Varnishing on screen prints

glennn2000 · October 21st, 2012, 10:56 AM

Can I use a solvent based varnish mixed with linseed oil to brush over the top of a gloss vinyl ink silk screen print on paper? I have done it and, four days later, it is still tacky. I am starting by brushing the paper with a background colour using the EPI gloss vinyl ink thinned with the recommended thinner, once this is dry, I silk screen the image on top using the gloss vinyl ink, then once dry, I brush the varnish on top of the whole thing. The varnish, where it sits on the background colour dries no problem but where it sits on the silk screened foreground graphic is still tacky. I wouldnt bother to varnish but it adds a nice glossy consistency to the whole thing. Any ideas?... Thanks.

Binkspot · October 21st, 2012, 11:40 AM

IMO it could be two things. The ink is not compatible with the varnish and setting up a chem reaction not allowing the resins to cure. The other might be solvent penetration. This is where the ink may feel cures to the touch but still contains solvent that needs to evaporate to fully cure. Common problem qith multiable coats or layers of solvent based coatings.

Prosperi-Tees · October 21st, 2012, 11:56 AM

I believe the linseed oil added will greatly increase the dry time. Any oil based product even the varnish will take forever to dry. Have you tried an acrylic polyurethane? Don't know how that would work on paper though

glennn2000 · October 21st, 2012, 12:17 PM

Thanks a lot for your replies. The graphics are multiple colour prints so it could be that they werent cured sufficiently. Either way, I dont have forever to wait for these prints to dry; could I try a glossy clear screen printing ink instead...maybe thinned with something?

Thanks

Binkspot · October 21st, 2012, 05:40 PM

Heat, we run our vinly inks through a dryer. If not let stand for at least 24 hrs maybe more if it is cold or damp.

meshman · October 22nd, 2012, 03:01 PM

Order a clear gloss overprint that is compatible with your ink system from your ink supplier. Burn a screen with all the film positives taped together in register, then use that screen to overprint the gloss clear on top of your prints. That's how it's done to protect outdoor products from weathering and UV fading. Much easier than brushing also. Your linseed oil is reacting with the inks.