UV Exposure Box for Polymer Plates

Once I had multiple letterpress printers and learned how to letterpress with polymer  the missing element was a way to expose plates myself so I can be more spontaneous. I've done research for years and almost bought an exposure unit but couldn't decide which kind. In the end my DIY urge took over. I always think, "Why, I could make that!"  Sometimes I'm too optimistic--we won't talk about the vacuum frame I made some years ago to use with my previous exposure unit made of a Home Depot work light with the UV protection screen removed mounted on a discarded darkroom easel. The worklight did emit UV but not strong enough so although I sometimes succeeded it was more luck than reliability.  Also heat would really build up and that didn't seem good for the plate material.   Now I was ready to do a more professional attempt at an exposure unit.

My hopes were to use it for exposing Solarplate, letterpress plates like the ones from Boxcar Press, and Imagon which was my first love. Advice varies from guru to guru. Keith Howard says you HAVE to have a point light source and that fluorescent bounces all around and I guess gets under your negative/transparency.   I can't afford those lights and they scare me a little bit so on to Plan B. It seems that many people are doing well with black lights. In Dan Weldon's book on Solarplate, Printmaking in the Sun, he gives instructions for making a box but when he gets to the step of wiring it he says to find an electrician--no way I want to pay for that.  Nevertheless, I decided to forge ahead.

Home Depot was the first stop where we got the MDF for the box and had it cut to order (thanks to the nice man who  so carefully cut the pieces).   In the lighting department I wandered around feeling discouraged until I came across some fluorescent bulb units that said they could be plugged into each other in a continuous line and at the end would be a regular plug--hooray!  I think they were meant for undercounter lighting.  They were about the size (18")  I wanted for my box so I bought 8 and later went back for 2 more to make the light source wider . Then I discovered that black lights didn't come in this size at home depot. I hit the internet--it took a long time to find the right bulbs.    Bulb Town was my hero. I learned a lot about fluorescents and their obscure naming codes.  Meanwhile I built the box and waited impatiently for the black light bulbs. I painted the interior of the box black to reduce the light bouncing around. I worried that there was some other type of fluorescent black lights that I should have gotten rather than the  the straight "black light" ones I chose.

With the bulbs installed the next step was to expose some test strips to a Stouffer scale negative and see what would happen. I wasn't completely clear on what I was going for--I only knew the Stouffer value for one of my plate materials so I used that as my guide. I figured the thicker material would take longer to expose and my test strips seemed to agree.  So my exposure box worked!!

  I began to realize how valuable a timer that controls the lights would be. So far I haven't found such a device in my price range (cheap).   I don't entirely trust my test strips as I 'm not so good at timing precisely and I like to go do something else rather that stand there twiddling my thumbs.  With a timer I could relax and know it would turn off after the right amount of time.  I think the slim line bulbs put out less light so exposure takes longer than units I read about. This is ok because, unlike the work light, heat doesn't build up during a longer exposure.

At first I put the plate right on the counter and the lights were the distance of the height of the box away from the plate.  Later on I decided to put the plates closer by building up a platform within the box.  I had to cut a flap out of the side of the box so I don't have to lift the entire box.  I put two hinges on the flap so I can lift the flap, insert the plate, and secure it with a turnkey.

I'm sure professionally exposed plates are better than what I can make, but as an artist and amateur printer of books, I'm quite happy  using my homemade plates.  As an impatient  person who sometimes doesn't plan very far ahead this is the perfect system for me.  For special projects I will still rely on Boxcar Press to make my plates--they do an awesome and perfect job.

It's Boxcar Press who sell the unexposed plate material I use and the excellent adhesive sheets that are easy to attach.  I make negatives with my laser  or inkjet printer on transparency films made for those printers.  In order to get a proper density of black I print twice and carefully align and  tape the two transparencies together.   For exposure I use a photographic contact printing device  or  sometimes I make a sandwich of glass and a backing board with  the negative above the plate and either black felt or black funfoam under the plate.

 I have experimented with using a space bag as a DIY vacuum frame as shown by Cape Fear Press in their  video  My space bags have logos all over them but one day I realized that the simple solution is to have the back of the bag face up.  I haven't scientifically experimented to see if there is a difference in the two methods of exposure "frame".

Washing out the plate is a subject covered in various places on the internet.  I bought one of the expensive brushes sold by Boxcar and I highly recommend it.  I think exposure and washing out should have a separate post which I will have to work on.   I have lots of pictures of this uv exposure which I hope to add to this post soon.

I've let a lot of time go by without blogging so I'll try doing some catchup work.   I had the good luck to find a Poco Proof Press #0  on ebay which was within driving distance.  This particular press is unusual, in that it's been sandblasted to remove all the paint, leaving what looks like a nickel coating on the press.    It weighs quite a lot but my husband and I managed to get it safely into my studio.   

The first problem to be solved was figuring out how to keep the press bed from rolling right on off the tabletop.   After putting out queries and getting lots of suggestions I replaced a missing rod on the inside center of the body which projects just enough to engage with similar projections at either end of the press bed.  When the end of the press bed reaches the center projection it can't go any further because the two projections bump up against each other.  I used nuts with bolts for the center projection and for the missing end projection on the bed.   

There are also two holes in the surface of each end of the press bed which are supposed to have rods to be used as stops for locking up forms.  In those holes I used bolts with several nuts  above the bed and one nut under to tighten against.  I had to make sure the bolt wasn't too long or it would bump into the under structures of the press.  

Next I had to figure out the cylinder and packing.  That's still a work in progress but I used some davey board for bookbinding and cut it with the grain short  ( going from side to side of the press)  so that it would flex properly around the cylinder.  Over that I put a thin piece of rubber material and over that mylar.  The slotted rod which tightens the tympan was rusted and wouldn't budge but after days of using penetrating solvent it loosened,  and I was able to insert the tympan.  By that time I had corresponded with Arie K. who has the original instructions for the Poco still stuck onto his cylinder.  He kindly photographed  the cylinder  in segments and posted the photos to Flickr.  I spent some time transcribing as much as was legible.  These instructions say to insert both ends of the tympan into the same side of the slot and insert the tool (I had to improvise with a piece of rod) to tighten.  This worked perfectly!     If anyone would like a copy of the instructions I'll be happy to send them by email.  For some reason I couldn't get it to copy and paste into this post. 

I've printed one project so far--it involved type and a linoleum block.  It wasn't perfect but at least I can see the potential of the press.  I would love to try setting up some kind of registration device/system on the cylinder.  For the first project I simply eyeballed it and laid the paper over the form.   Another area to be improved is doing better hand inking.    And, of course, coming up with a name for my new friend.  Poconoo  is a possibility (get it?  poco no. 0)    Hmmm--some form of Pocohontas?  Pocohontapress?    Pocowantapress   Pocowannapress!!    Stay tuned for the winner...

New arrival--a proof press!!

Well, I couldn't let that workbench stay  empty, could I?  I spotted this proof press on ebay within driving distance (thank you, husband) and I put in a bid and  fortunately won.  Then I panicked--was this really going to print type and wood/linoleum blocks? So I used the time before pickup day to do research and quell my fears.  I focused on registration since I think that's the weak point for a simple proof press like this as opposed to some of the Vandercook proof presses.

 The sellers were very nice people--someone in the family had taught printing in a school and had a shop in the basement.  I quickly checked the press and saw I was correct that it will print type-high stuff so that was a major relief!  It is a LinoScribe proof press.  Apparently there are some LinoScribes that  print rubber type that's only made by the company but other LinoScribes are for proofing and sign printing. 

 Before even cleaning up the press I eagerly got out an assortment of cuts and type and linoleum blocks and tried it out.  Oh my gosh--it worked great!  I love the dial on the side that changes the height of the roller.  I discovered that it has a nifty mechanism to hold the paper in place that consists of a row of "fingers" which are operated by a handle held tight by a spring.  The roller mechanism opens the "fingers" by depressing the handle when it is in the farthest position to the left.   After putting the paper in place you can roll the carriage just a bit and the "fingers" close tight.    

I can see I will need to keep notes on how high the roller setting should be for different kinds of printing material.    The grid that was in the press bed was filthy and damaged so I removed the bar that holds that in place which is at the opposite end of the press from the "fingers".  I replaced it with graph paper covered by a layer of acetate.  I'm thinking I can write on the acetate maybe. Or maybe I'll want to put a grid specific to each printing job under the acetate/mylar.  

  I can see there will be a period of experimentation before I figure out the best way to deal with registration.  I've seen plans online for a frisket and tympan device but since I already have a way to secure the paper that doesn't seem like the way to go for my situation.   Maybe some strong rectangular magnets would be good to make sure my block stays where I want it when I'm in a hurry and don't want to bother with locking up the traditional way?   Always lookin' for easy street!!!   Also, magnets would hold the graph paper/acetate down at the corners.  I can't see a way to secure them at the "finger" end of the press bed.

I would love any input from experienced users of presses like this--there's just not much on the internet that I can find.