White Edged on Aluminium sheets

[Cd1986]

Hi,

I'm wondering if anyone can help with a problem I'm having when printing on 0.5mm thick coated aluminium sheets?

The prints generally look great but when I lift the metal off the paper after pressing, the edges start to go white, as if cold air is getting under the coating at the sides and fading the ink or something. This only seems to happen with dark colours, mainly black. Settings and my method is as follows:

Printed on Truepic paper using a Ricoh SG3110
paper on the bottom of the press first, then the metal on top facing down (I have also tried the other way around)
Pressing at 190 deg c for 60 seconds, medium pressure
When the timer goes off, i remove the paper and metal, then pull the paper off straight away. I have also tried letting the metal cool on the paper (Which does help a bit).

If I increase temp/time, the print quality is reduced and the paper starts sticking to the metal.

I have attached an image to show the problem.

Thanks in advance!

[ATTACH=CONFIG]2889[/ATTACH]

[Scotty@BMS]

I'd personally press metal up with the transfer on top, increase the pressure and try 185 degrees for 75-80 seconds.

[Justin]

I always pre warm the panels a little which seems to help. I print all metal with the transfer down metal on top though.

[ArferMo]

most manufacturers recommend transfer on the bottom and let the heat go all the way through the metal down to the transfer.

[Cd1986]

Thanks for the replies.

When I put the metal in the press and close it, the temp goes down to 184 ish so that might be a problem. I also use baking paper on the top and bottom if that makes a difference.

i will have a play with temps and times tomorrow.

[Justin]

Temp. will drop if you're putting a cold blank in, same as with a mug. Shouldn't be a problem and temp should soon recover.

[Cd1986]

Just to update this, I tried pressing at 185 for 74 seconds and the image looks good. I then let the piece cool on the paper on my workbench but when i removed the heat tape, the area where the tape was suddenly went white (see image attached).

[ArtyGamer]

The white caused by the heat tape is pretty much a given as you're likely taking no chances with the paper moving, so putting the tape on pretty tightly... which means the gases can't get to the metal to sublimate the dye. It's like the old cartoon thing of Pink Panther standing against a wall while someone paints it, then he moves away and there's a panther-shaped space on the wall. This is just a tape-shaped space on your metal.

Personally speaking, I use a Ricoh 7100 with TruPix paper and an Adkins Studio Auto Clam Senior press with the paper on first, then the metal on top. I always sublimate at 200 degrees for 60 seconds. I haven't yet had a problem like yours. Looking at your initial attachment and how ragged the white edge is... I'd say that's more likely that the surface itself is mottled and perhaps exposing the untreated material below it so the dye can't actually be absorbed into the substrate as it's not present in those areas. May not be the case, but that's what it looks like to me... as though the metal was damaged in the cutting process and the coating was removed in tiny areas.

[Cd1986]

That's really helpful, thanks. I'll try and be careful with the tape.

it might be worth me trying a different metal then, if only to eliminate the problem. I'm currently using the aluminium sheets from BMS. I know they have a pretty good reputation so I assumed it would be okay but maybe that's the why their sheets are a little cheaper than most places. Is there a particular sheet that you would recommend?

They are being used for door plaques if that helps.

[ArtyGamer]

The only metal I've sublimated is the phone case backs, rather than metal sheets, but I always check them before pressing as the first batch I ever bought had the same issues you're experiencing so I sifted through all my unused blanks, picked out the ones which I thought had ragged cuts and tested them... they all had the white edges. Just to make sure, I then sublimated a few which appeared perfect to the eye and they came out fine. It's why I always go through my cases when I get a new batch and throw away any metal plates which are visibly ragged at the edge as well as any of the 3D cases which are even SLIGHTLY warped as the heat will warp them more (but that's for a different thread!).