Contact Printing: Solving the Vacuum-Bag Wrinkle in Alternative Printing

Achieving good contact between a negative and light-sensitive paper is essential for making sharp, well-defined alternative process prints. Vacuum bags can provide a simple and inexpensive way to hold the negative and paper tightly together during exposure, but they can also introduce a problem: as the air is removed, the flexible bag can wrinkle or fail to press the entire surface evenly. Here is a solution.

Writer and photography / Constantinos Loumakis

This method builds on Bernd Hutschenreuther’s Vacuum-Sealed Cyanotype Printing with Leaves, and adapts the basic vacuum-bag approach but adds a few inexpensive materials inside the bag. The result is a more even, rigid contact surface that keeps the negative firmly against the coated paper during exposure, without the need for a separate vacuum frame or glass press. The setup is inexpensive, reusable, and particularly useful for workshops or anyone wanting a reliable contact-printing system at home. A fully sealed vacuum-framed print alongside, with the back side of the sealed vacuum bag holding the bubble wrap and valve.

I teach alternative photography processes, including Algorithmic Pigment Process (APP) workshops and needed a low-cost, reliable method to guarantee tight negative-to-paper contact for students, without the expense of a high-end commercial vacuum frame. Having my students make a contact negative system that they can use easily at home – and for under $30 USD (≈€28) was essential.

By using Bernd’s method and adding a few additional low-cost items inside the bag, you will now have a super tight vacuum fit for your exposures.

The Problem

Bernd Hutschenreuther’s original method article, inspired by Lothmann’s experiments – sealing the paper and negative (or leaf) directly inside a vacuum bag – works, but the article itself flags the main limitation: the bag surface isn’t flat once the air is removed. As written, the fix is to place the sealed bag inside a separate frame behind glass to press it flat during exposure — an extra step, and an extra piece of equipment. Presenting this as a classroom solution was clunky at best… so, I fixed it to work within reason.

The Solution

I modified the setup by building out the bag with a flattening surface directly into the frame bag itself, rather than treating it as an afterthought.

Materials needed:

• Vacuum-sealable bag
• Large bubble wrap – must have air gaps between bubbles to remove all air from the bag
• Plexiglass, 1/8″ thick (≈3 mm)
• Cardboard or a sheet of thick paper, placed behind the print as a wicking layer — this catches any chemical bleed-through from heavily coated prints before it reaches the plexiglass below or the bubble wrap. Warning: Do not use paper towels, as they will imprint the texture onto your print.
• A USB vacuum pump to speed the process up – found online or a hand pump model.

The plexiglass forms the rigid front surface. The bubble wrap sits directly behind it, inside the frame, so that when the bag is vacuumed down, the bubble wrap compresses evenly across the whole surface instead of just the edges pulling tight — pressing the paper and negative flat and uniformly in a single step, with no second frame-and-glass pass needed afterwards. The cardboard/paper wicking layer sits behind the print itself, preventing chemical staining on heavier coats.

Order Inside the Vacuum Bag

The order inside the bag is listed from top to bottom, looking directly downward into the bag:

1. Vacuum bag
2. Negative
3. Coated paper, emulsion side up
4. Cardboard for wicking up extra emulsion seepage if the coating is too much. Do not use paper towels, as they imprint into the paper and emulsion.
5. Plexiglass support for stiffness, larger than the print area.
6. Large bubble wrap for air extraction between the bubbles.
7. Bottom of the vacuum bag

Technique: I don’t just seal and vacuum once. I vacuum tight first, then physically stretch and tighten the bag over the negative and paper by hand to work out any remaining wrinkles, then add more vacuum pressure on top of that to get a perfect seal. I’ve found a reading of around 5″ in/Hg (≈ 17 kPa / 170 mbar) on the vacuum gauge is the sweet spot – enough to hold everything flat and in tight contact, but not so much that the negative sticks to the paper itself.

Bag Selection

This detail mattered as much as the build itself. Most vacuum storage bags sold for clothing or travel have printed branding or text on the bag surface, which telegraphs through onto the print — logos on one side, the purge valve on the other. The bag shown here fits an 11″×14″ (28×35.5 cm) print.

A Second Use: The Easel

A quick experiment worth sharing: I found that a standard vacuum bag can do double duty with a large photo printing easel. The easel already holds the negative down well on its own, but running the bag under vacuum gives real peace of mind — nothing shifts during exposure, even on longer runs. Just size the bag a little larger than the easel frame itself, enough to give yourself some margin. It’s a small trick, but it’s saved me from a few ruined exposures.

This adjustable easel lets you set precise, repeatable borders on your prints — no masking tape, no cutting the paper, and no marking up your negatives.

You can also tape your negative directly to the easel and use it as a registration frame — handy for repeat exposures or multi-layer printing where alignment matters.

The Results

Super sharpness and clear contact quality compared to the plain vacuum-bag method, using any exposure times for Sun Prints or UV LED exposure units.

This low-cost method is used repeatedly in my workshop and teaching settings rather than a single studio session, and it holds up just as well as my $300 split-back frames.

Constantinos Loumakis, Commercial Advertising Photographer, alternative process printmaker, inventor of the Algorithmic Pigment Process (APP). This vacuum bag system is also part of Constantinos’ workshops.