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Category: Contact Printing Frames

All about contact printing frames.

Troubleshooting Hints

If you are having a hard time getting the results you expect from your printing efforts and suspect that your contact printing frame may be a part of the problem, here are some ideas that may help. Keep in mind that I’m not an expert printer, but I do have some education and a little experience in the craft. I’m happy to help any way I can.

I appreciate comments on any of my posts, but if you have a specific question you’re probably better off using the contact form since I watch my email more closely than the comments.

The Frame

Well, it’s not rocket science. The four legs of the printing frame make up the basic structure and are what holds everything together. My frames are made of hardwood held together with finger joints and hardwood dowel pins at the corners. It is unlikely the frame itself will ever fail.

Glass

I use non glare glass in all my frames since about 2010. It is intended to reduce the occurrence of Newton’s rings.

“Newton’s rings is a phenomenon in which an interference pattern is created by the reflection of light between two surfaces—a spherical surface and an adjacent touching flat surface. It is named for Isaac Newton, who first studied the effect in 1717.” Wikipedia

Non-glare glass must be installed so that the etched side is facing the interior of the frame. That is, the etched side of the glass must be in contact with the non-emulsion side of the negative. If you can’t tell which side of the glass is the etched side, look at a reflection in it. One side will show a clear reflection, while the etched side will show a very dull reflection. If the glass is placed in the frame upside-down, your print will not look sharp.

It is also important that your negative is placed correctly in the printing frame too. The ink side ( we used to refer to this as the emulsion side) of the negative should contact the printing paper. Again, if the negative is upside-down your print will not be as sharp.

Split Back Springs Feel Loose

If the back feels loose here is how you can do the tighten up. I attach the springs using a screw instead of a rivet like some other frames. Like everything this has its upside and downside. The upside is you can remove the springs and give them a nice polish with a little Brasso or other metal cleaner, assuming of course you have brass springs. Wooden springs can be cleaned up with a light sanding. Downside? Yes, the screws can get loose and make the frame feel a litttle woogity. The fix is easy. You don’t even need a screwdriver. Just spin the spring clockwise till the screw is tight again.

Broken Glass

Glass can break – duh. If you experience this misfortune, don’t despair, but be careful picking up the pieces. I can replace your glass with the original non-glass type I used when I made the frame or you can obtain replacement glass from a local provider. I recommend 2.3mm (1/16″) non-glare picture frame glass. Other dimensions vary with the size of frame. Best bet is to take the frame to the glass shop and ask for a piece that fits easily in the frame. Also has smooth edges so you don’t get cut when you remove the glass for cleaning.

If you have to order a replacement from me (or anyone else), please send the exact inside dimensions to the nearest 1/32″ of the frames width and length when ordering. Include your address and I’ll give you a quote including price and shipping.

Normal Wear and Tear

I think it would take a lot of work to wear the finish off of one of my printing frames. However there is one place that will show wear before any other. That is where the springs rub against the back when locking it in place. To repair the rub marks, remove the back from the frame and remove the springs from the back. Use 120 to 320 grit sandpaper to prepare the surface and apply two or three coats of Minwax High Gloss Polyurethane varnish. For best results allow varnish to dry completely and sand lightly or buff with 00 steel wool between coats. Reassemble springs and enjoy. Note: Don’t remove hinges unless absolutely necessary since the threads made by wood screws can be stripped easily.

Distance and Exposure

The distance from the light source to your print is important when determining exposure time. I mounted my 20W UVLED exposure unit under the lens holder on my Minolta enlarger so I can easily adjust the height. I can move it up to cover a large print and down for a small one. The advantage of moving the light closer to the print is reduced exposure time. But just how much should I reduce the exposure time, you might ask. Well, here’s how to figure it out. It’s based on the principle that the intensity of light is proportional to the square of its distance from the subject. The inverse square law, IL=1/D2 applies here but keep in mind it’s relative.

For example, if your light is 10 inches from your print it would have 1/100th the intensity as if it were 1 inch away. That’s pretty simple but what happens when we have to deal with real world measurements. Let’s say you were exposing a print with the light source 18.5 inches above the print and you measured the standard exposure at that distance to be 68 minutes. Then you realize that you don’t need to cover such a wide area and you can move the light closer to the print. It looks like you’re getting pretty good illumination when the light is only 11 inches above the print, so how much is the new exposure time? We’ll calculate the exposure factor, a value we’ll call EF, by which you can divide the original exposure time to obtain the new exposure time.

Formula: EF = E12 / E22

Where: EF is the exposure factor, E1 is your original distance and E2 is the new distance

E1: 18.52 = 342.25
E2: 112 = 121
EF = 342.25 / 121 = 2.83

Divide the original exposure time (68 min) by 2.83. That’s about 24 min. See you just saved yourself a bunch of time. If you’re moving the light source away from the print, simply multiply the original exposure time by the exposure factor instead of dividing.

The Pin Register Project

Pin registration is a method of precisely aligning  negatives to the paper (or other print media). It is used by alt process enthusiasts for aligning color separation negatives for multi-color prints (gum bichromate), or to make multiple exposures of the same negative to increase contrast (platinum/palladium).

My pin registration hardware design began as an exoensive solid brass alignment strip with  brass pins and a modified office punch set to match the spacing of the registration pins.

I started working on the pin register project over a year ago with the help of Christopher James who has been using a prototype of this frame in his Alternative Processes workshops. Even though testing went fairly well, keeping the punch spacing fixed was a problem. Now a new design eliminates this problem and the need for a clumsy office punch altogether.