Pad Printing Clean up and Pad care

[Twangpluckin]

Pad Printing Clean up and Pad care. I need simple solvent/cleaning solutions for silicone printing pads  and ink cups without getting locked into some overpriced product or confusing. Clean up is one issue, but cleaning and care of the silicone pad are of a greater concern.
Since I'm new to this, I guess it's best first apologize for using the SHOUTBox on this subject (sorry, my ignorance).
Anyway, I have a small start up business and will be doing Pad Printing. I have not used  my "used" SPC-84 machine as yet. See machine here:  http://besthotstamper.com/index.php/used-machines/1-color-automatic-pad-printer-01.html   It does seem to work mechanically, although the ceramic ring has not been tested for leaking or wear. But first, I have to solve the ink clean up issues. Most of the process/operation I understand, but don't want to rush in unprepared.
My photopolymer plates are being exposed with a Nuarc 26-1KS (used $300) at 7 minutes and  so far better than expected results.
However, I have experimented with a Press-a Print (manual) machine with poor results so far. This is more inexperience and procedure than anything else.  Pressure, ink viscosity, machine adjustment, etc.
So far I used ink thinner to clean and prep the plate (during and after printing) and lacquer thinner to clean up (not on the plate). Care was taken with the Print Pad and ink thinner was sparingly used to slightly "matte" the glossy finish of the new pad. Otherwise Windex was used for cleanup on the pad. One thing I found useful was that after most of the ink was removed ffom the open cup assembly and plate, LA's Totally Awesome Orange finished the job nicely with a warm water rinse.
Thanks in advance for any comments, ideas and/or suggestions.

[Frog]

First of all, welcome.
Don't sweat the shout box shout, I deleted it, but actually, many members do discuss problems there.
I just personally would rather they be more accessible to the whole group.

We do have a few pad printers here, and if your question gets things cooking, We'll probably make a pad printing section.

Otherwise, sorry, I got nuthin'

[Inkworks]

No short answers for you, sorry. Pad printing has no easy answers, be prepared for a loooooooong learning curve, after 20 years I'm still learning stuff.

We use lacquer thinner for general clean-up on everything for pad printing, but then we are using acid-etch steel plates so it's not a problem. Make sure you have good ventilation and get a good parts-washer tank with a pump that will handle lacquer thinner. These can be tough to source, but if you check with auto-paint suppliers in your area they should be able to point you in the right direction. The pumps tend to be pneumatic for lacquer thinner.

Pads are a different matter. The key to a good pad is the careful balance of the oils in the silicone, enough, but not too much. Brand new pads tends top be a bit too oily, and not print properly during the first runs, wiping with a soft cotton rag and some lacquer thinner will remove the excess oil that comes out as the pad flexes during break-in. The harder you compress the pad, the more oil squeezes out and you may have to wipe it down every couple of minutes. Keep in mind this isn't a huge amount of oil that you will actually see, but it's happening never the less. After a while the pad will stop squeezing out oil and become broken-in or stabilized and should print fine, at this point you shouldn't need to wipe it any more with lacquer thinner. Clean-up for the pad can be done using the sticky side of packing tape. We have a tape gun on each machine and often print on the sticky side of a piece of tape to drop dried ink off of the pad, or simply blot the pad with the same tape. After many thousands of impressions pads can lose their oil and start to become problematic with not releasing the print very well, they do have a finite lifetime. You can buy "pad oil" and by applying a thin film on the pad and compressing it on a smooth surface you can revitalize them to a point, you'll never get them to be like new as it's just not the same as when the pads are molded with the oils in the silicone in the first place, and after a while that $50-$200 pad is just garbage. Pretty much never buy used pads.. Store and handle them very carefully so they don't get scratched of damaged, even leaving something resting on a pad can eventuall leave a dent in them that will never come out, Also dust leaches oil out of them and can eventually render a pad useless.

The right pad for the job is KEY! if you just can't get a job running, try a different pad, generally, pointy pads for flatter objects, Blunter pads for round objects, but there are about a million exceptions to those rules. Hollow pads are a great tool for controlling image distortion too. Problems at the center of the pad in the image are the bane of padprinters, sometimes it's no problem, sometimes you just can't get that area perfect. The angle of the object being printed in the jig also plays a crucial role in how the image distorts. All of this doesn't even take into account durometer differences available in pads and it can quickly lead to having a $5000+ arsenal of pads to make sure you can handle whatever is thrown at you to print on.

Another indispensable piece of equipment for pad printing is a good hair dryer for each press. Get one with 2 speeds, and 3 heat settings (no heat, low and hot) and some way of manipulating the hair dryers position. Pad printing is all about managing the drying time of the ink-image being printed. First the ink in plate image has to dry a bit after the ink cup slides back, just enough for it to stick to the pad and be picked up, then once on the pad the bottom layer has to tack-dry enough for it to stick to the product being printed. Managing the drying of the image is done 3 ways:

1 - With the thinners and retarder in the ink. Several different speeds of thinners are available, you'll probably only need the medium speed thinner for 90% of your printing, but fast thinner is better for glass inks.

2 - The speed of the machine, and the speed of each part of the stroke (back, down, up and forward)

3 - The temperature and humidity in the shop, this is where the hair-dryer comes in, you can add heat and air-flow to speed up drying. 95% of the time when you need it, you'd use the hair dryer blowing on the pad as it moves forward before it prints onto the product. Be aware this will be blowing thinner out of the ink and will stink up your shop. Ideally you'll have ventilation on the other side to suck that out. Pad printing companies have a "pad-puffer" option which is essentially the same thing, sometimes just a stream of compressed air, they usually cost a small fortune and don't work any better than a $19.99 hair dryer.

Pad printing ink isn't really all that "wet" when it goes on the product, more of a tacky film of ink, but it has to be wet enough to stick to the object being printed on. Too much hair-dryer can be a real problem too, particularly with some inks (beware if the hardener ratio is 4:1) You can end up with the image transferring perfectly, but it just won't adhere to what you printed on, and the kicker is you often don't know for 24 hours until the ink has cured.....and can can produce a whole lot of product in 24 hours only to find that beautiful print scratches right off.

Another absolute key to being successful is image depth in the plate, you only have a few microns for a margin of error. Too shallow and the image will just never be opaque or glossy, too deep and you get voids and an image that will never transfer properly. Photpolymer plates make controlling the depth easier than acid etch, but a good plate is still the first step in success, and you can't fix a bad plate on-press no matter what you do.

[Twangpluckin]

Wanted to thank you guys for the replies.
There is nothing like getting verification of what you think you know and what you actually don't.
Since there are not a lot of forums for Pad Printing on the web,  it shows me there is a niche possible for me to earn a living. My biggest challenge now is to spend a few hours verifying that I can do this and then try to find some small run customers to get my feet wet. Hopefully test runs will happen this week.

Again, Thanks so much guys!

The wheels of progress often turn so slow, that you can hardly see them turning.

[Printficient]

Xenon F.S.I.C. should work.  Of course we buy back any chemistry that you do not like.  $36.50 per gallon