Spot gloss effect similiar to UV with conventional press

[jeffrbauer]

I am trying to print a spot gloss image on a black uncoated cover that looks similar to a UV gloss process. I will be running it on a conventional Heidelberg Speedmaster CD74.
I don't have much experience with coatings and varnishes. I have used the AQ unit to flood coat items and I have gloss and dull coating supplies though I have never used the gloss. I have used an overprint varnish on a white uncoated stock and realized it doesn't show. (I don't know if it would be different on a black uncoated stock)

I have thought about a few different approaches and I'm not sure how the press sheet would turn out. Time is not a factor so multiple passes as well as polishing with impression rollers are possibilities.

1. Just run a high gloss varnish.
2. Run a high gloss varnish and flood coat with dull AQ.
3. Run a dull gloss varnish and flood coat with dull AQ.
4. Run a gloss gloss varnish and flood coat with gloss AQ.
5. Run a dull gloss varnish and flood coat with dull AQ.

Or do the same as above in with AQ first and another pass with varnish?
Do I need to look for specifically for overprint?

Thanks for any help.

 

[67drake]

How high of a gloss level are you looking for? Is the spot image supposed to be actually glossy when you are done,or are you just looking for contrast between the varnished and unvarnished areas?
If you have aqueous coated uncoated stock before,you know it has a tendency to want to curl,even on cover stocks,this makes multiple passes challenging sometimes,even more so when register is critical.BUT the coating can help seal the sheet,so a second pass with a gloss varn on top of it might hold out more than if it was not Aqueous coated on the first pass.
Just an idea,I don't know what the piece looks like,of coarse,but if you are trying to get the spot varn to stand out from the surrounding areas,adding 1-2% opaque white or silver to the varnish may help. You should not see the color so much at this level,but sometimes it can fool your eye into thinking that there is more contrast between the varnished and unvarnished areas,gloss wise. This effect works great sometimes on dark colored stocks,depending on the effect you are looking for.Like I said,Just an idea.
If you have an ink lab,or access to a "little joe" ,you may want to play around with a few ideas (multiple hits,varn over coating,ect.) before it goes on press.
Another idea would be to size the areas that are to be spot varnished,this could be done inline if run on a multi color press,that should help with the holdout also.

 

[Bret Hesler]

Several years ago, i was involved with a project looking for a similar effect. Here is what we did:
First pass - sized sheet with varnish
Second pass - double hit of PMS color plus AQ primer
Third pass - re- hit the sheet with AQ primer
Fourth Pass - sent out for UV at a screen printer

It was a lot of passes, but it did give a high gloss result.

Bret

 

[Bob Peterson]

With all of the passes involved you would be better off sending it out to have a clear stamp (foil) applied. This would give the gloss your lookin for at a lower overall cost.

 

[jeffrbauer]

Sorry but outsourcing the job is not an option because it is completely student produced for a technical conference competition.

I guess I am mainly looking for a contrast from the uncoated black. I realize that I can't get a thick film like UV or foil. I'm just not sure how it will show on uncoated paper.

A Heidelberg trainer told me about playing around with the AQ and varnish to get a contrast effect. I would also need to figure out what varnish to order.

 

[Bret Hesler]

Well then, your best bet is probably multi pass dry trapping. We had business cards printed and the designer wanted a varnish effect on the back. The first pass varnish soaked right in, but the second pass made the effect. You might need a third pass to get the effect you are looking for.

Bret

 

[Sfdp2300]

If your looking for maximum reflectivness out of your varnish on the dark uncoated sheet sounds like you may want to Dull AQ the sheet first and applie spot varnish on second pass. The Idea 67Drake has sounds good too with adding the 1%-2% silver. I might try this just to see what happens..

We ran an endsheet a couple of months ago were the customer asked for a PMS close to the same color as the sheet we were running, Of corse the ink pretty much disappeared but you still had a mild gloss effect on the sheet and that was with out any gloss enhancments. It would have looked very nice in design if they would have used sheet color other than a cream white.

 

[snydawg]

Have you tried the Strike Through ? I have seen the results of this process but have not been able to duplicate it yet. We have had fairly good results but not there yet. This can be done in 1 pass using a dull varnish plate with image knocked out that you want to be glossy and flood coat with gloss. We have a 5/c with coating CD 74 with a 10 BCM Analox Roller