High-resolution screen printing demystified--make money online

A complete guide to making high-resolution screen prints with minimal tools.

Notes: When applying film emulsion to the screen, the matte surface should face the screen.  The glossy surface is the plastic backing, which is removed later, just before exposure.

The resolution test shown in the video actually indicates line width, not pitch.  So, the 1mm sample has 1mm lines and 1mm spaces.  Thus, the pitch is actually 2mm.

The Nazdar paint instructions say there is a 30 minute "induction" period that is needed for the catalyst to start working.  Nope. Just weigh out the paint and catalyst, mix, and immediately apply to the screen. Print the needed items quickly, and clean it off the screen as soon as possible.  Use disposable mixing cups / tools.  It is *messy*!

If your emulsion is not sticking to the screen, even with very long exposure times, it probably isn't dry.  The green film may seem fairly dry after a few hours, but adhesion during the wash out process will be poor until it is really completely dry, then exposed.

today on Applied Science we're going to

talk about screen printing this is a

well known process for transferring

graphics on to a variety of different

substrates and so you'd think there

would be a lot of great info on the web

about getting started perhaps even a kit

of all the equipment you need to do this

but surprisingly there is almost no

information available for printing stuff

other than t-shirts and so in this video

I'm going to describe all the equipment

that I used after trying a bunch of

different things and you'll be able to

save a lot of time if you want to get

into this okay so the basic process goes

like this we take an empty screen and

coat it with a chemical that is

photosensitive and let it dry and then

we take a transparent or translucent

printout from an ordinary desktop

printer and put it in good contact with

the layer with the photosensitive layer

and shine light on it and wherever light

goes through the transparency and hits

the photosensitive layer it will become

insoluble in water and all the areas

that were kept dark will be soluble in

water so after the exposure is over we

take this to an ordinary sink just plain

water will rinse away the photosensitive

layer where we don't want it so then

we're left with a screen that is

patterned and there's open areas

wherever we had a dark area in the

printout then we suspend this above the

object we want to print and squeeze ink

through all those open areas pretty

straightforward but going to the moon is

also pretty straightforward if you just

say we blast off and then we land it's

really the details that determine

whether a process is tricky or not and

so let's step through the process kind

of sequentially and I'll point out all

the different choices you have and all

the best things you should buy for high

resolution screen printing on substrates

like metal and glass let's start off by

talking about the screen itself if

you're like me you're probably pretty

concerned with getting the highest

resolution possible and when you start

searching for screens you'll notice that

the thread counts are one of the main

parameters there so this is a 160 screen

it has 160 openings

per inch and this is a 350 screen 350

openings per inch and you might assume

that if you want really high-resolution

printing you should just get the highest

mesh count screen you can find and

that's sort of true but there's actually

more going on here then you might think

the photosensitive layer actually has

some thickness to it I can actually

catch my finger on the edge of this

photosensitive material that we coated

on to the screen and the thing that

actually determines the shape that

you're going to print is in fact this

layer so basically what I'm saying is

that this photosensitive layer can

partially occlude one of the openings in

the screen so the screen resolution is

not really like a pixel count don't

think of it like digital imaging where

if you have more pixels that's great

because your image won't be as pixelated

it really doesn't work that way it's

much more of an analog process

especially because it's really the

photosensitive layer that determines

your ultimate resolution having said

that generally yeah you need to have a

really fine support structure because

the strength of this photosensitive

layer is not that high so if you have

really fine details you kind of need a

fine screen but don't think that it's

like a one to one pixel relationship

when this process was first invented the

screens were all made of silk hence the

term silk screening but oh that's all

polyester these days even though we

still use the term silk screen in a lot

of cases just keep in mind it's an

antique term even though everything is

polyester now you can buy polyester

screen on rolls and stretch it over a

frame yourself or you can buy these pre

stretch frames which I would strongly

recommend if you're getting started

another thing you might find surprising

is that these pre stretched frames are

all very large like common sizes are

like 20 by 30 inches about and if you

only want to print small stuff you might

think well I don't need that I only need

a small frame like this however you can

only use the central about 70% of the

screen even this is about as close to

the edge as you can get because in in

the process of printing you actually

have to stretch the screen that's really

a normal part of the printing process

and you can't stretch the screen if

printing all the way to the edge so

really it's important to only use the

center 70 or 80 percent of the screen

you'll also notice that some of the

screens are white and some of them are

yellow what's the deal with that the

yellow is the dye that they add to the

polyester that they call an anti

halation technique and so if you want

high resolution when we're shining

ultraviolet light in here to expose the

photopolymer what we don't want to

happen is the light to go through the

layer and then bounce off of the white

screen and then expose the neighboring

areas so the yellow dye basically

absorbs the ultraviolet light so that we

don't get reflections and hence lower

resolution you'll pretty much find that

all of the screens above 200 or 250

openings per inch automatically come

stained yellow like this and it's just a

the only reason that these are not

yellow that all screens aren't yellow is

just a safe money so in the lower

resolution screens it's white just to

save money one reason not to use the

highest mesh count screen you can get is

that it passes less ink than larger

screens so these two were printed same

process same artwork same everything but

the print on the right was made with the

350 count screen and the print on the

left was made with the 250 count screen

and you can see that there's not quite

as much coverage here but I was able to

do it here so it's one of these things

where the higher mesh count screen is

more sensitive to technique and loading

and the type of ink and the viscosity

and everything and so the reason that

screens above 305 or 350 are super

uncommon is because they're just more

difficult to use so you generally want

to stick to the 250 to 300 range and you

get more consistent results okay so

we've got our screen picked out I happen

to like 250 to 300 openings per inch and

this is like an 11 by 17 inch

pre-stretched frame that I've had pretty

good luck with so the next step is to

coat this with the photosensitive layer

and traditionally this was done with

something called a scoop coder

and what you do is pour this

photosensitive liquid into the scoop

coder and then tip it up here and

distribute it on to the screen and

there's all kinds of different

techniques you know from one side and

then the other and then you turn it

around and wipe it again and there's

quite a bit of skill involved with

managing the scoop coder depending how

viscous your stuff is and how often you

wipe it and then you have to let it dry

of course and the orientation in which

the screen is held is important is it

face down as it face up this way and to

be honest the whole thing is actually

really difficult and I don't recommend

doing this there's a much easier way

instead of pouring this liquid

photosensitive layer into the scoop

coder they sell photo emulsion already

in a sheet on like a plastic backing and

what we do is wet down the screen with

some water and then unfurl this layer of

photosensitive material onto the front

of the screen and then just quickly use

a squeegee to brush off the excess water

and give it a little bit of pressure the

screen can be dried in any orientation

and it will dry more quickly than this

old-fashioned liquid photo polymer and

you will have a much more consistent

layer so remember I was saying what the

resolution is a largely determined by

the consistency of your photo polymer

and as you can imagine trying to get

like a perfectly you know within 10

micron consistent layer of stuff on

there with this hand process it's kind

of iffy so it's really much better to

use a premade film and just be done with

it and you get this perfectly smooth

photo polymer layer one thing is that

there's about 10 or 15 different common

kinds of photo polymer this is called

the emulsion in screen printing lingo

and you'll be overwhelmed with the

number of options available to you

there's a lot of terminology some of

these are called dyes Oh some of them

are who knows what else

dual-action or whatever in my experience

with my limited experience it doesn't

make as huge of a difference

as you might think they're really sort

of squeezing out the last bit of

performance from a screen printing

process and if you're just getting

started pretty much any of them will

work just to get your feet wet with the

process I'll of course put my favorite

list of things that worked for me in the

description well it's true that all of

these chemicals are photosensitive you

don't want to work in sunlight of course

they're really not that sensitive don't

think of them like photographic papers

or films your safe light conditions

really don't have to be that amazing and

what I'm using is generally just a an

LED like warm white LED bulb in my

garage here and I don't cover the

windows up or anything it doesn't make

any difference when you see later on the

exposure times are on the order of like

10 minutes being full blasted by an

ultraviolet lamp and so a little bit of

room light isn't going to hurt anything

even like standard you know computer

monitors spraying out a little stray

light it's no big deal however if the

screen has to dry for a day or two even

that can't happen in the room because

that's too many hours of exposure even

with a dim light so you need to have

somewhere dark to dry these things out

and I'm using this metal filing cabinet

and it's not ventilated of course so

what I do is put all the screens in the

upper drawer and then open the lower

drawer and aim a fan in there to get

some fresh air in and the way the metal

drawers are constructed there's a pretty

good light baffling it's pretty cold and

rainy here right now so the drying times

are quite long I was noticing that it

takes almost a full 24 hours for this

green film to dry and even longer for

the pink liquid that I applied with the

scoop coder

again I don't recommend doing that but I

was trying a whole bunch of different

things out while the screens are drying

you want to get your artwork ready for

printing and at first you might think

you have to use transparencies like this

but this actually doesn't work that well

because the ink doesn't stick to this

smooth surface a better solution is to

use this translucent vellum paper

and you might think that it has to be

transparent for the light to get through

but actually this passes more

ultraviolet light than this clear

plastic does I've measured it myself and

so there's basically no reason you ever

want to use a transparency like this

just go with the thick vellum paper you

can use plain old tracing paper the only

downside is that it tends to jam in the

printer it will make little creases and

wrinkles and those will actually affect

you in a bad way so the best thing that

I've found is relatively thick and heavy

vellum paper regarding the printer

itself I'm using a 600 dpi laser printer

nothing too special about it you can use

an inkjet printer of course but don't be

don't assume that that magic 4800 dpi

number they always throw around really

means anything the black resolution of a

inkjet printer is probably 600 or maybe

1200 but probably not higher than that

and as you can imagine the manufacturers

really like to stretch the numbers as

much as they can so for the most part

600 dpi is what you're going to be

printing the main thing that you want to

focus on is contrast you really want the

dark areas to be it's absolutely dark as

possible so that when you expose your

screen you get the biggest contrast

between the dark and the light areas so

if there's a density adjustment on your

printing software you want to crank it

up as high as possible okay so now that

we've got our artwork printed and our

screen coated with the photopolymer and

dry it it's time to make the exposure so

I am using this ultraviolet light source

and this works pretty well but it's not

ideal which I'll explain why in a minute

anyway the way this works is to put the

artwork print side up and then take the

screen that has the photopolymer on the

surface and put it facedown and this

will in fact create a mirror image on

there but that's fine because then when

we print this back onto the substrate it

mirrors it again so you end up with the

correct image and you know if you don't

have one of these ultraviolet light

sources it's no big deal it's really

just a bunch of fluorescent tubes in

there and the tubes are in fact special

but they aren't that hard to get it's

just

ultraviolet fluorescent tubes and so you

could build one of these but if you

don't want to build one and don't have

one you can actually use the Sun itself

the Sun is a great ultraviolet light

source and in that case what you want to

do is have a compliant backing like this

cube of foam and put your screen on top

of that and then the artwork face down

onto the photosensitive layer and then

critically you have to use a piece of

glass to force the the printed layer the

artwork flat down onto the surface and

you have to apply a lot of pressure I

mean really build a fixture to hold this

down by far the most critical part of

the entire screen printing process is

getting the artwork in really good

contact with the photosensitive layer if

you want to capture details that are a

hundred microns or a couple hundred

microns if you're off the surface by a

couple hundred microns the shadow caused

by that it's going to swamp out your

detail really this really is the most

critical part of the whole process the

sunlight is pretty variable of course

and so if you want to do this indoors

with more repeatability you can use a

mercury vapour or metal halide lamp you

can probably hack one out of an old

computer projector or just buy a mercury

vapour lamp from the hardware store if

they still have them but the point is

that the the nice thing about that sort

of a light source is that it's basically

almost a point light source and so if

you set up the lamp four feet away from

this setup when the light shines down

here even if there is a slight air gap

or whatever in there the shadow will be

very sharp and so all of the really

professional screen printing machines in

fact do use metal halide or mercury

vapour lamps for this reason the problem

with the fluorescent tubes is that the

light is coming from this extended

source so that if there is a slight gap

between the artwork and the

photosensitive layer it really will

cause a much bigger problem so to get

around this what I had been doing is put

this down here you don't need a piece of

glass for this method of course the

glass is already on the surface here we

put the artwork here and then I put the

foam layer here and put some weight on

here and I found out that I was using a

drill press vise and that was in fact

not heavy enough so I upgraded my weight

so that this foam was really compressed

down can't stress enough how important

it is to make sure everything is super

compressed together if it isn't you end

up with problems like this where you

might think there was some other issue

here but the problem was that the edge

contrast was lost because there was in

fact a slight air gap with this set up

with the fluorescent tubes my exposures

were about 10 minutes for this setup

that includes the attenuation through

that translucent vellum paper and the

sensitivity of the photopolymer

everything when I was using that pink

photopolymer that I applied with the

scoop coated the exposure times were on

the order of two minutes so your exact

setup your exact chemicals the

attenuation of your paper that you're

using or the transparency that you're

using wall effect the exposure time so

it's kind of tough to give an exact

value luckily it's pretty easy to figure

out and also if your exposure is 10

minutes being plus or minus you know 20

seconds doesn't make a big of a deal so

you don't need a timer or as a fancy

darkroom timer because these exposure

times are so long after the exposure is

complete you want to wash away all the

parts of the photopolymer that we're not

cured by the UV light and you still have

to do this under you know quote darkroom

conditions but I did it in my kitchen a

few times and it's fine even with normal

room lighting it's not that big of a

deal just because it isn't that

sensitive and normal room lighting

doesn't output that much UV light you

can also do it outdoors at dusk or

something with a garden hose that works

fine too

you don't need a pressure washer to do

this step at all especially if you're

using a film emulsion that doesn't

really soak into the mesh as much as the

scoop KOTOR method does later on it's

helpful to have a pressure washer to

clean a screen that is very stubborn

especially ace

Green that has been used with these

epoxy inks or epoxy paints that are very

sticky and hard to get off but the clean

out of the of the photopolymer layers is

relatively easy it's okay to use a brush

to clean out stubborn areas and you

might be surprised at how much of a

manual process this is use cool water

you don't have to add anything to the

water to clean out the photopolymer but

it is true that using a soft bristle

brush can make the process happen more

quickly and also you can kind of focus

on areas that need a little bit more

cleaning

now that the screen is washed out and

dried it's time to print this process is

pretty straightforward the only thing to

note is that the screen should not come

down into contact with the substrate

that's a big problem

you have to suspend the screen above the

substrate and then when you come through

with the squeegee it actually pushes the

screen down into momentary contact this

is super critical if the screen is

allowed to come into contact with the

substrate for too long the ink will wick

out under the covered areas on the

screen and you'll end up with a really

poor resolution image the standoff

distance doesn't appear to be that

critical I was just using a couple

pieces that may be you know five or six

millimeter thick acrylic and as long as

you can easily push the screen down

without feeling like you're stressing

anything it's probably fine the choice

of ink though is another interesting

thing the fact that you can use any ink

you want with screen printing is one of

its main benefits right I mean you can

use conductive inks or

electroluminescent inks or anything

under the Sun but if you use a

purpose-built screen printing ink you'll

definitely get the best results and

again if you're just starting out it's

kind of nice to start with something

that works so well one thing that was

new to me was the use of these epoxy

paints so you can see here on the right

this is a black two-part epoxy paint and

the performance is just absolutely

incredible you can see the density these

were all printed with the same screen

the same process the same substrate

glass this is sort of a medium quality

black enamel and oil-based paint this is

actually an undiluted artist's oil paint

so this is not really the same thing

because this is a carried in a solvent

base this is actually drying by

oxidation that it's very dense but the

epoxy paint is still better it leaves a

really nice finish the adhesion is super

high the density is really nice the only

downside is that cleaning up this epoxy

paint is a super nightmare there's a

special cleaner that you can buy from

the screen print places that will help

you clean it up but it's really a whole

other level of pain like if you think

that cleaning up oil-based paints is

difficult just wait until you clean up

an epoxy based paint the only reason you

use them is because the performance is

really that amazing once they're dried

they're solvent resistant and fade

resistant I mean they're really really

nice paints this cleaner is pretty

aggressive and if you let it set on the

emulsion for too long it will actually

hurt the emulsion so you have to be

pretty quick at cleaning the ink out

with this if you're using an oil base or

a water-based paint just use water or

naphtha to clean your screen if you're

using the epoxy based paints you pretty

much have to use this because I haven't

seen anything else that will clean up

those epoxy paints when you're

completely done with a design and want

to print something else it's not really

economically feasible to throw the whole

screen out so then you use this chemical

to loosen the emulsion and spray it away

with a garden hose or in a sink and this

works pretty well I've never had much of

a problem getting rid of the film

coating cleaning off the pink stuff that

I applied with the scoop coder again was

more difficult so you saved time on both

the front and the back end when using

this film process and then as a final

cleaning process after the emulsion has

been removed you can use this stain

remover and degreaser which is basically

soapy water with maybe like pumice

powder in it or something it does

roughing up the screen a little bit

which is great because that provides

adhesion for the next emulsion you're

going to put on there and the degreaser

is important so that you get a nice

clean sheet of water on there

which helps the emulsion stick as well

so with everything I've shown in the

video you can easily get down to 400

degrees and 300 micron pitch eight-point

font looks pretty good Sixpoint is

marginal and anything less than that

doesn't appear to work and you can see

with a side by side with the original

artwork my printer can print 200 micron

pitch and easily get down to six point

and maybe even four point font so

there's a little bit of loss going from

the print to the or from the printed

artwork to the screen printed but with a

little bit of tweaking and a little bit

more care I think it can actually make

it as good as a laser print in terms of

resolution but anyway they're really the

strength of screen printing of course is

that you don't have to use ink from a

printer you can use all these other

weird things and you can print on

substrates that you could never feed

through a printer anyway I hope that was

helpful and as always feel free to put

your questions in the comments and I

will see you next time byeearn money online without investment for students, earn money by clicking ads, earn money online without investment, online earn money website, online jobs to earn money, best online income site, top 10 online money earning sites, easy income online, easy online earning, earn money online from home, make money online legit, earn money online free fast and easy, online earning websites list, genuine online money earning sites, online work to earn money, online surveys to earn money, earn money through internet, best online income, earn money online data entry, easy ways to make money online, best online earning websites