DSF

I've just subbed pressed some glass coasters, and have been noticing the black not coming out consistent. The design that showed it most had some quite dense black in it. Of the four I made of that design, two of them turned out darker than the other two. The lighter blacks went into the reddy brown spectrum somewhat. Annoying if you are hoping for a set of four coasters.
My question is, does the press time or pressure need tweaking after it has been on for an hour or so? Does it shift a bit or 'settle'?
Also, does more time or more pressure help colour density? Or less? I'm using subli classic + paper and a Ricoh SG3110dn, a Stahls clamshell and I'm following the instructions from TTP, 4 mins at 200, medium pressure.
I would like dense blacks, or at least predictable blacks. Any advice?
I am using a silicon mat on the bottom platen, which gets very hot, would the fact that the paper contacts this v hot surface just before I close the press make any difference? It's only a couple of secs but it starts to steam and crinkle a bit. . Obviously when doing the first few pressings it's not so hot.
Thanks,
Jon

The quality of the glass coasters are not consistent - some of them are in fact quite shoddy (there is a thread on here already discussing this)
You have a good quality press, so I would expect it to be good with consistent and even temperature over time, with the thermostat doing its job.
The one thing I note is that you're using a Ricoh, which have different sublimation inks compared to Epsons, and 'cook' at a lower temperature, so would suggest backing your temperature off maybe 10 degees - am sure someone who prints which a Ricoh may give you a more accurate temperature suggestion.
Because you are printing a frosted glass rather than onto a pure white surface, your colours will be affected, and there's not much you can do about that, as to make a custom ICC for these would be tricky in terms of practicality of taking he measurements through the glass and for the cost of the amount of coasters you need to use.

Thanks Pisquee,
I read the thread about the glass coasters, it was that which led me to the clear ones from TTP that you use. I'll try backing off a bit on the temperature, 10 degrees as you suggest, thanks. I'm getting a feel for which colours work best and which types of design are best suited. Some trial and error is inevitable but I am trying to minimise it. Overall I'm pleased with how they turned out.
cheers,
Jon