Why Dryoffset printing need to apply negative trap??

[Groovy HO]

Hi All,

Please correct me if I have anything wrong as I am a beginner in printing field .

Dryoffset haven't involved any water to divide the ink for each other. If we don't apply a show through area between each of them. they may spread to other colour.
So we need to use negative trap. Is that right?

Why don't we use offset printing instead of dryoffset printing? is there any advantages for this printing?

Thanks for all your help!!

 

[Deleted member 16349]

Hi All,

Please correct me if I have anything wrong as I am a beginner in printing field .

Dryoffset haven't involved any water to divide the ink for each other. If we don't apply a show through area between each of them. they may spread to other colour.
So we need to use negative trap. Is that right?

Why don't we use offset printing instead of dryoffset printing? is there any advantages for this printing?

Thanks for all your help!!

Just to clarify the terms. Dry offset is a process that uses flexo like plates which have a raised ink surface that contacts a blanket. A more conventional ink fountain and roller train are used to ink the raised plate.

You might be talking about Waterless offset which uses a flat plate but one that has a silicone surface in areas that do not accept ink in the non image areas. Water is of course not needed in this process.

Can you confirm exactly what process you are using and what you are printing might also be of help?

 

[Groovy HO]

I am looking for the printing process which print the Aluminium Can Product like Coke Cola, Pepsi......

And they are using Dryoffset Printing process, so which type of process they are using?

 

[Deleted member 16349]

I am looking for the printing process which print the Aluminium Can Product like Coke Cola, Pepsi......

And they are using Dryoffset Printing process, so which type of process they are using?

OK, Can or container printing is probably using Dry offset and I am guessing that it is with a common blanket where all inks from each station are printed on the same blanket.

For a common blanket press, one is not supposed to overprint inks. It sometimes is done but it is not recommended because it does not work. The reason it is not recommended is that there is a systemic problem with printing one ink on another onto the blanket and then onto the can or container. There can be a lot of failure of the wet trapping (back trapping) and inks will mix and contaminate the roller train and ink fountain. Maybe this is the reason why there is a need for some clearance between inks in the image you are talking about.

If there was not a common blanket, as with CI flexo, then one can overprint the inks. Normal wet trapping rules would apply.

 

[Groovy HO]

Thanks for explanation. What is the advantages for Dry Offset printing? Why don't we use the Offset or Flexo for printing Can and Container Product?

 

[Deleted member 16349]

Thanks for explanation. What is the advantages for Dry Offset printing? Why don't we use the Offset or Flexo for printing Can and Container Product?

My first thought would be the problem of registering the separate images from multiple blankets onto a can or container that is mounted on a free wheeling mandrel. The mandrels would have to be driven in a very positive way via gears or servo drive plus there would have to be no slippage of the can or container on the mandrel. That would make a very expensive machine.

With a common blanket press, it is quite easy to register the images to the blanker. The drawback is that one can not overprint with CMYK process inks but must use all spot colours.

So it is not so much about offset or flexo, but it is about the common blanket. Actually Dry offset is really a kind of "flexo offset" but with a roller train and not an anilox roller inker.

Inkjet printing of cans might be the future. Some are done already but it is slower. But no plates are required and much fewer inks because one could over print and use CMYK + so set up time would be quicker.

 

[Alois Senefelder]

Printing on Metal

Printing on Metal

Gentlemen,


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