A subject that is coming to the forefront more than ever before.

I crosses several subjects and i starting to become something that I know is very workable in some situations.

I started in several places and with several parts but is just now coming together for several shops in a very profitable way.

Here is where it started.

Small shop of one person and limited occasional help, moves to a new location where wash development and reclaiming screens is an issue, reclaiming screens is almost impossible because of a new private sewage system.

The first answer this shop had was simple, just don't reclaim and tank the development water to be processed off sight by a public/commercial sewage collection service. This shop was collecting more than enough in charges to cover a new screen for each color - the answer was to buy screens, coat, and expose, then print and after use an on-press wash and set the screen off to the side to be discarded later. This presented a small storage issue, but a huge gain in production time available - zero time reclaiming screens. The screens are heavy and shipping was an issue. Of course I flinch at the thought of a screen "trash canned" like that and tried to convince the shop to at least sell them on e-bey, that failed, they did not want the designs to go to other shops (fair enough).

Final answer we worked out involves several steps and would not be a great fit for every shop but once all the cost and profit were reviewed with the gains in hours used for production rather than reclaim the results were dramatic. This is in action in several small shops currently.

Here is how the procedure works.

Base retensionable screens with table, three days of production.
Insert panels of mesh.
Degreasing chemical and/or chemical stain remover.
Capillary film preparation chemical.
Capillary film.
Quality positives for full exposure and lowest time and water use in wash development.
Current Manual printing equipment.
On-Press Wash of customer preference.

Shop did choose to use a hybrid frame and table with mesh panels, the needed mesh is chosen and locked onto the frame and brought to full tension.

Mesh is prepared for wet application of cap film by first an application of a mild stain remover and short pressure wash (less water use), mesh is then sprayed with a cap film preparation chemical and the necessary choice in cap film applied using the wed roll-on method (this saves a dry step).

Once the screen has the cap film applied it is dried in a high airflow drying cabinet and then exposed, washout is with a light mist and then high pressure wash out with a pressure washer in fan spray, this is where a quality positive lower water use.

Screen is dried then blocked out, dried, (often the block out is skipped) taped with a screen tape and used for printing.

Once the job is printed, rather than reclaim the screen the ink is dry-wiped then a mild on-press wash is used and the panel is removed with the screen table, the frame is placed in storage for the next use.

The snap in panels are a quick ship, light weight item that has a total cost lower than shipping heavy frames each job, possibly they could be sold or even reclaimed later if needed.

At first I thought the idea was heretical and insane until I reviewed the profits captured, efficiency wins, it's not for every shop but it does work, very well in the correct application.

So is it screen printing heresy? or in the right situation just good profitable business?

Chose an ink best for the substrate!

One of the longest running and frequent questions about printing on garments is the issue of fabric with polyester content and the use of plastisol ink.

The simple answer is that no matter how high quality your plastisol or how exotic the additives, there is a chance of "visual color transfer" often called bleeding.

The lower the content and effectiveness of your "blocking" additives and higher percentage of colored polyester content - the higher chance of that fabric color becoming visible in the ink layer. There is no plastisol that I have seen on the market - even the best available that cannot be defeated by even the simplest of red polyester garments.

There are now what seems like endless volumes of FREE information in this industry about the exact physical, temperature, and chemical interactions that cause "bleeding", in it's exact technical terminology but the simple answer is that polyester fabric and plastisol are and can interact because there is a basic chemical "compatibility" with the two products. This compatibility means that when we print plastisol on poly and heat it (as we need to cure it) this process can begin and can be so overwhelming that even the BEST of the "low-bleed" plastisol inks can be defeated. There are several stages involved in this color transfer I encourage you to read some of the excellent information from some of the respected quality Ink companies out there.

There are a few who will tell you that "bleeding" is all your fault, that you are just not keeping control of your heat with the flash or dryer - you only have to keep your heat high enough to cure plastisol and not go over the temp that causes the dyes in poly to start to sublimate (turn to a gas) often this is less than 10 deg. F. !

The other excuse I see is that the garments are of poor quality, and have too much dye, while this may all be true - often you (or your staff) have problems keeping tabs on your heat (like in the real world you never have problems ).

Of course to suggest that you can should only the highest quality fabrics to print or that you should control what garments the customer could order is ridiculous bordering on fallacious. Rather than attempt to cover for the weaknesses in a product why not find a quality alternative.

What to do?

Consider inks OTHER THAN plastisol.

Within a few months, there will be available (widely) on the market an ink that is a "dual-cure" that is formed by heat under 260 deg. F. into a "dry" layer and that within 24-48 hours makes a complete bond with the fabric - a silicone ink.

There are other products that are problematic, fabrics that are not capable of reaching the cure temp of plastisol without damage.

Recently an air dry, time cured ink became available on the market for products that cannot be heated to high temps.

While not as opaque as plastisol, simply lower the temp of your dryer, apply ventilation, this forms a dry layer over the product and the final drying can be in a ventilated area - great for the synthetic bags so popular in the grocrery stores now.

One of the most problematic garments are the athletic "wicking" products, swimsuits, spandex, and other garments that distort in and out of shape, plastisol with even the best "stretch" additive will never be able to stretch as much as the newer silicone inks.

Of course, to create an opaque layer of ink, especially with bright and dark garments the layer of ink is thicker, this can make things uncomfortable for the garment user, while somewhat unavoidable with plastisol as well as the newer inks, good control of deposit with quality screens can make this less uncomfortable, the choice may be a stiff water and air proof layer of stiff plastisol that has a high chance to bleed or a softer flexible coating that can be (but not always) rubber like. With the higher meshes the alternatives often have a softer hand than plastisol.

QCM inks makes the "rubber" but air dry ink, they can be contacted at the following:

QCM
930 Central Avenue South, Kent, Washington 98032 USA
1-800-321-0170
http://www.qcminks.com

Dow Corning is developing the silicone based ink, they can be contacted at the following:

http://www.dowcorning.com/content/textiles/screenprinting.asp

How to START to chose a line count (frequency) correctly for your mesh

There are simple answers and propeller head math junkie answers.

Unless I am mistaken you can find a rather complicated formula for finding exact (yet theoretical) size to mesh relationship.

I tell new people that they can start at 5.5 factors.

230 divided by 5.5 - 41.81 - I start with 42 most of the time.
305 divided by 5.5 - 55.45 - I start with 52

Reverse also - I have to have this broken into dots that are 36 LPI (frequency) so...

36 multiplied by 5.5 - giving 198 so to get the maximum theoretical ink volume (highest opacity by thickest deposit of ink) I can use a 196 to 200 mesh.

This is ONLY a SIMPLE starting point - for advanced users you have to consider emulsion choice (and it's ability to hold detail and bridge well), EOM and your particular mesh.

The best way is to start with a simple and easy idea and build on that with testing.

You can make positive strips with halftones of various LPI on each strip, shoot for your full and correct exposure and develop and print the various sizes with both dark ink on light backgrounds and white ink on dark background and save the results for your art development and choices for mesh and available detail.

You may have seen the debate about this, and because of a recent post about this subject I wanted to review a bit about the inexpensive drum tension tuner...

In fact, there have been several small screen printing supply companies who have used this exact type of tension meter. They often removed the original dial and replaced it with a new dial calibrated to NCM to use as a screen tension meter...

One of the draw-backs to the use of a drum tuner is that the drum tension tuners are deflection meters that are non-directional, unlike the screen tension meters where a base is machined with parallel ridges and a matching bar/ridge on the plunger to measure tension in a particular direction (Even with the ridges and bar there is some residual directional effect in the cross direction).

If you were willing to look for a tension meter (say from a friend) and calibrate a new dial for one of the inexpensive meters for yourself and live with the fact that the dial will only be circularly (omnidirectional - all directions) tension reactive...

If all you need or desire is basic tension in the center of the screen to prevent bursting the mesh then it could give you a reading more accurate than your finger or thumping and guessing, but not much more than a basic reading.

There are some who advise retensionable frames for beginners (and I would be one of them) many choose to propose that 110 mesh is hard to burst so you can live without a tension meter - possibly true. I on the other hand consider handicapping yourself with the typical 110 white mesh beginner albatross to be one of the reasons a new business can fail.

You will soon come up against the limitations with using retensionable screens and not using a deflection tension meter measured for NCM (newtons per centimeter) - quickly reaching bursting tension of the mesh and breaking the mesh (sadly the higher the mesh count the more expensive and more easily broken).

First, Stochastic is a bit of a play on words from the Greek into english - to aim, and to guess...

Basically to aim for a "general" result knowing that the end result will be slightly random and unpredictable.

1. Is a stochastic separation virtually the same as diffusion dither?

Almost, but even using first order stochastic dots with a good RIP there are better formations of dots.

Advanced RIP output often works by exchanging fixed grid square dots in a semi-random pattern for round dots semi-randomly placed in a similar fixed grid.

First order stochastic dots are considered primitive and problematic because of the secondary pattern.

The secondary pattern you see here in the red square...

Luckily for screen printers, using stochastic dots is FAR more forgiving of printing with mesh than with other transfer method printing procedures like offset printing.

2. What is the advantage of stochastic separations versus conventional elipitical dots?

On that, how about a bit on what is a conventional or stochastic halftone. Regardless of type "halftone dots" are an optical illusion, where the color is broken into small printable areas to create the illusion of "grey value" or lighter tints of the same color.

Conventional halftones are referred to as amplitude modulation or AM screening. This is an example...

Stochastic dots are known as frequency modulation or FM screening. This example is the more primitive "first order" stochastic screening, an example of the typical "diffusion dither" type.

The good and the bad...

Good--------------

a. Less chance of moire pattern

b. Less chance of frequency interference (moire type pattern on the screen caused by mesh pattern and the dots even before printing)

c. Less chance of moire type pattern forming from the weave of the garment and the dots printed

d. More forgiving in registration

e. More consistent in tone for longer into the print run

Bad--------------

a. Soft focus look (sometimes not a bad thing, like babies, women, flowers and nature prints)

b. Grain like visual effect to open and mid tone areas

c. Dot gain compensation is more difficult

d. Advanced Second Order, combination, and hybrid stochastic dots require expensive sophisticated RIP software

3. Some basic playing around appeared to have the stochastic seps spool/print much faster than the conventional. True?

If you mean that printing diffusion dither conversions from photoshop is faster - yes, the files are much smaller and take the RIP far less time to image because photoshop has already dictated the print placement. Stochastic screening generated from a RIP especially second order or hybrid takes longer to process because of the complex load on the RIP.

This is first and second order stochastic - first order is more primitive and second order is more random with random placement and random dots.

There are two forms of second order the first was random round dots outside of the typical grid and then, more advanced dots of random size AND random non-grid placement.

First order stochastic...

Second order advanced stochastic dots...

4. An article I found has me creating a layer for each chanel, converting to greyscale, then outputting as a bitmap at 150 with diffusion dither. Is this correct, or is there a better way?

You can adjust the dot formation DPI grid, but to form stochastic of the first order without a RIP programed to make stochastic you have to form them in photoshop as described above. You can also set photoshop to use patterns you pick, so you can play with the results, some will be horrid and some cool...

There is also a new hybrid screening technology where the dots change on the same positive from AM to FM screening and back, this is considered the most advanced technology. Hybrid technology uses each type of screening for its strongest features in the most advantageous positions.

Also many printers use a combination technique, where the yellow screen in four color process is stochastic and the other colors are AM screening - this allows the use of three of your best angles and discarding your worst performing angle of the four...

Other types of printing, like offset are working hard on this technology in a desperate attempt to gain an edge with image printing on flat goods like paper publishing. "Art publishing" where image of the print is the reason for the final consumer purchase, has been working with stochastic for many many years...

The first attempts at random pattern stochastic dots were with separations painstakingly sprayed by a skilled separation artist with an airbrush - long before computers!!!