Mimaki UCJV, cast vinyl, silvering effect after laminating

[yannb]

Hi,

We experience a silvering effect when laminating a cast vinyl print produced by the Mimaki UCJV with LUS170 inks. By silvering I mean that dark printed areas appear more greyish after laminating. When applying pressure like scratching with a fingernail the silvering effect is greatly diminished.

Currently tested are Orajet 3951 + Oraguard 293 and Grafityp AE38P with LAMX30. Tried temp from 40 to 60°C. (104 - 140°F). We notice however that 60°C it's better than at 40, but the silvering is not entirely gone. We have a customer however who's very picky about this.

Can anyone share some thoughts?

Request for more info is being sent to both the printer and media suppliers.

Regards,
Yann

 

[Solventinkjet]

As long as you are using heat assist it shouldn't have that effect. I don't have a lot of experience with heat assist. Can you go hotter?

 

[yannb]

As long as you are using heat assist it shouldn't have that effect. I don't have a lot of experience with heat assist. Can you go hotter?

Hi, we've redone a test and pressed the heating startup cycle on the laminator twice, and then it went to 80°C (176°F). Those laminated prints are better than those of 60°C. Again, the silvering not entirely gone. But.... the media supplier told us that heating too much would affect the laminate's adhesive power, and we don't want to risk that too.

 

[signman315]

What type of laminator? Does it have pre set pressure options or a wheel to manually adjust pressure as needed?. Older laminators don't have the wheel and as a result might be light on pressure if not calibrated regularly as the rollers dry up and contract from age. If you have a roller wheel to raise/lower the top roller then you can try increasing pressure while laminating until the incoming vinyl starts to wrinkle, then back off the pressure slightly to stop the wrinkling...that's the sweet spot, mark it on your machine with some tape as a quick reference. Also what size diameter rollers? Bigger rollers leave the laminate/substrate in the nip longer giving better results faster. Or if you have small rollers you can slow it down to add some time in the nip. Does the silvering go away after a few days? Most often the silvering does disappear after a few days....I UV print a lot of magnetic sheeting and laminate with dry erase with a heat assist, newer GFP and it silvers right off the laminator but is 100% gone in 24 hours.

 

[Asuma01]

Silvering generally goes away after a couple days.

 

[Broome Signs]

put the heat on 75 feed rate lowest setting
dont over pinch the rollers

remaing silvering will be gon by the next day

 

[lubo1972]

I think that UV print always will have silvering after laminate. Also glue doesn't stick very well on top of UV inks.