 minutes. This is WAY too hot and long. Although part of the 5 minutes may be heating up. But 200c I've found is way too hot.

If your temperature is too hot your black colour will look brown and other colours will start to look washed out. You can also tell if your temperature is too hot if there is a lot of burning/browning on the back of your mug paper

Fading at the base of the mug and towards the handle. This is caused by colder temperature at the base of the mug and towards the handle. It's harder to heat up the base because the base acts as a heat sink drawing out the temperature. Similarly with the handle. It's also near the edge of the mug blanket.

The temptation here is to increase the temperature. Don't. Best idea is to heat up the base of the mug before putting it in the press and/or put the mug as high in the press as possible. I heat up the base by holding it directly above the press as the press is heating up. But others have suggested warming it on a hot plate (cooker). I'm not sure what the solution for the handle issue is.

Colour bleeding, blurring after pressing and whilst cooling down. I've been getting this a lot recently. Just when I thought I had got on top of any printing problems. I think this is due to the mug still being hot and sublimation continuing after removal from the press. The ink spreads out and causes the blurring/bleeding. I get this particularly at the front of the mug (opposite the handle). I think it is linked to too high a temperature. On my press, I suspect that the area opposite the handle has a higher pressure on the mug than the sides. This increases the temperature towards the front.

The solution suggested by people on the forum to deal with bleeding is to quickly cool the mug by dunking in warm (not cold) water to stop the sublimation process. I haven't tried this yet. A bit scared of plunging a hot mug into water. But will give it a go and report back.

Inks: I started with sawgrass inks but the price is way too expensive. I tried out refillable inks from cityinkexpress and I can't really see any difference - so I'm happy.

Probably the most important thing I've learnt is lower temperature is best. Someone on the forum has stated that sublimation starts at about 150c, so pressing at 170c should be hot enough. Some people on the forum say 175c or 180c. At 180c I find I'm getting problems with being too hot. But, of course, that could be my set up. The rule of thumb is that if blacks look brown then it's too hot.

There is a sweet spot on the mug for your design that avoids most of the problems you will get. This is on the side away from the handle, front, top and bottom. This is where you might put a straightforward company logo type design. So if you tailor your designs to stay in this area it will make your life easier. But that is quite restrictive - and I tend not to.

[webtrekker]

The temptation here is to increase the temperature. Don't. Best idea is to heat up the base of the mug before putting it in the press and/or put the mug as high in the press as possible. I heat up the base by holding it directly above the press as the press is heating up. But others have suggested warming it on a hot plate (cooker). I'm not sure what the solution for the handle issue is.

I use 2 mug presses. The first is set at 110° C and 180 secs, the second is set at 180° C and 180 secs. I wrap my mug then place it in the first, cooler press. This pre-heats it to 110° C which is enough to warm the mug up without starting to sublimate the print.

When finished, I take it straight out and place it in the second press, set at 180° C, and cook it. I find this eliminates a lot of the heat-sink effects, but it's still not perfect (see below, where I mention ovens).

The solution suggested by people on the forum to deal with bleeding is to quickly cool the mug by dunking in warm (not cold) water to stop the sublimation process. I haven't tried this yet. A bit scared of plunging a hot mug into water. But will give it a go and report back.

I often, but not always, dunk my mugs. The water is above lukearm, quite hot really, but it still is cool enough to stop the sublimation. I dunk my mugs with the wrap ON, it's much easier to remove under water. I find dunking gives me nice, sharp prints.

Inks: I started with sawgrass inks but the price is way too expensive. I tried out refillable inks from cityinkexpress and I can't really see any difference - so I'm happy.

I use CIE inks and their paper, together with the ICC profile supplied by them and I too am very impressed. Blacks are always pure black. I use these inks in Ricoh SG3110DN printers.

Ok, now about these ovens .....................! I tend not to use my mug presses very often now, much preferring my halogen oven, which always gives me great, top-to-bottom, handle-to-handle sharp-edged prints. The oven totally eliminates the heat-sink issue as it heats up the whole mug together, over a period of 8 minutes (in my oven, others may vary). I still remove the silicone wrap when finished and dunk in hot water, as hot as my hands can stand. By increasing the time in the oven I can do up to 4 mugs at a time.

Hope that helps a bit.

[GoonerGary]

Now there's a man who knows how to join a forum. Research, learn, compile and share!

For your bleeding problems, remember that designs with tiny logos or black text require much less time than a design with full dark colours.

Your heat blanket doesn't last forever and can fail on one side or a certain section affecting your results.

The smart people use Inktec Sublinova Smart, professional ink with zero clogging issues and cheap!

In the colder winter months, try using an Andrew James cooking grill to pre warm the base of your mugs.

Buy the best mug, free from taper and dents.

Welcome to the forum.

[logobear]

good summary and great 1st post.

can pre heat bottoms of mugs with a spot of boiling water ...

pressure too high can cause issues of fuzz as the blanket and paper crinkles.

To avoid blurr / bleed, remove paper as soon as comes out of press.

Welcome!

[webtrekker]

I missed a very important point in my post above: for the best results ALWAYS use mugs with the best quality coatings. As the saying goes: 'Garbage In, Garbage Out!.'

[SteveHart]

Ok, now about these ovens .....................! I tend not to use my mug presses very often now, much preferring my halogen oven, which always gives me great, top-to-bottom, handle-to-handle sharp-edged prints. The oven totally eliminates the heat-sink issue as it heats up the whole mug together, over a period of 8 minutes (in my oven, others may vary). I still remove the silicone wrap when finished and dunk in hot water, as hot as my hands can stand. By increasing the time in the oven I can do up to 4 mugs at a time.

[MENTION=7061]webtrekker[/MENTION] I've experimented with halogen ovens and conventional ovens but had trouble with getting the temperature and timing right. I've also had trouble with less than perfect straight sides causing fading in the middle of the mug. What are your temperature settings on an oven? Do these settings change from a halogen to a conventional oven?

[webtrekker]

@webtrekker I've experimented with halogen ovens and conventional ovens but had trouble with getting the temperature and timing right. I've also had trouble with less than perfect straight sides causing fading in the middle of the mug. What are your temperature settings on an oven? Do these settings change from a halogen to a conventional oven?

I know what you mean by less than perfectly straight sides. I order Listawood's best AAA 11oz Durham mugs but even the the sides aren't always what you'd call perfect. So what I do is, if I have a wrap that covers the area opposite the handle, I check my mug with a straight-edged metal ruler against the light from a window, or my monitor screens, and make sure that area is not barreled or pincushioned.

As for temperature and time, I have a free-standing oven thermometer inside the glass bowl of the oven and when that reaches about 180° I pop my mug in for 8 minutes. I don't think timing is very critical, but 8 minutes seems to do me fine. The temperature dial on the oven is less than useless, but once you have it set using the thermometer you should never need to alter it.

[InkExpress]

Now there's a man who knows how to join a forum. Research, learn, compile and share!

Couldn't agree more! Great first post! Welcome (with open arms)

[wendyh]

Fading at the base of the mug and towards the handle. This is caused by colder temperature at the base of the mug and towards the handle. It's harder to heat up the base because the base acts as a heat sink drawing out the temperature. Similarly with the handle. It's also near the edge of the mug blanket.

I find warming the mug up first helps quite a bit. The first 2 mugs of a batch I warm up the base in hot water, then when a mug is printed and comes out I turn it upside down and place a cold mug on it to warm that one up ready for printing.

[webtrekker]

The thing I would really like to know is ...

We all seem to have problems where not every print is perfect. Personally, I won't send out anything unless it's 100%, however, I see companies producing hundreds, if not thousands, of mugs a week and they simply tape their wrap on, and either bung the mug in a press or use a silicone wrap and send dozens at a time through a conveyor oven.

The question is: How many of these are rejects, or do they just send them out regardless of quality? I find it hard to believe they don't have the same problems that I do.