blacks coming out brown

[bfbs]

I am using a Mug press machine GS-201T - 220v - 350w+350w
a Ricoh SG2100N Aficio and 11oz white ceramic mugs.

i have been using these machines for a few months now and have seemed to have a lot of different problems with them. however i have been trying to print out several different orders/designs that have black in and although i will do tests on one design and find the perfect settings for that one, when i then try to do another design with black in it will come out brown/blurred? so i find myself having to do this for each design to get it to come out right which means i am losing a lot of mugs with a few tests each time.
However i have a few designs at the moment that whatever i seem to do it will just not come out right??

The settings that have worked well for most designs are 180 for 120 seconds with medium pressure or around this. i started at 180 for 3 mins and have worked down with time and pressures and can normally find one to suit but i am struggling now.

the only thing i can think is that we have been changing mug supplier due to a high number of orders when our suppliers have been all out of stock so having to find different ones. however sometimes it is the same mug that is used and still does not seem to work.

we have tried heating the bottom of the mug first by pour boiling water in to fill around 1 inch and that worked for a while but still ends up not looking right!

why would this not work for all designs? any ideas??

[Adrian B]

Your black ink is burning. Try lowering the temperature to 170 Deg. Reduce temperature to a point where the burning black is not an issue. Increase time if required to around 140 seconds. Dark images that go from the top to bottom of mugs can be problematic often due to non square sides. Consider a 5mm unprinted border top and bottom.

Some people like webtrekker advocate pre pressing of mug at about 140 deg* in a second press to allow heat to be properly maintained at the required temperature in the base of a mug. The base is the thickest, densest area on many ceramic mugs is often difficult to get enough heat to be retained in this area compared to the much thinner sides.

* Correction - as you can read in webtrekker's reply the temp that he uses is actually 110 degrees.

[webtrekker]

Some people like webtrekker advocate pre pressing of mug at about 140 deg in a second press to allow heat to be properly maintained at the required temperature in the base of a mug. The base is the thickest, densest area on many ceramic mugs is often difficult to get enough heat to be retained in this area compared to the much thinner sides.

Thanks for adding that Adrian.

I actually pre-press the mug at 110 deg (140 is a bit too high) with the print already taped in place. I do this for 240 secs. I then transfer mug+print to my second press which is at 180 deg C for 180 secs. Never had one bad print since using this method and my blacks are black, even with non-Sawgrass inks.

[webtrekker]

I should also add that I let my mugs air-cool and still have nice, sharp images on them. My theory is this ..

A lot of people seem to have faint lines or slight banding in their printouts and it seems very difficult to get rid of this in most cases. By allowing th mugs to cool down naturally, instead of stopping the sublimation process dead in its tracks by water cooling, I find that any small occurrences of lines or banding blend into the rest of the image as the polymer pores have longer to close.

That's my theory anyway, and probably a million miles off-track, but I do know that it seems to work for me. :biggrin:

[mrs maggot]

worth also typing in "blacks coming out brown" into the search on here, as there are quite a lot of posts on it, with answers

[bfbs]

okay will try at the lower temperature!

i also just let my mugs cool down naturally. also i have been searching on this for about two weeks looking at different posts and have tried everything i have seen, this is how i managed to find the perfect settings when doing other designs. it just seems although that setting works for one design it doesn't for another...

example - at the beginning of last week i did an order of 288 mugs, which had a dark green and black Kawasaki design on them and did a few test to make sure the settings were right then once found i got all the mugs done. i then move on to the next order of 200 mugs which have a similar design however is mostly black with circle of colour and everything i try with these just come out brown.. but i will try the suggestion above. Thankyou!

[Justin]

Always remember to check the similar threads box at the top once you've posted:-)

[paul 44]

I had that problem on a few of mine, it was a case of trial and error really, once you get the correct setting jot it down on paper then you will know for the future.
My mugs sit in the press at 392f and the time is set to 60 seconds for the main press, I place the mug in the press and let the temp drop until it heats back up, when the mug press is at idling temp i will then press the mug at press temp, overall its like a 2-3 minute press time and when the mug comes out of the press I bang it straight into cold water and comes out great everytime.
You probably know all this already but thought i'd just say what I do to press my mugs (not a bad mug count there, must have kept you busy for a while!)