Choosing a Screen Printing Exposure Unit?

We are often asked “what is the best exposure unit for my screen printing business?”

Like always what seems a simple question does not have a simple answer. So we thought we would put this guide together to help work through your requirements and to come up with the right answer for you.

Let us first look at what YOU need for YOUR Screen Printing business. Think about these considerations and questions?

• How many screens do you plan to produce on a daily basis (a couple here and there or up to hundreds per day)
• What is the maximum screen size you use?
• Do you have any space limitations?
• Are you a hobbyist printer, commercial or educator?
• What is the size of your budget?
• What kind of artwork are you producing? E.g. Complex design with very detailed half tones / 4 Colour Process CMYK or typical T Shirt artwork (medium resolution / block style artwork)
• We are going to do our best to avoid baffling techy jargon

Now let us look at the Exposure Unit solutions from simple to heavy duty.

WPS LED Exposure Lamp

WPS LED Exposure Lamp is a simple solution,  which are used every day. Good for hobbyists / home printers who make a handful of screens per day. Comes as part of our Screen Printing Kit range.

Pro: Very Cost Effective, can create excellent stencils and you can expose large screens. Note that the lamp does not have a vacuum therefore you need to ensure that the positive is tight and intimate with the screen. To do this you use sheet of glass (the heavier the better) which ensures that the film positive and screen are very tight.

This Exposure Unit uses LED which are powerful and reliable. They are very energy efficient and do not generate heat.

Cons: Can be slow (5 – 20 minutes depending on screen size) depending on the screen printing emulsions, requires space (large cupboards are ideal), the printer has to time the stencil exposure – there is nothing ‘hi tech’ about the lamp solution but it works.

WPS Mini Exposure Unit

 

The WPS Mini Exposure Unit uses proven “Actinic” tubes in a tight array. This exposure unit comes with a yellow pilot light which you use to position the film positive with the screen. The unit comes with an integrated timer (you can set multiple programs) and vacuum which is extremely easy to use.

We have used these units for a number of years and have been pleasantly surprised at the quality of stencil produced even with very difficult artwork. Typical exposure times from 120 – 300 seconds depending on what kind of emulsion and the number of coats you are using.

Drying Cabinet Ideal for small print shops, schools and colleges –  You can also purchase the unit with a drying cabinet which really does improve production with a relatively small footprint.

Pros: Very easy to use, very tight vacuum, and uses proven technology giving high quality stencils. Different sizes of exposure unit available to accommodate different frame sizes.

Cons: Not many, if you are a creating lots of screens you will have to replace tubes at some point.  Traditionally there has been debate that  tube units do not produce stencils as sharp as from a single light source. With tube units, light comes from multiple angles, potentially undercutting the positive during exposure which can result in the loss of fine detail. However our units have a dense tube array  we have not experienced many issues at all with this kind of unit.

These units can be used in a high production environment e.g. 50 – 70 screens per days. However do budget to replace the bulbs on a regular basis as they will gradually degrade.  You can always choose the LED version.

WPS LED Mini Exposure Unit

The WPS LED Mini Exposure Unit, consist of UV LED technology positioned in a tight array, similar format to the “Actinic” version. It comes with a yellow pilot light which you use to position the film positive with the screen. The unit comes with an integrated timer (you can set multiple programs) and vacuum which is extremely easy to use.

LED technology has started to make inroads into the screen printing industry, so the technology is relatively new and is continuing to be developed. Like the standard unit it also available with a built in drying cabinet which is great for increasing production and reducing mess.

Pros: Very quick (15 – 300 seconds depending on emulsion / number of coats etc.). Very easy to use, very tight vacuum, LED technology using low power, does not generate heat. LEDs are long lasting (stated to be very long life) and produce high quality stencils. Different sizes of exposure unit available to accommodate different frame sizes.

Cons: Initial purchase price higher than Actinic units. The LED array emits light from multiple angles undercutting the positive during exposure which can result in the loss of fine detail. However with LED technology this seems less of a problem than tube units and is commonly not considered a problem for the vast numbers of printers (99.9%).

LED technology is new and is continuing be developed.  The LED are to be manufactured to emit the correct light frequency, you can’t use generic LEDs for exposing screens.

Ideal for small / mid, large screen printing shops and educational establishments who need to produce lots of screens quickly. These units are designed for high production environments. There are also version available for printers who have invested in direct to screen technology.

 

WPS Heavy Duty Exposure Unit

The Heavy Duty Unit uses a  Metal Halide bulb, they come in lots of different configurations.  Including different bulb ratings and features such as integrators.  An Integrator measures the quantity of light reaching the screen and adjusts the exposure if there are any voltage fluctuations or to compensate for deteriorating bulbs.  Some units have rapid start-up, it can take time for a metal halide bulb to get to the correct operating temperature. These units are fast and give very accurate stencils.

Metal Halide is still probably the most popular light source used for mid and large screen printers.  Some Heavy Duty Units use a Halogen bulb.  This type of bulb are rapidly going out of production.

Pros: Very fast (depending on the power options you choose). They come with advanced features so you can produce large numbers of stencils quickly, consistently and accurately. Often used in heavy industry environments and for used for multi applications e.g. exposing print plates. Different sizes of exposure unit available to accommodate different frame sizes.

Cons: Metal Halide bulbs are expensive (£200 – £400 common prices).  They generate heat and consume much more energy than LED units (LED exposure units typically use 1/5 of the energy of a metal halide unit). Many screen printers are moving over to LED technology.

 

In summary

When choosing an exposure unit take some time and think about your current and future screen printing requirements. There are lots of exposure units to choose from all giving different levels of production capability and quality.

The exposure units with combined drying cabinets are very cost effective and increase productivity. If you are looking to replace an older unit e.g. metal halide unit.  We would highly recommend that you consider LED units.

Please feel free to contact us to discuss your requirements. We can help you to find the right exposure solution for your needs. sales@inkandsolvents.co.uk

 

Choosing a Screen Printing Emulsion

Choosing the right screen printing emulsion (also known as photosensitive emulsion) is a little like buying a car, they all effectively do the same thing but have different features, methods of use and performance factors which differentiates them.

All of the emulsions react to UV light causing the emulsion to cure and harden. If you are new to screen printing check out our tutorial on YouTube which covers the basics and shows you how to create a stencil using photosensitive emulsion.

There are three main groups of emulsions on the market:-

• Diazo – been in use for many years, the emulsion needs to be sensitised before use. They come with the sensitiser is a separate pot or sachet.
• Photopolymer, sometimes referred to as SBQ Photopolymer (Styryl Basolium Quaternary). The manufacturers mix in the sensitiser with a polyvinyl base meaning that the emulsion is ready to use and you don’t have to mix in a sensitiser. Commonly known as ‘One Pot’ emulsions.
• Dual Cure – a combination of both types of emulsion but mostly (there are some exceptions) need to be sensitised before use. Dual Cure emulsions are the most popular as they incorporate the strengths and weaknesses of Diazo and Photopolymer emulsions.

Autosol 6000  Diazo Emulsion (Authors favourite when using waterbased inks)

 

Diazo Emulsion – Pro

Con

They have a wide exposure latitude (so very forgiving if you have not got your exposure timings spot on)    Cost effective and reliable   Can be formulated to be water resistant or solvent resistant e.g. if you use waterbased inks you need a water resistant emulsion and if you use plastisol and solvent inks you need a solvent resistant emulsion   We sell Autosol 6000 and Sericol Dirasol 25

Less light sensitive than the other emulsions so if you light source (exposure unit / lamp etc) is not stronger you could be exposing for a while!    Not so good for fine detail and halftones (often subject to much debate) , Diazo emulsions are normally quite thick but this is not always the case with all of the Diazo emulsions on the market.   More difficult to reclaim than the other emulsions especially the water resistant variants.

Chromaline CTR Photopolymer Direct Emulsion

 

Photopolymer Emulsions – Pro

Con

One Pot – you don’t have to mix in with Sensitiser powder which is unpleasant stuff and is fraught with health and safety issues.    Good for high production print shops   Easy for reclaiming the screen   Can be formulated to be water resistant or solvent resistant e.g. if you use waterbased inks you need a water resistant emulsion and if you use plastisol and solvent inks you need a solvent resistant emulsion   We sell Chromaline, Ulano, Sericol and Macdermid ranges of Photopolymer emulsons

Very light sensitive – you also need a strong reliable light source e.g. Metal Halide / LED and in some circumstances Actinic / Tube units.    Your exposure timings have to be spot on.   Typically the most expensive emulsion

Autosol 5000 – Very Popular Universal Dual Cure Emulsion

 

Diazo Emulsion – Dual Cure

Con

They are relatively quick to expose and work with most light sources   They have a wide exposure latitude (so very forgiving if you have not got your exposure timings spot on)   Cost effective and reliable   Good for fine detail and half tones   Easier to reclaim the screen compared to Diazo emulsions   Can be formulated to be water resistant or solvent resistant e.g. if you use waterbased inks you need a water resistant emulsion and if you use plastisol and solvent inks you need a solvent resistant emulsion   We sell Ulano Proclaim, Macdermid Autosol and a wide range of Sericol and Chromaline emulsions

Shelf life is not so good as Photopolymers     Most Dual Cure emulsion need to be sensitised, but one pot solutions are now on the market such as Ulano EC

Ulano EC one of the first ‘one pot’ Dual Cure emulsions on the market, also has 18 months shelf life. No need to add sensitiser – ready to use straight from the pot.

 

 

 

 

Tips

• Choose the emulsion which gives the right stencil resistance e.g. if you are using Plastisol then choose an emulsions which gives a solvent resistant stencil and water resistant if using waterbased inks. Otherwise you will find your stencil starting to break down.
• Some dual cure emulsions can be used with both water based and Plastisol inks. However if you are using the same emulsion we recommend that you ‘double bake’ . This increases the exposer the screen again after it has initially dried to strengthen the stencil.
• If you are using wate rbased discharge inks for large scale production.  We recommend emulsion which is  designed for discharge inks such as MagnaPrint.
• Keep the emulsions in the fridge (but don’t freeze) it will extend the usable life
• If you use sensitiser powder emulsions always follow the instructions. Mix the powder in well and leave for a couple of hours to let the air out the emulsion before use
• If you don’t have a strong light source, don’t want the hassle of sensitiser powder. Ideal if you don’t expose many screens then try out a one pot dual cure such as Ulano EC it is rather good

I want the print to have a soft touch?

What is a discharge ink?

Here at Wicked Printing Stuff we don’t expect you to know everything and we are happy to explain things.

So you want to print a light colour on a dark garment and you want it to feel soft. Now plastisol inks wrap colour AROUND the threads but gives a rubbery feel (also referred to as hand) but is bright. So ideally you want a water based ink. For those of you that have tried this and I can hear you shouting at the back, but I have tried water based inks and I just can’t get a good opaque print, that’s why I use plastisol. Well that’s where the discharge inks come in!

For the punk rockers out there, remember how you got that bright green hair, that is right you had to bleach out your own hair colour first so the back ground colour was white, only then the colour would take and be vibrant and striking. It is almost the same in screen printing but we use discharge inks that need curing. The discharge ink actually removes the dye.

 

First off you have to have the right garment fabric, it has to be 100% cotton and it has to be dyed with a dischargeable dye. So check with the manufacturer. If the garment is a mixture of cotton and polyester only the cotton will discharge. Now that might actually suit you but you would need to do a trial run to make sure you get the effect you want.

 

So having got the right garment now we need the right ink. There are a lot out there and some are more complicated to use than others.

Water based dischargeable inks are the easiest and most eco friendly ones to use. The process works during curing when the discharge removes the original dye and the ink gives the new colour. To do this you add activator to the ink which ensures you get an intense colour.

 

At Wicked Printing Stuff we have researched the products extensively.  As a consequence we have developed our own range  the splendid WPS Premium Discharge Ink.   The ink is based on MagnaPrint AW .  Which has been developed to meet the most recent ecological requirements.

 

For the discharge process to work, you do need a tunnel dryer (the longer the better).  Typically 90-120 seconds dwell time is needed for a good cure. You can also use a heat press which is great for low production. You also need well ventilated premises and printers should read the MSDS and be aware of any health and safety consideration.

A decent film positive is an essential part of achieving a great stencil as part of the exposure process.  A simple test is to hold your film positives up to the light.  If the light can be seen through the artwork then the positive is not dark enough.  We do not want the light getting through the artwork when exposing.

Good time to take a look at our exposure issues guide.

So some tips…

Double up on your film – print out 2 copies then cut the corners off one of the films, line them up and stick together with invisible tape. Make sure that the film positive is nice and tight against the screen.  Especially if using a lamp system and does not have a vacuum.  Some purists will be frowning at this solution, but it works!

Use decent film positive paper, inkjet film is coated to ensure that ink completely adheres to the paper which in turn makes the artwork darker.

Get yourself an Epson – they seem to be the best at putting down more black than many other brands. The Epson printers are rather good recommended models – 1500W (if you can find one) and the Epson ET14000 – use the blacquer ink system which is designed purely for making film positives – it’s very cost effective and does the job. The ET14000 using bulk ink tanks rather than cartridges – Key Tip is to use the printer on a regular basis ideally every workday to reduce ink drying issues.

 

 

If you are using a laser printer then buy an Epson (sorry showing a bit of a personal preference there).  There are some Canon printers are apparently good for Film Positives. Seriously if you are using a laser then you can use a toner density spray which makes the artwork darker. The old technique was to paint oil (vegetable most popular or white spirit) over the artwork – but rather unpleasant!

 

Having issues exposing screens?  Then take a look at our Exposure Troubleshooting Guide.

Having problems getting the right exposure times?

Stencil not washing out?

Stencil too easily losing definition?

Experiencing stencil breakdown whilst printing?

There can be lots of reasons for these problems so we have compiled a simple troubleshooting guide which might help you. It won’t solve every problem but hopefully will point you in the right direction.

Problem	Possible reason and remedy
Image will not washout	Are you using the right level of water pressure? You can use a power hose using light to medium pressure. Normal tap pressure is not enough. If using a pressure washer, is set it to its lowest setting? How opaque is the film positive? Hold it up to the light. If it is letting light pass through then the emulsion will start to harden making washout difficult. Make sure your film positive printer is set to the darkest settings, you can print out 2 copies of the film positive and stick them together.   You can also use a density spray if printing Film Positives on a laser printer. Has the emulsion gone past its shelf life? Write the date on the label when sensitising – it may save a lot of time and frustration. Screen maybe over exposed. Check your exposure timings – you can use an exposure calculator to determine the right timings / settings for your exposure unit Make sure when drying the screen after coating that you don’t overheat it. Temperature needs to be kept below 40c.
Not all of the image washes out or washes out easily	Screen likely to be under exposed other tell-tale signs include: If the water runoff is heavily emulsion coloured when washing out and if the emulsion feels slippery and soft. ·         Check your exposure timings – you can use an exposure calculator to determine the right timings / settings for your exposure unit Check for uneven contact between the positive film and screen when exposing. Check the vacuum is working correctly / or glass & weights are in place. Could be uneven coating of emulsion on the screen. Check the tension of the screen – if it is loose you will not get an even coating of emulsion. Maybe time to get the screen re-stretched. Only use light to medium water pressure – too much pressure can remove the artwork inadvertently, resist the temptation to give the artwork a blast with the power washer on anything but light setting. After initially wetting the screen on both sides, washout from the print side only with just a final rinse on the squeegee side. Make sure that the emulsion has been sensitised correctly, the sensitizer powder must be completely dissolved – maybe consider a pre-sensitized emulsion such as Ulano Proclaim EC. Always degrease the screen before coating with emulsion it helps the emulsion adhere to the mesh as well reducing the chance of pinholes and fish eyes
Stencil washed out but ink won’t go through part of it when printing	Check your exposure timings as the screen is likely to be underexposed – you can use an exposure calculator to determine the right timings / settings for your exposure unit Make sure that the emulsion is thoroughly washed out as the emulsion can run into the stencil on the squeegee side blocking the artwork. Sometimes you can clean it out with a damp cloth (luck is involved – so best to get the exposure timing and washout right) Stencil not dried properly after washing out – you can’t beat a drying cabinet (either manufacturer or homemade). Always inspect the stencil in the light to make sure no moisture remains. Before exposing make sure that the screen is completely dry, the emulsion should be the same ambient temperature of the drying room. If the emulsion is cooler it still has some water content.
Fish Eyes	Normally caused by contamination so make sure you have degreased your screen thoroughly and that your workspace is clean. Also check that the exposure unit glass is clean and that there is no contamination on the film positive. Check that the coating trough is clean, dust free and that the edge is completely clean (make sure there is no evidence of the old emulsion on the coating trough). When coating the screen, move the trough steadily and with purpose. If you coat too fast the emulsion won’t adhere to the screen correctly. Conversely if you coat too slow and the coating may be too thick. Fish Eyes can also occur during printing if there is an issue with the emulsion e.g. over its shelf life
Pinholes	Similar to Fish Eyes – watch out for contamination on the mesh so make sure you degrease screens. Dirty glass on the exposure unit is often a culprit, or contaminated film positives. Make sure that there are no air bubbles in the emulsion when coating – when sensitizing emulsion leave it at least for a couple of hours (ideally leave overnight) before using it to allow the air to escape. Don’t coat too fast – allow the emulsion to adhere and fill the mesh aperture

 

Top Tip – Useful tools

Chromaline Exposure Calculator

Chromaline exposure calculator eliminates miscalculated exposure time with three kinds of quality checks. An easy, user friendly tool for the novice and the advanced screen maker.

Designed to help determine correct exposure time, print quality check and halftone tests.

https://www.wickedprintingstuff.com/exposing_equipment_and_digital_screen_makers/accessories_inc_bulbs_foam_and_exposure_calculator_LC241/chromaline_exposure_calculator_P2548.html

 

Maybe the best investment you make!

Simple Guide to screen printing Plastisol Transfers

Plastisol Transfer are a great way to make your screen printing business more flexible and reactive to customer need especially when you receive repeat orders of the same design. Instead of printing direct to the garment, you print onto a transfer paper which can be heat pressed onto the garment at a later date.

How do you make a single colour transfer?

Prepare your screen, coat the print side (side closest to the garment) 3 times and squeegee side at least once with emulsion (using a dual cure emulsion).  If you are using one of our WPS Essential coating troughs then you can use the thick edge which will give you thick covering of emulsion in one coat.  Remember to fill the trough at least ¾ full – you don’t want to run out of emulsion.

The artwork needs to be mirror image.  Expose the screen (note – you will need to increase exposure time when adding additional coats of emulsion).  Check our exposure troubleshooting guide.

Tape up the screen and register on your press as per normal.

In this article I am printing onto a dark garment  using WPS Premium Cotton White Plastisol Ink.  We recommend that you use the high opacity inks rather than mixing inks.  When printing transfers you need a thicker deposit of ink compared to a direct print.  We are using a squeegee with a 65 durometer blade (soft square cut blade) as we need a good deposit of ink to go through the mesh (using a 43T with white mesh).

Spray some hi-tak down on the platen, alternatively you can use a vacuum board as the paper needs to be kept firm on the platen.

Place the transfer paper on the platen and make sure it is firmly positioned.  In this article we are using cold peel transfer paper which gives us a heavier deposit of ink.  You can use hot peel paper (we will discuss the differences in a later article).  You can print on either side of the paper.

Flood the stencil with ink and print as per normal. One of the reasons of having extra coats of emulsion is to give a thicker stencil.  We don’t want to utilise print / flash / print steps when printing transfers.  We want (and need) as much ink to go through in one print stroke.

Lift the screen, you will see the printed paper.

You now need to cover the print with transfer adhesive powder, this ensures that the ink adheres to the garment.  Cover all of the ink with a fine coating of powder.  In this article I have simply poured the powder from the tub – you can use sugar / salt shakers. There are many techniques for manual powder application.   I am often asked about not using a transfer adhesive powder – it is possible to get a good result without the powder but it is rather hit and miss.

Make sure all of the ink is covered with powder, then put the excess powder back in the pot.  The next step is to touch dry the ink – in this article I have used a heat press setting the heat platen at least 2-3 mm from the ink. The temperature  on the heat press set to 180 degrees C and timed for 10 secs – just enough to tough dry the ink).  If you are producing lots of transfers it is best to use a tunnel dryer. You set the belt speed high, you do not want to cure the ink.

When you have your printed transfer you can file them away (keep dry and avoid humidity) and heat press onto the garment a year or so later.

When you are ready to apply the transfer, place the paper on the garment (print facing down).  I am using a clam heat press but swing away heat presses work just as well.  Set a tight pressure and heat press (180 degrees C for 20 – 30 seconds depending on how good your heat press is. You might have to experiment to get the right results).

After heat pressing the transfer, rub the back of the transfer with an old T Shirt.  Note – this is more habit on my part but it always seems to work!  After 40 seconds peel off the paper.

After peeling back the paper you are left with the end product, a very opaque and soft hand print.

 

 

How to Create High build stencils

Illustrated Step by Step Guide

Looking to give your designs the edge with a 3D raised look or wanting to add some texture to your designs?  High build stencils are also used extensively when printing circuit boards, applying varnishes to give a raised feel and for applications such as non-slip socks.  Then you will need know how to create a high build stencil.

You have a couple of options, you can use direct emulsion and build up the coats or you can use a capillary film – which is a sheet already coated with an emulsion.  In this article we are using Chromaline Phat Film which is the quickest and easiest way to create the high build stencil.

Phat Film comes in various sizes giving a stencil depth from 100 – 700 microns,  in this article we are using 200 micron film,  to give you some comparison a 43T mesh screen with a coat on both squeegee and print side will give you stencil depth of around 25 microns.

So to get the same stencil depth as a 200 micron film, that works out that you would need at least 9 – 10 coats of emulsion which needs to be applied when the screen has dried, which equals lots of work and lots of time (over a day to prepare one screen!).  Also to get consistent coats is difficult and there is always a risk that another emulsion coat which be added to a coat which has not completely dried which reduces light sensitively and can lead to premature stencil failure.

How did we do it?

Step 1

We printed out our film positive as per normal, we are using  an Epson 1500W with Blacquer Ink – it is really important that the artwork is as dark as possible.  Hold your positive up to the light and if you can see the light through the artwork then print 2 copies out and stick them together with invisible tape.  TIP – you can print one of the copies out in Red, which is a colour which blocks UV light.   PHAT film is coated in a Photopolymer emulsion which is fast exposing but you need to be as accurate with exposure timings as much as possible.

Step 2

Degrease your screen as per normal using a degreaser and power hose.  In this article we are using a 32T screen.  It is best to use low mesh count screens when using high build stencils. Make sure your screen is completely free of grease and dirt.

Dry the screen.

Step 3

We use a standard dual cure emulsion to laminate the PHAT film onto the mesh.  We performed the steps in sub dued light.
Remove the cover sheet of the PHAT film.

Place the screen print side down onto the PHAT film, we are lucky enough to have a clean platen to rest on otherwise use a table (make sure the surface is clean and free of any dust).

Put some blocking tape squeegee side of the screen around the edges of the film.

 

Needed to laminate the PHAT film to the mesh using a dual cure emulsion, you can pretty much use any dual cure emulsion – in this article we are using Macdermid Autosol 5000 which was already sensitised and ready to go.   We poured a ridge of emulsion onto the taped area of the mesh.

Using a squeegee (Medium 75 green are perfect for this) to cover the PHAT film. Use the same pressure as if you were flooding the screen.  You will likely have to coat 4 times using the squeegee – if you can hear the squeegee rub on the mesh it means you need more coats of emulsion.

Put any excess emulsion back in the pot.

Put the screen in your drying cabinet.  Make sure the emulsion is completely dry before moving to the next step.

Peel off the thicker release sheet (if the release sheet puts up some resistance then leave the screen to dry for a little longer) then try again.  After you have removed the sheet then put the screen back in the drying cabinet for 5 mins or so.

Step 4

Exposing the artwork
Align the film positive to the PHAT film

We then exposed the screen for 350 seconds, we are using a WPS Mini Exposure Unit (uses actinic tubes) with built in drying cabinet.  We are using a 200 micron film so you will need to adjust the timings of your exposure unit based on the bulb strength, type of bulb and thickness of the film.

Step 5

Washing out the Stencil
After the screen has completed the exposure time then we are ready to wash out the stencil.  The best way to do this is to prepare some hot water (hot bath temperature).  Use a sponge, dip it in the hot water and gently rub the stencil.  If you don’t use hot water you could spend 10 minutes or more trying to washout the stencil using the power hose by itself.

When the stencil is clear, use the power hose (or power washer on low pressure) to wash off any residue. Remove the blocking tape. Give the squeegee side a spray and start to remove the blocking tape, don’t be surprised to see some evidence of emulsion run off suggesting under exposure.  Don’t worry this is normal but make sure you give it a good enough wash squeegee side to make sure there is no emulsion residue in the Stencil.

The screen is now ready to go in the drying cabinet.  Don’t worry if you see any blisters around the edges of the film – this is because the light has not gone through the blocking tape.  If there is blistering across the film then the film is underexposed.

When the screen is completely dry we are now ready to apply blocking tape to uncovered areas of the screen.  As an option when you are laminate the PHAT film with emulsion you could cover up the rest of the screen – in this article we have used blocking tape.

Step 6

Printing
We are using WPS Premium Cotton White Ink and a 65 Blade (Red) Squeegee – softer the blade the better as we need to get plenty of ink to flood into the stencil.  We double flooded the stencil prior to printing.

To increase the opacity and depth of the print, we printed out the stencil – flash dried the ink and double flooded the stencil again and printed again. (AKA Print – Flash – Print)

Important – with a high build print, there is a lot of ink on the garment.  You will need to increase the curing time to ensure of the ink is completely cured.

What do you need to create a High Density Stencil?

We used the following equipment and consumables:-

WPS Degreaser

Epson 1500W using Blacquer High Density Black Ink

A4 Inkjet Positive Paper

Chromaline PHAT film 200 micron

Autosol 5000 Dual Cure Emulsion (laminate the film onto the mesh)]

Blocking tape

Aluminium Screen 23 x 31 32T Mesh

Squeegee Wood – Blade 75 Green

Squeegee Wood – Blade 65 Red

WPS Mini Exposure Unit with Integrated Drying Cabinet

WPS Premium Cotton White Plastisol Ink

KFIX hitak spray

WPS 6 colour 6 station carousel
We used a Hot Air Gun to touch try the ink instead of a flash dryer and we used a Heat Press for curing – if printing a production run we would use a tunnel dryer.