Can anybody recommend a film to print positives onto?

[Alan Drury]

Try DEP on 01737 813517, speak to Fiona. I produce artwork for a packaging tape printing company (flexoprinting) and we have had considerable success printing on to their film with an ordinary Epson inkjet and after market inks and then producing the block from that. Prints very black once the driver settings are correct (use black only) we have also found that we get a blacker black printing directly from Corel rather than producing a pdf first.
Alan D

[Steve Underhill]

How complicated is the design?
If its not microscopic we use black T shirt flex, it is totally opaque and as opposed to using something like sign vinyl where you have to stick it directly to the emulsion, it lifts right off after exposure as its on a carrier sheet.
If its a really complicated design we used to print 2 laser copies onto acetate line them up and tape them together so it was black enough, you can buy density toner as well for making the ink blacker, it bonds the particles together more closely or something i read.
For short runs we stick oracal 651 directly onto the screen, no exposing needed and it lifts right off afterwards, dont bother using paint mask, it isnt sticky enough to stick to the mesh.

[Steve Morgan]

Thanks for the tips, I realised that I could of course I could just cut black vinyl and put that onto acetate. Hadn’t thought of using flex material or putting cut vinyl straight onto the screen

Steve

[Steve Underhill]

What sort of ink are you using, I assume water based, I can tell you that the vinyl has a very limited life using plastisol as it starts to buckle around the edges due to the reducer, but water based should last longer.
but the T shirt vinyl although not as cheap as calendered vinyl is an excellent way to get finer detail and you don’t have to apply app tape and take ages rolling it back off so as not to lift the vinyl, just mask it off and expose.
Job done

[Steve Morgan]

We’ll be using a solvent based ink as it’s onto vinyl. I think for speed I’m going to cut the job in black vinyl and put that down onto some acetate and make the posi from that. It might be useful to have the original to keep.

Steve

[Richard]

If the design is cuttable, use Rubylith or something similar, it’s available from Metamark and Spandex (and probably other places too).

It’s a VERY thin red membrane coated onto a stable polyester carrier.

Cuts and weeds a dream.

[Steve Underhill]

Its about £130 a roll though isn’t it?
I looked into ruby film, but it was so expensive unless you make thousands of exposures it wasn’t worth it as you couldn’t buy like 5m lengths.
If you can that’s the stuff to use, but I haven’t found it in short lengths yet.

[Fred McLean]

APA do a black stencil film it’s brill 😀
5m minimum rolls

[Richard]

Metamark and Spendex both sell by the metre.

The per metre price goes up, but you don’t have to commit to so much.

It’s much mre user friendly than the black if you have mutiple colour jobs to plan because it is transparent.

[Nicola McIntosh]

i just use scrap vinyl…..if you have a good light source, doesnt matter what colour your vinyl is…but for smaller text i use 7 series in black, gives a nice sharp print 😀

nik

[Steve Underhill]

Im going to start using a black biro.
The 5m lengths sound good so will have to look into that.
Im also going to have to use a lot of acetate as some of my designs are photographic quality so Im not going to be weeidng for 3 weeks.

[John Gregson]

Hi all,
I’ve got a minolta 2300DL laser printer that prints out perfect acetates that I use as posy’s for screen printing. The black is very black and you can’t see through it or expose through it no matter how long you leave it under the lights. There is a special setting on the 2300 that allows for acetates, it slows the printer down and drops loads of toner onto the acetate to make them jet black. Shame its only A4

Minolta laser 2300DL approx £50 – £100
Conquerer acetates approx £5 per 50 sheets
both of above second hand on ebay.

If buying second hand watch out for marks on paper prints and check the fuser unit and consumables print out page.

Cheers John

[Gert du Preez]

If you are going to print onto vinyl, using Rubylith or Vinyl as your stencill will not work. The reducer of the saffire ink will dissolve the rubylith, and also vinyl wont last 2 pulls. Works OK for textile printing wich has water based inks. There is a product similar to ruby witch is water solluble, i.e. for use with solvents. (it looks like rubylith, but is orange iso red) Used some many years ago. Sorry, dont even know the name!! If your design allows it, cut posis from ruby, and expose your screens. You can also try using ozatex on you laser, but it stretches with the heat, so no good for tight registration. Have posis made at a litho printer. It costs next to nothing, and you’ll get the real deal!!

[Steve Underhill]

quote :

The reducer of the saffire ink will dissolve the rubylith, and also vinyl wont last 2 pulls. Works OK for textile printing wich has water based inks

oracal 651 lasts, I used it to print about 30 shirts a couple of weeks ago, just for some demo shirts and they were fine, and I was using plastisol ink.
But you cant beat making a proper stencil.

[mark browne]

mod-edit 1 please read board rules advertising is not permitted

[Ian Stewart-Koster]

3M cast vinyl- series 7725 is easy to plot, easy to weed, and has a clear plastic backing- it works well.

We do everything but single-print fabric jobs with photographic stencils- the positives are made sometimes with laser vellum, sometimes wide format tracing paper & opaque ink, with the HP 650. Registration is OK if you pre-plan.
You can also get a proper screen film which is best-lovely quality- but it’s not cheap.

[Steve Underhill]

You mean the ruby lith film?
Depending on your design if it isnt majorly detailed you can just expose with black T shirt vinyl on the emulsion, nothing sticks to it, and its perfectly opaque.
However you can get very fine detail in T shirt vinyl, far more than sign vinyl.

[Ian Stewart-Koster]

Hi, no I don’t mean rubylith film.

In the essence of helping to make it clearer for others reading this in the future, I’ll explain:

Rubylith is dark red gelatinous film, on a clear acetate-type backing. This semitransparent film is light-proof to UV light, and can be handcut & weeded or plotter-cut & weeded, then it is used as a positive, to expose UV-sensitive emulsion. It will hold very small letters, and great precision, but it is a pain to weed small stuff. It is a good product.

We have an orangey product available downunder in Oz, called Amberlith- some call it autotype, I think.
It is a similar gelatinous product that can be hand or plotter-cut, but it is waterbased, i.e. it will stick to the underside of a screen with a light misting of water. It is also carried on a clear acetate-type of sheet. Being waterbased, you can use it to make a ‘negative’, in reverse, which you stick under the screen, and you can print corroplas/corflute ink, or vinyl ink, and I guess you can print plastisols through it, but I don’t use plastisols- we use waterbased fabric inks- which will dissolve that amberlith if tried. The amberlith easily comes off the screen after a soaking in water.

We have a greenish transparent film on a clear backing- also sometimes called autotype I think, which is lacquer-based- i.e. you use lacquer thinners to adhere it to the underside of the screen & when dry, peel the clear carrier sheet off- then you can print using waterbased inks.

In USA, and some other places, the green film is the waterbased stuff, and I don’t know what colour their lacquerbased stuff is.

I find the lacquerbased film a real pain to remove from screens, and would rather use a photosensitive emulsion than use the green lacquer plottable film.

None of those films are ‘cheap’ though.

For a real cheap quickie stencil if printing with waterbased fabric inkl, you can cut the image in reverse in a plotter from any thick vinyl, and stick it to the underside of a screen & get 20-30 prints from that OK, if the image is a simple one (i.e. no halftones)

Another cheap quickie way is to plot the text as a positive in ordinary cheap vinyl, and stick it to the squeegee side of the screen, i.e. inside, thrn coat the screen over that, with liquid screen blockout, then when dry pull the letters off. Use waterbased blockout if printing corro or vinyl, and lacquer based blockout if using waterbased inks.

I still find it easier to just coat with emulsion & UV burn a screen.

The proper screen positive films are the best- they’re a milky clear film that will go through most inkjet plotters made for the job- eg epson 3000 & newer ones.

We’ve tried bond paper as a positive- not good- too opaque.
Translucent bond paper- works OK- takes a little while to expose, compared with clear film, but otherwise it’s OK.
Tracing paper works better- but check what brand & kind- you need a drafting/architectural stiff one, not something that will buckle from the moisture in the inks.
Laser vellum works well for single colour stuff- but can give shrinkage & registration issues for multicolour stuff, though these problems can be overcome. They only work for stencils or positives that you can fit on a sheet of paper the right size for your laser printer.
It really does help to spray it with toner darkener though.
Laser clear OHP acetate works also, but getting a dense enough black is difficult-possible, but difficult. You need to not use the OHP setting in the printer driver, but frequently a cardboard-type of media printer setting lays down more black.

It all depends on how you value your time- the better equipment costs more, but performs far more efficiently.

We mostly use an old HP-designjet-650C which will print 3 ft wide, and prints an opaque black ink, asopposed to a transparent black dye like most inkjet printers. It gives us positives the right size for 3 x 2 ft corro signs which we do a fair few of, and it gives us fair halftoned positives also
but only by halftoning via ghostscript, or via photoshop, as the postscript drivers for the hp650 are ’emulation’ rather than real, and don’t give you lpi/freq. & angle & dot shape control.

This way is cheap/economical/efficient/quick for us, for what we do- it won’t necessarily suit others. If I need a really high class halftoned positive, I outsource it to a company nearby who have an epson 9000 or something like that, and the proper film & a proper RIP.

…and yes, you can use thin heat-press T-shirt videoflex/thermoflex plotter stuff too- which will hold small letters well- but it takes me less time to switch the hp printer on & send the file to print & wait for it to dry, than it does to put the t-shirt stuff in a plotter & weed small letters and then try & lift the edges with a pair of tweezers & stretch them off the backing- I gave up that idea a few years ago- all of the laser printer options were better (more efficient, timewise & material-wise), in my opinion.

Then you have to expose the positive- after of course calibrating the various different materials you’re using with their different degrees of transparency. You can use the sun’s light, or various arc-lamps, or various uv-tubes or halogen lamps- all have different levels & light spectrums & exposure times- you’ll have to work it out yourself. Even the sun has different intensity levels depending on the season & time of day.

We used the sun for years, till we had 2 weeks’ cloud & fog & I could not expose a single screen, and needed a dozen, so we bought an old UV carbon-rod arclamp which puts out a welding-type of spark, and exposes as fast as the sun does, clearly & well- 25 seconds is about perfect for most clear films & tracing paper, at 2 ft 6" distance. For vellum, add 3 minutes to that. Increase the exposure distance by 8", and you need to almost double the time.

. You can hold the positive in place with gravity & a piece of glass, or with g-clamps & a piece of glass, or a vacuum exposure unit, which is so much better than the others you can not believe, till you’ve tried it.
You can have vertical units, and horizontal units with the light underneath, or the light on top.

Hope that helps!

Now if using Ghostscript to produce a halftone- that’ll take a bit more to explain- it’s a bit of a learning curve, but free ad very good for the time it takes as long as you don’t forget how to do it, in between uses. Photoshop’s bitmap halftone conversions are excellent, if you have photoshop. I won’t explain that here.

(P.S. I am no expert, just an inquisitive amateur who’s done a lot!- we print about 50-100 corro signs a month, in batches of 30 to 50, for elections & other functions, and we do shirts for many local schools & kindergartens, and show-ribbons for a few local agricultural shows, and vinyl stickers for some machinery manufacturers who wanted stuff in colours not available in vinyl, and cheaper than in vinyl, and longer-lasting than digital prints)

[David_Evans]

Grafityp do the ruby film but not sure what there min order is.

Dave

[Chris Wool]

thanks for typing that lot Ian very informative.

chris

[Nicola McIntosh]

nicely explained ian….and at the end of the day it all really depends on the individuals equipment experience, and most importantly costs, emulsion is the best at lasting with the inks and cleaning, it lasts far longer than the really expensive autoptye film, a roll in comparison was over £200 (years ago) compared to emulsion which was just over £50 for a 5 litre tub and lasted far longer….and it didnt produce the ‘crispy stencil’ syndrome with the staff, who always wasted rolls of film doing so 😀

nik

[Glenn Sharp]

I didn’t realise that Amberlith could be used as a stencil……..

I take it you just gently dry it off to enable you to get the clear carrier off?

How many prints would you get from an Amberlith stencil on average…are they robust or just for short runs?

[John Gregson]

I was brought up on 5 star which was fantastic and gave very sharp results, if used correctly, but really expensive. We moved onto emulsion as its cheaper and on textiles a stencil will last forever. 😀
John

[Ian Stewart-Koster]

The last time we used amberlith- the waterbased adhering stuff- we plotted it & stuck it on the bottom of the screen with water. When thoroughly stuck on & dry, you can peel the carrier off.
We did 100 four-coloured corflute/corroplas real estate signs with no problems, though you have to watch the centres of any really small letters in case the pressure slowly pushes them off.

As Nicola says, photosensitive emulsion is cheaper & easier, if you have the means to make positives & expose it. We use a dual-purpose stuff for everything nowadays.

[David Rowland]

Steve, I not read this thread. I am pretty certain I glanced out quite a few film positives at Fespa coming out of printers like versacams. I cant be sure of which ink/media they were using.

[Steve Underhill]

I agree,
Stencil emulsion is far easier and longer lasting.
If our laser wont print black enough and the design isnt too complicated I just print 2 acetates and stick them together to make one very dark one, that works.
I havent tried density toner spray yet I may give it a go.
I just bought a new 1 colour press to do transfers with so will be having a play this week.

[Duncan Wilkie]

We use a Ulano product called autocut amba. It is a water soluble stencil film that we cut on the plotter, then adhere to the screen.
For our photo screens, we use their UP3. No chemicals needed to develop the film.
There is some good info on their website.

http://www.ulano.com/

[Neil Churchman]

Answering the original question…….

We use 3M OHP film in an Epson printer set to best photo quality and paper set to Matte Paper.

Nice crisp solid black positives and easier than running a darkroom.

The 3M file is available from Staples

[Richard Sild]

I use an A3 b&w laser printer for smaller posi films.

The film I use is a laser film double matt 75 micron.
http://www.colenso.co.uk/digital-media.htm

After its printed out, wipe white spirit over the printed area and dry with heat gun to make the black really dense.
a box of 50 A3 sheets is around £35.00

Works a treat.

[Nicola McIntosh]

quote Richard Sild:

I use an A3 b&w laser printer for smaller posi films.
The film I use is a laser film double matt 75 micron.
After its printed out, wipe white spirit over the printed area and dry with heat gun to make the black really dense.
a box of 50 A3 sheets is around £35.00
Works a treat.

same way i do small positives too…but i find rubbing with turps makes no difference to the density of posi 😕

nik

[Steve Underhill]

How about density toner spray?
has anyone tried that?
I saw a video of it working and it seemed to be very good, but its £15 a can and a bit of an expensive gimmick if its not very good.

[Nicola McIntosh]

quote Steve Underhill:

How about density toner spray?
has anyone tried that?
I saw a video of it working and it seemed to be very good, but its £15 a can and a bit of an expensive gimmick if its not very good.

i use it…..it does make it darker, well more shinier, so it makes out the positive is darker 😕 i just love the smell of it 😀

nik

[Steve Underhill]

quote Nicola Rowlands:

quote Steve Underhill:

How about density toner spray?
has anyone tried that?
I saw a video of it working and it seemed to be very good, but its £15 a can and a bit of an expensive gimmick if its not very good.

i use it…..it does make it darker, well more shinier, so it makes out the positive is darker 😕 i just love the smell of it 😀

nik

Good enough for me, Ill get some
Thanks Nik
Steve