General informations about Riso and multicolour printing

[benoitv]

Hello,

I just bought a used RISO RP3700 with a low number of copies (approx 400k) in order to print limited editions of graphic design books.

I know the limitation of the machine, mainly about the available colours and the relatively rough screen.

I have several questions about mulitcolour printing with these machines.

-First of all, the RISO I bought doesn't come with a RIP, would you recommend to use one for what I plan to do? I'll print mostly text and spot colours, but may need to print BW photography too. I'm assuming the different raster / screening options in the RIP are definitely something i'm gonna need, what would you suggest?

- So far we only have one black drum, but intend to buy quite a few colour drums (second hand because of the price) in order to be able to print spot colours.
I was wondering if it was possible to "convert" a certain colour drum (blue for instance) into another colour (let's say red) by running a few hundred sheets with a different ink cartridge, or cleaning it, or any other method. Or is it impossible, meaning that if a drum has been used once with a certain colour, it has to be the same for its entire lifespan.

- We are located in Paris, France, and may be looking for a parts dealer as we intend to do the maintenance ourselves. Does any of you know a riso parts reseller in western europe?


Thanks a lot for your precious advice,

Ben

[joelsa12]

I really doubt that you will need the RIP. With the embedded Rip you can still change the LPI and the Angle of the dots in a screen. I do not think that the other RIP is a must. The thing that you will have to be concerned with is dot gain. When the Riso puts down a dot of ink it will spread out(dot gain) as the ink is absorbed into the paper. It may take you tinkering with your photos untill the come out like you would like. You can change the ink drums. In tesk mode there is a ink drainage mode that will deplete the drum of its ink. Then you can fill it up with the new color. There really is not a limited amount of colors anymore. I believe that Riso has like 85 colors now. Go to their website and find the color chart under the print drum section. The main issue that you will run into is that a Riso is will run things at plus or minus a mm. That means with each color pass your image could move up to a mm up or down. Make sure that the second paper feed(clean timing rollers, and a good load spring) is up to par before you start your project to combat this. Also the slow the machine runs the better chance you will have of not having any image shift. I would try using the embedded computer interface first, before you get a RIP. I have two if you decide to go that route. Good luck and enjoy your RP3700 one of my favorite Riso's. I have a few in the field that I work on with close to 13 million impressions on them.

[benoitv]

Thanks for your answer!

You're right RISO has quite a lot of different colors now... But my secret plan is to try to print CMYK files, or something quite close to CMYK (I'd make a custom separation and profile using profilemaker software). So the question is, in these 80 or so different colours, which ones should I pick up to have the best possible colour gamut?

Benoit

[joelsa12]

I have seen this done before. I worked for a Riso dealer for a long time. At a show once they were showing off christmas cards with a scene with Santa on them. They were 4 color process and they looked very nice. I do not doubt that you will be able to acomplish this, but you will have some waste when the reistration is off. I have not a clue of what colors they used. Good luck and let me know when you get these done I would love to see one either on line or you could mail me one. If you need any service help I can talk you through it via email. I have a mind that takes pictures. I have fixed Risos in Africa over email and Europe. Good luck.

[benoitv]

I'll make sure to keep you informed of our progress.

And yes, some help fixing it would definitely be great in case of problem, i'll contact you in case we need your help!


Ben

[pepper38_cnd]

Thanks for your answer!

You're right RISO has quite a lot of different colors now... But my secret plan is to try to print CMYK files, or something quite close to CMYK (I'd make a custom separation and profile using profilemaker software). So the question is, in these 80 or so different colours, which ones should I pick up to have the best possible colour gamut?

Benoit

Your plan to print CYMK would only work if the inks were translucent, and to the best of my knowlege they are not, so the only color you will see is the one on top.

[RRodgers]

One thing about doing multi color printing on a Riso that some people forget is YOU HAVE TO SLOW THE MACHINE DOWN! Ya can't run it at full speed and expect the registration to hold.
GL and keep us in the know.

[jmp]

Not sure if you've seen this already, but here is a blog documenting a couple of experiments with 4 color riso printing: Guild of Duplicators
if you go back a couple of pages to November 2009 it looks like they got some pretty nice results with yellow, red, blue, and black, with red and blue tinted at 80%.

I'm hoping to do some similar experiments in the coming month or two and will also share any results/ tips.

[pttrnlanguage]

Re: General informations about Riso and multicolour printing

Bummer that that blog is down.

[Joe Stringer]

Re: General informations about Riso and multicolour printing

yes realy sad. would like to see that blog. maybe they moved?