Spot UV - offline with screen printing

[barryk]

I run an offset printing company and I would like to do some testing with offline Spot UV on printed offset work (utilizing screen printing).

I have on offline UV roller coater so I thought I could make use of the conveyor and lamps for the UV.

Unfortunately I know nothing about screen printing and even ran a local ad for someone with experience to show me the ropes but no luck. I am looking for insights into the following:
- type of UV clear ink to get (vicscosity of ink to use?)
- type of screen mesh count to work with
- anything else to be of help

I was out one day and bought a screen from a local store and tried with my own coating (for use in roller coater) but had no luck.

Any help/direction would be appreciated.

 

[donp]

My first suggestion would be to get an introductory book out of the library so you can learn how to make a stencil, (stretch and coat a screen with emulsion, expose with a film positive, wash out image with water, blockout and tape remainder of the screen).

You'll need to buy a gallon of litho overprint clear. There are many different brands for different applications. Biggest kid on the block is Nazdar, but there are others. They would be able to recommend the best product. Viscosity depends on the production equipment - we run mostly on a cylinder press and prefer slightly thinner ink, but some will print right out of the can. (Buy some reducer when you buy the ink)

Screen mesh - anywhere from 305 and up for overprint clear. We use mostly 355 plain weave fabric, finer than that is pretty pricey.

 

[barryk]

Hi Don thanks for the tips.

Well I bought a 380 mesh screen as well as some Nazdar overprint clear. I also made a vacuum frame to hold the stock down. The spot UV comes out not too bad but it does not lay down really smooth. It almost looks like it is a little rough. Some samples I have seen of other spot uv looks really smooth.

Any thoughts on what I can do? Unfortunately I did not buy reducer so I guess I can give that a shot.

As well what it is the difference between a cylinder press versus regular screen methods besides speed I assume.

thanks

 

[TheProcessIStheproduct]

could be technique... are you curing good? try to scratch on it and a tape test, if curing good with you lamps, then maybe try to go with a 280 screen to put some more film down, it will kind of flow out and self level smooth...

 

[denisbunn]

Hi my name is Denis.
I specalise in uv lamps and there are mainly two types of lamps. That is they peak at different wave lenghts ie: 365nm or 425nm.
To ensure the correct lamp you need to know what the frequency of the materials best react to that you are using.
Your supplier normally can give you this information.
If you require any further information or advice please contact me by email: [email protected]