Stippled/waves effect on yellow colour.

[Anne_83]

I'm sublimating small 8x6 inch aluminium sheets on my Stahls Maxx 38x38cm heat press. Everything looks great, except I've noticed that the yellow colours appear to have a stippled/waves type texture to them. Every other colour is fine.
Settings are as follows: 180c for 70 secs, medium pressure.
I also sublimate mousepads and mugs using the same inks and paper but have only ever encountered this problem when sublimating (white coated) aluminium sheets.
Does anyone know what might be causing this, please?

[webtrekker]

What pressure are you using? I get best results on aluminium using very light pressure, so light in fact that it's virtually just the weight of the top platen providing the pressure.

I also press between sheets of copy paper or kitchen roll to reduce the effects of moisture, which usually appears as a 'marbled' effect.

[Anne_83]

Thank you for your reply. I'm also using a very light pressure and copy paper (two sheets top and bottom). Since my previous post I've taken a closer look at my actual print outs (from Sawgrass SG400) and have discovered that this effect is actually many small dark dots. It's definitely not a dust issue as I have printed the same image a few times at the dots appear in the exact same place. I've attached a close-up of a scan of the printed page. The image shows what should be a white square and a yellow square. In Photoshop, zooming right up close to the original image shows pure white and yellow with zero dots.

After a little bit of googling I'm thinking this is some kind of "dither" setting, but I don't really understand how that works! I know that in my printer settings dither is set to "automatic" at the moment.

Any advice would be appreciated. I suspect this problem has always been going on when I print mugs, but because the images are smaller it is almost unnoticeable on them, but on larger metal prints it is very clear to see.


sample.jpg

[webtrekker]

What model of printer are you using? Dithering can be a problem on printers with only 4 colours (CMYK). Is the resolution of your original image adequate, ie 300dpi or more without scaling?

[Anne_83]

Printer is a 4-ink Sawgrass SG400. My printer resolution is set to 600 dpi. My original images are all done at 300 dpi. I'm also printing via Photoshop.