how big a learning curve is 4 col process?

[Glenn Sharp]

Dermot,

In simple terms I think you are about right…

I think the biggest learning curve would be understanding separations and halftones etc if you were going to produce your own artworks, if you are going to buy them in obviously that wouldn’t be a problem.

We dabbled a bit printing onto correx and got some pretty decent results from the off…….the main problem was stopping the screen from drying in using solvent inks …..we looked into UV but that would have involved more expenditure and it wasn’t really for us

I think anyone with a decent amount of experience would be able to make the move into process without too many problems

[Dermot Howard]

Cheers Glen.
We have the gear and we have some Local Elections coming up shortly here, so there is some biz out there. And if all I have to do is pay attention to the detail, I may chance it.

Anyone know where i would get the films over here in ireland

[Mark Latchford]

Dermot if it is all new to you 4 colour process screen printing, when having your film seperations done I would go for concentric lines instead of dots as this eliminates the moire effect you can quite easily get if you haven’t done this before and is a lot more user friendly. Registration is the most important part of 4 col work. Also when printing always print in the same direction because if you don’t your registration will move about.

[Dermot Howard]

Hi Lads.
I have been looking into going ahead with the 4 colour and think I will try it. The only thing that that I would be of concern to me is my exposure unit. It is a home made job witch works perfect for the solids I usually do but just not to sure about getting the detail I need for process. It has 4 Philips HRP 125w Bulbs in the base of it. The table size is 2.1 x 1.4 with an effective exposure area of 1.7 x 1.0. there is no vacuum bed on it, I usually place a thick foam mattress over the positive and then put plenty of weight on top of the foam, works fine for the solids and I have got some good detail from it, but just unsure. On the up side, all it will cost to try is time and some emulsion. What do you think?
I have noticed that a good fresh emulsion is also most important and a screen mesh of 120??

Has anyone looked at this on line course http://www.worldofprint.co.uk/ ? what do you make of it?

[Glenn Sharp]

Hi Dermot

I wouldn’t put you off trying it but I’d be surprised if you got good, consistent results without using a vacuum

I suppose it depends on what size dots you are printing onto what substrate and with which inks to a certain extent aswell.

The accuracy of your positives is really important to successful prints as is the quality of your stencils…..if either of these are not good enough you will never achieve good results

Is there a local screen printer near to you that you could ask for some old posis to give it ago?

What kind of results are you looking for…….what exactly will you be printing?

[Dermot Howard]

The vacuum is a bit of an issue, you have a good idea about the old possis to give it a try. I can get the screens exposed but I am looking at a cost of €90 for a 1.2 x1.8 screen witch I will get 2 possis on.

I will be printing Election signs on to corri-board. As they would be up on poles I don’t think the results would have to be 100% I have attached 2 pic of an old sign a client brought into me. The pic of the full sign is taken at a distance of about 2.5mt and the close up at a distance of .6mt

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[David Rowland]

is that one you have done or a sample someone’s asked you to copy?

the important is getting the dots right, we found that using bigger dots (or elipses) worked well and as your not going for 100% colour perfection then your setup is likely to be okay.

What I found is to stop highlights from creating small dots, so where a 5% grey would be, I would make this 0% grey etc. So everything under 10% of colour is actually solid and not a dot.

Long time since I been doing 4 col proc, but Sericol Tricromatic ink in PY is what we used but not on Corex.

[Dermot Howard]

HI Dave.
The pic is a sample a client brought in. it looks ok from the distance and if i can get that quality i would be happy, I dont think it is 100% what would you give it from the pic?

I get what you are saying in relation to not using less than 10% or any colour, i would be looking for less detail and there fore less accuracy in relation to dots

Any printing i do i usually use the sericol range, just have not used the Tricromatic inks. Millers are the suppliers here.

[John Gregson]

Hi Dermot,
Give it a go, but i’d be surprised if you get any usable prints with the set up you have. For halftone work your screens have to be perfect and printing onto correx would be a nightmare as I don’t know how you would achieve the registration and the static would be a huge problem.

To be honest after setting four screens up, probably around the £100 mark, and printing 4 colours your prices wouldn’t compete with digital. Save yourself the time, money and hassle, farm it out to a digi printer.

Cheers John

[Matic Serbelj]

4 color process printing with screens is very hard. not only you have to have film-s made very good, you have to expose the screens at different angles because every color has to be printed at different angle so the picture comes out good. You will need a vacuum table. the screens have to be very good tightened and stay away from 0-5% dots, maybe more. In every printing technique there is dot gain .. in screen printing theres alot more dot gain than in offset so the 40% dots would turn out 55% or maybe 60%. You have to know what dot gain youre having so you can play around with curves to lower the dots beforehand. So if you want to print 50% your image in photoshop should have a 35% big dot so that in the print it comes out 50%. Hm .. we use hard squeeges for printing detail and you mesh should be 120+ threads.

+1 on what John said:
"printing 4 colours your prices wouldn’t compete with digital. Save yourself the time, money and hassle, farm it out to a digi printer. "