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First try problems

Posted: Wed May 07, 2014 2:12 pm
by tickfawriver
Hello All,

I design and manufacture effect pedals Similar to guitar effect pedals) for harmonica players. Well long story short the supplier of my enclosures has discontinued their screen printing services so I have decided to do my own screening. I am screening on powder coated aluminum enclosures and gave it my first attempt today but had a problem. I am using acrylic water based ink to learn with but I play to switching to a solvent based ink as soon as I am confident.

Here is the result of our efforts today.

Image

As you can see there are spots where there is no ink, we started with the ink very thick and thinned the ink on subsequent tries but we had the same problem each time. We tried varying the amount of pressure and the angle of the squeegee (80 dur). One thing to note is that the screen seemed to stick to the substrate and not release, we tried different offsets but there was not improvement.

Any ideas?

Thanks
Randy
http://www.lonewolfblues.com

Re: First try problems

Posted: Thu May 08, 2014 10:44 am
by Catspit Productions
Well I am a textile screen printer so my experiences are limited with graphic printing. I would first begin testing with the appropriate ink for what you are printing. You don’t really want to set this up working with an ink that may not be behaving properly since it is not made to bond to powder coated materials. Half the battle here may be simply using the correct ink.

Also I would clean the print surface with denatured alcohol to remove finger grease and other oils that may repel ink. Water based acrylic ink may not perform the way you want it on this material. Therefore testing with that will not do much for you since as soon as you change inks the nature of things is likely to change.

Try contacting an ink maker and get the appropriate ink for your print surface. Then do the testing again and I think you will see much different results.

The screen may be sticky for various reasons. Perhaps the surface and emulsion are such that they “stick” to one another OR the acrylic ink is getting tacky during printing causing that feeling. Or there could be high humidity in the emulsion. Also you may want to see if there is a retarder for the ink you will need to use. The retarder additive will slow the ink down in drying times.

Re: First try problems

Posted: Thu May 08, 2014 6:55 pm
by tickfawriver
Thanks for the suggestions. I will try again with the appropriate ink and update with the results.

Randy

Re: First try problems

Posted: Fri May 09, 2014 1:44 pm
by Catspit Productions
You're very welcome. We look forward to hearing about your results and what actually works for you. Keep us posted ;)

Re: First try problems

Posted: Tue May 13, 2014 1:12 pm
by tickfawriver
I got the right ink, in this case it is Nazdar 9600 series and it went a lot better. There was no adhesion problems at all.

We printed about a dozen and did have some trouble with the smaller elements of the graphics, I think it may be that the ink was too thick to flow through some small circles and parts of letters like upper part of "A". We tried pressing harder but then the screen stuck to the enclosure and did not release. We stopped at this point to cleaned up and regroup.

Unfortunately I was too aggressive cleaning the screen and removed some small pieces of emulsion :oops:

I have another screen on order and we will try again, this time with the ink just a little thinner and not pressing too hard.

Randy

Re: First try problems

Posted: Wed May 14, 2014 5:32 pm
by Catspit Productions
Okay very cool. Progress.

Make sure the emulsion is resistant to the inks you are now using. I'm guessing it's a solvent ink. You may have to adjust artwork or bump up in mesh count to get the fine details you need. Also a thinner additive should be available for this ink if needed.

Thanks for the update. Let us know what happens next.