What types of products can I pad print?
- Pad printing is primarily used for non-uniform, multidimensional products like a golf ball. Flat surfaces can be pad printed as well.
- Typical image sizes are less than 3″ in diameter, but print sizes of 5″ or larger can be achieved in special occasions.
- You can pad print a very wide range of substrates, including plastics, metals, glass, ceramic, vinyl, rubber, polypropylene, leather, acrylic, cotton, even food items and more. A pad printer is NOT a documentation printer but it can be used for printing on paper products, for instance paper cubes or napkins.
How does pad printing work?
- Image is etched in a plate.
- The plate is flooded with ink and wiped clean, leaving ink in the etched area only.
- The surface of the ink becomes tacky causing in to cling to the printing pad and sealing that side of the ink film.
- Pad lifts the ink and exposes the other side of the ink film; ink becomes tacky and sticks to the part.
To learn more about this process, read the article: Pad Printing: The Inkcups Way
Can I print one color over another?
- Yes, pad printing inks are designed to print wet on wet: they dry very quickly.
How fast can I pad print?
- A typical semiautomatic 1-color pad printing machine gives 1000 IPH (impressions per hour) tempered by fixture and the speed of the operator who loads and unloads parts. A typical 2-color pad printer gives about 600 IPH. There are fully automated machines capable of speeds of 3,600 parts/hour.
What is the maximum number of colors a pad printer can print?
- Commonly, pad printers will print 1 to 4 colors. We have machines that offer up to 8 colors.
There is a light spot in my print. How do I fix this?
Most likely reasons:
- The light spot may be caused by plate scooping. If so, use a lower line screen (approximately 150 lines per inch).
- The spot can also be created by the point of the pad. In this case, select a pad with a lower point.
The ink is not picked from the plate. What should I do?
The ink is most likely drying in the etch. Make sure that:
- Plates are not too shallow.
- Ink is not too fast.
- Pad is not old/worn out.
- Ink cup has sufficient ink.
Why can’t I get full release of the image from the pad?
It is most likely one of the following two reasons: a) the ink is either too wet or too dry or b) the pad is old.
- To determine if it is an ink problem, touch the pad immediately after ink pick up. If the ink does not transfer to your hand, it is too dry. It means that your plate is too shallow or the thinner is too fast. If the ink does transfer, it may be too wet. Make sure your plate is not too deep and thinner is not too slow.
- To determine if the pad has dried out see if it just will not release ink no matter the ink formulation. The pad will not release ink if it has dried out. Depending on the degree of dryness, you need to replace the pad or restore it. Try our Nu-Pad Conditioner & Restorer formulated to replenish pad oils.
I’m getting small holes in my print. What’s causing this?
What typically causes “pinholes” is air being trapped in the etch by the pad. Possible reasons:
- Pad is too soft or too flat. Try a harder and pointier one.
- Plate is too deep. Try a shallower plate.
Why do my plates wear out fast/ scratch easily?
- Plates have not been fully post-cured. If you are able to dig your fingernail into the plate, you should post cure it for a longer period of time. Hint: leaving your plate in direct sunlight will post cure faster than most exposure systems.
- The pressure on the cup is too high.
- There is not enough ink in the ink cup causing the plate not to be lubricated. We recommend no less than 40 grams of ink in a 90mm cup.
What’s the most common plate problem?
- A plate being too shallow, which causes the ink to dry too fast. Please note: the shorter the exposure, the deeper you want the plate!
Why does my image look fuzzy with ‘spider webs’ in it?
- Plate is too deep.
- There is static electricity. Antistatic paste or Antistatic liquid for inks will resolve this problem. Request samples
- Ink is too thick.
- Pad is too flat.
My image is not opaque enough. How can I make it better?
- Check to make sure the pad is not over-compressing.
- Make sure plate is not too shallow.
- Make sure ink is not too thin.
- Use a harder pad which will pick up and lay down more ink.
- Try high density ink.
The image is distorted at the edges. What should I do?
- It’s a pad selection problem. If possible, use a larger pad (20% increase will most likely fix it). Alternatively, use a softer pad.
Why am I getting inconsistent image placement on my part?
- Part is not fixed properly and is “rocking.”
- Plate is not secured on the machine.
- Pad mount in not secured.
- Pad is too soft.
Previously cured prints became sticky after a few days. Why?
- Re-wetting is caused by plasticizers that migrate from the part to the ink. This is common for vinyl. You need to use ink designed specifically for vinyl.
Ink becomes thick too quickly. What is causing it?
- There is too much hardener.
- There is not enough thinner or wrong type of thinner.
- Ink is contaminated at mixing. Make sure your mixing container and mixing sticks as well as cleaners are acetone- and plasticizer-free. Contact Inkcups to consult!
How do I know whether ink viscosity is correct, whether it has enough thinner?
- In general, we recommend weighing ink and thinner when mixing. Typically the mixture is 15% thinner to the weight of the ink.
- To test mixed ink viscosity: dip a mixing stick, pull it out and allow the ink to drip from the stick, forming a figure 8 (the size that would fit in 8 ounce drinking cup). If the 8 disappears before you finish it, the ink is too thin. If ink puddles on top or if the 8 does not start disappearing by the time you finish it, the ink is too thick.
My print starts to disappear after 5-10 parts are run. I stop the machine for a period of time, then start again and the print comes back. Why?
- Thinner is too fast. Speed up the machine or mix new ink with slower thinner or retarder.
- The plate is too shallow and the ink is drying out.