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KF 152 Curing Time

Hello everyone, I am new to letterpress and I am hoping to get some advise here.

I bought my first KF152 PP Plate and started curing under a, 4 x 9W bulb, so 36W UV Nail Lamp…Am I just kidding myself that I can use this UV lamp or I have to buy a proper exposure unit?

Thanks all!

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You are just kidding yourself.

Gerald
http://BielerPress.blogspot.com

I should clarify this. When You Tube launched a well known and respected alternative film maker was asked what he thought of it. He said it was like ants at a picnic.

The ants won. Some of my favs. Watch this moron blow up his Mustang engine. Or Russian on armored vehicle shooting 500 pumpkins.

Do you get it?

Gerald

Unfortunately, this sounds like it wont work - go ahead and try it on some scraps and see for yourself though, who knows.

Light is THE most important part of making photopolymer. I’ve made photopolymer on and actual photopolymer unit, on a screen printing (single point lightsource) machine, and in a home made unit. If the light is single point, not strong enough, or in anyway uneven you are going to have a miserable time.

I usually was forced to expose on the screen printing exposure unit which was torture (in spite of it being a vacuum sealed very expensive machine). I put kreen between the glass and the neg/plate and that helped but I still had problems all the time and small type was just unreasonable to ask of this set up.

The home made unit and the photopolymer unit both worked equally well. Note that the homemade unit I am talking about was build by someone who has been doing this for decades, but I can describe it to you, and it wasn’t expensive.

You must have rows of lights - long UV bulbs. The reason for the rows is that it causes the light to hit at multiple angles which creates a ‘shoulder’ on the exposed image ensuring it sticks properly and doesn’t wash off.

My mentor simply went to home depot bought a few long bulb units (I’m not an electrician, so don’t ask me which) and bolted them into a box. He attached a little curtain around it to keep the light in. The box was hinged on the wall so it could come down level over the type about an inch or two away. He used a true vacuum table, but he also built a portable vacuum table using pegboard. Basically a sealed frame with a slot in it and pegboard on top. You put the plate/neg on it, a sheet of kreen on that, and run a vacuum hose to the hole. So long as the kreen covers every hole and the peg board is strategically supported so it doesn’t bow inward from the vacuum pressure- it should vacuum up nice and tight.

He’s been doing this for many, many years and I’ve used his unit with great success. Make sure you have a proper photopolymer brush and rinse in warm water. Dry the plates immediately or the material will slough off. Good luck.

Also, if you’re new to letterpress, I would just suck it up and buy the plates for a while. There are a lot of variables here that could put you in a state of serious insanity trying to untangle. Unless you have a mentor that is helping you, you need to understand the press/make ready/ printing process before you can start worrying about photopolymer. Otherwise you’re going to have problems and not know which of the 93084923 steps is causing the problem.

I.e. If you have an uneven/blotchy print you may wonder… Is my roller uneven? Are they just worn down? Did I not wash the plate enough? Are the rollers clean? Do I need roller bearers? Is it the paper stock? Is my ink separating because of oil on the press? Is the temperature in the shop ok? Did I not expose the plate properly? Is the base correct? Was my time on the exposure correct? Is the adhesive uneven on the plate? Was the negative I used for the plate dark enough? Did the vacuum fail and cause a blurry image? Is the lamp warmed up enough? Did the plate accidentally get exposed? Was the photopolymer piece I used old? Did I post expose and let the plate dry long enough?

It’s enough to worry about without trying to make your own plates and then contending with all those variables. If you genuinely know what you’re doing as a printer than go ahead, but be warned.

PantheraPress

This all looks like good information. The only problem that I have noticed in the two decades since I have been monitoring the contemporary photopolymer plate biz is that there is NOT one alternative photopolymer plate processor who can clearly reveal in writing to another how to do it their way with the result that the plates come out not only perfectly useful but consistent each and every time. NEVER.

Gerald
http://BielerPress.blogspot.com

Hi all,
i’m a newbie here…I have exposed the plate for 2 mins with my 32W uv exposure unit and went for washing using warm water. The image is there but seems that there is no difference to the thickness creating the depthness. Can help and advice me? Thanks a million…

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Are you taking the cover sheet off before you expose? Looks like it is still in place.

Yes I did remove the plastic sheet before expose.

Richard:

It could be that the negative you are using doesn’t have enough density in the non-image area and you are getting some hardening of the photopolymer in those background areas.

To test, take a piece of very dense black paper or plastic film and expose a small plate scrap using it as the “image”. If the area under the black paper or film washes out, you probably don’t have enough density in your film. If you hold your film up to a strong light and pass you finger along the back of the negative, you should be able to only barely see the finger movement, if at all.

The other variable might be the age of the plate material. I have seen similar results from plates that have “passed their prime”, and are no longer useful.

John Henry

Sorry all…I have actually posted my problem in another page “Making photopolymer plates”…

Hi all masters, what’s the recommended exposure duration? My uv exposure unit is 4 X 8w tubes.

I did peeled off the protective polyester film before exposure. I tried making the plates (2 separate plates)…one by transparency film and the other by black negative film. The image with black negative film is slightly deeper but not so clear. The image with transparency film is clearer but not so deep.

Attached picture…left is the black negative film, right is transparency film.

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I operate my shop/studio/classroom on a very tight budget. As a result, I don’t send out for negatives, and have built my own exposure unit.

I have had excellent success using UV/ULTRA® II Translucent Paper run through my laser printer to make very dense negatives. The translucent paper holds more toner than any of the transparencies I tried. I picked up the paper from a local copy shop. They stock it for wedding invites and the like. I also like it for setting up registration since I can see through it.

best of luck

Other than density issues, a problem with laser or ink jet generated transparencies is the dpi rating. Imagesetters run 2400 dpi as a standard for silver-based film negatives, and can go as high as 5600 dpi. Do you need 2400 dpi? If you are at all concerned about typography or exacting replication of image, you do. If not, you don’t.

The fellows making silver-based film negatives are doing it dirt cheap these days, considering silver has doubled in value in the last five years. I’m paying 40 percent less for film than I was twenty some years ago!!! These folks are going the way of the metal type foundries, most have just thrown up their hands and quit. I’m all for supporting those who struggle to provide the better product.

Gerald
http://BielerPress.blogspot.com

Hey Gerald- Who makes your films?

Hello everyone thanks for all your input..I am now getting married and really would like to start making my own invitation cards…

Can you please help me on choosing which UV Exp Unit I should buy?

http://www.ebay.co.uk/itm/UV-Exposure-Unit-for-Hot-Foil-Pad-Printing-PCB-PVC-/300529230230?pt=LH_DefaultDomain_3&hash=item45f8f02196

http://www.ebay.co.uk/itm/UV-Exposure-Unit-for-Hot-Foil-Pad-Printing-PCB-etc-/330519732351?pt=LH_DefaultDomain_3&hash=item4cf482e07f

Thanks in advance!

Don’t blame this list for you getting married, no one told you to do that.

Priceless…