Have you ever pulled out a crumpled grandfather's birth certificate, a long-ago stained and creased map, or a precious certificate resembling a concertina from a drawer? The first instinct usually suggests two solutions: putting the document under a pile of the heaviest encyclopaedias or... reaching for the household iron. From a conservation perspective, both these ideas can lead to irreversible disaster.

Old paper is extremely delicate, and the cellulose fibres trapped within it lose their elasticity over time. In this guide, you will learn, How to safely straighten creased pages, based on proven, non-invasive methods. We will explain why temperature is your greatest enemy and show you how to perform a professional paper „relaxation” treatment step-by-step in your own home.

Why is a domestic iron paper's worst enemy?

This is one of the most harmful and frequently repeated myths: „if I iron a cotton shirt, I'll iron paper too, since it's also a fibre.” Unfortunately, physics says otherwise. The short cellulose fibres, upon contact with the fierce, dry heat from an iron (even on the lowest silk setting, which reaches 90–120°C), literally „cook”. The water naturally bound within the paper evaporates instantly, making the sheet brittle and yellow.

But it's not the burning of the paper itself that's the biggest risk. The real tragedy befalls what is printed on it:

• Melting toner Most modern documents are printed using laser printers. The resins and polymers contained in the toner begin to melt and liquefy at temperatures of 110–130°C. If you apply a hot iron to them, the print will literally peel off the paper and stick to the appliance, destroying the text irreversibly.
• Black receipts Great care must be taken with faxes, receipts, and printouts from thermal terminals. They contain special dyes that are activated by heat. Even brief contact with temperatures of just 60°C (e.g. in a heated car glove compartment or under a warm iron) is enough to turn the entire sheet into a useless, black rectangle.

Office tape infestation

When creased, dry paper is forcibly straightened, it often cracks along the folds. What do we do then? We reach for the most ordinary, office tape. This is another mistake that all state archives strongly warn against.

The adhesive from standard tape degrades instantly and penetrates deeply into the fibres, creating unsightly, rust-yellow stains. For a professional conservator, removing just 2.5 centimetres of such tape is often as much as Three hours of arduous work using strong solvents under a microscope! If your document is torn, instead of office solutions, use professional conservation tape, such as acid-free Filmoplast, which is safe for artefacts and does not yellow over time.

Fibre relaxation, the conservators' secret

Since you can't iron it hot or bend it dry, how do you straighten paper? The key to success is moisture relaxation. Before you apply any pressure, you need to gently loosen and make more flexible the petrified, dry cellulose fibres.

How to build a homemade humidification chamber? (Step by step)

You don't need a sophisticated laboratory. Simple elements are sufficient to create a safe and humid environment for your keepsake:

1. Prepare the container: Find a sealable plastic container (e.g. a flat under-bed storage box), noticeably larger than your document.
2. Moisture layer Place a clean, cotton cloth, generously dampened with distilled water (ordinary tap water contains minerals that can damage the paper), at the bottom, and then wring it out very thoroughly.
3. Insulation Place an insulating grid (e.g., a plastic sink grid or a hard mesh) on a cloth to create a gap.
4. Protective barrier On the grate, place polyester film or a smooth plastic sheet. Please remember: the document must not come into physical contact with a wet cloth or water droplets under any circumstances! It only absorbs airborne vapour.
5. Relaxation Place your crumpled, dry document on the protective barrier and seal the container securely.

Duration: Leave the document for 2 to 4 hours, checking on it every half hour or so. When the process is complete, the paper will be slightly cool to the touch, flexible and will yield under the weight of your fingers without „crunching.”.

Cold pressing – fixing the flat shape

Once you have retrieved your relaxed, slightly damp, and soft document from the chamber, you must dry it under even pressure. Conservators call this Cold Pressing, which is cold pressing.

1. On a flat, hard surface, lay a clean sheet of smooth blotting paper or special moisture-absorbing paper. For such tasks, it is ideal acid-free paper.
2. Gently lay your relaxed document on it, smoothing out any creased corners with your fingers.
3. Cover the document with a second layer of acid-free paper or tissue paper (we call this a „sandwich”).
4. Place a rigid, smooth board on top – this could be a piece of thick organic glass, Plexiglas, or a clean, smooth plank. It's important that it's larger than the document itself.
5. On the board, distribute the weight evenly – this could be heavy dictionaries, weights, or blocks made of laboratory equipment introductory.

Leave the entire thing completely undisturbed for 12 to 24 hours. If after this time the paper is still slightly cool (which means it still contains moisture), replace the outer blotting papers with dry ones and leave the document under weight for another day.

Summary and safe storage

Straightening old, valuable documents is a process that requires patience, not high temperatures and brute force methods. Replacing a domestic iron and office tape with a safe humidity chamber and cold pressing is a guarantee that you won't damage your family heirloom.

Once your letter, deed, or diploma has regained its perfectly flat shape, ensure it never gets creased again. It is best to protect straightened collections by transferring them to special, rigid folders and boxes. Certified, acid-free products designed for storage and archiving you will find in the CartaPro offer, which will allow you to enjoy your saved treasures for many decades in perfect condition.