Working with historical processes gives us the freedom to choose the support we wish to print on. For gum printing a wide variety of papers can be experimented with, which include; watercolour, etching and some handmade papers. Ultimately paper choice will be determined by the results you are seeking. A paper that might work for a single coating of gum may not be tough enough for the repeated handling necessary with printing multiple coats.

Choosing paper

My personal preference is to work with watercolour papers, which offer archival permanence, and provide the strength to deal with repeated physical handling, necessary for multiple gum printing. In choosing papers you want to consider the following;

• Ideally choose a paper weight of no less than 300gsm (anything under this just won’t be strong enough to deal with the constant physical handling). These days I work with papers in the 600-640 gsm range.
• Be aware that the surface texture of paper, after soaking and drying will usually be coarser than what you view before the first immersion in water. So choose a texture that is a little finer than what you desire in your final print.
• Coarser textured paper will handle greater physical manipulation than a smoother texture, however the smoother papers will print more detail.
• A good test for choosing papers for multiple gum printing is to immerse the paper in water - if it buckles and becomes very soft it probably won't work well. Also check how it dries - ideally you want the paper to dry reasonably flat, with minimal curling.

Over the years I have used a range of different papers. My initial experiments were single coatings of gum on Rives BFK, un-sized. Later as I experimented with multiple coatings I switched to Strathmore watercolour paper. My first experiments with this paper were un-sized.

The list below is a selection of papers I have used at one time or another. Please note that manufacturers often change their process, so characteristics change over time.

• Fabriano Artisco - Hot Pressed and NOT - a solid paper with excellent wet strength and minimum curl on drying. It provides good dimensional stability and will handle a significant level of physical manipulation. Consistency from batch to batch is also good. The NOT surface has a noticeable texture which will not suit all tastes; the HP surface offers a good smooth texture that will hold detail well.
• Strathmore watercolour - I used this paper for years — initially without sizing, though later manufacturing changes required the application of sizing. I have been unable to source this paper now for many years.
• Bockingford - a good tough paper that works well for multiple gum printing — its texture does not suit all tastes.
• Saunders Waterford - Hot Pressed and NOT - I have successfully used this paper for some years but have found recent batches inconsistent.
• Arches - Another paper I have used successfully in the past but recent tests have shown significant buckling and distortion when immersed in water.

Pre-shrinking
If you plan to make multiple exposures pre-shrinking is recommended. After paper has been soaked and dried for the first time its dimensions change — making it diffcult to accurately re-register the negative after the first printing.

 

So the first step is to pre-shrink the paper in hot water for up to 30 mins. Hang up to dry (do not use artificial heat to speed drying), and repeat the process.

 

Sizing
Sizing helps ensure that you can successfully apply multiple coats of gum emulsion to the paper without problems of pigment staining (though the proportion of pigment/gum will also affect this). Pigment stain degrades the highlights and muddies additional applications of colour - so you definitely want to avoid it!

 

Sizing involves the application of a layer of hardened gelatine size to your preferred paper. This can either be applied by immersing the paper in a bath of size, or by applying by brush.

 

The sizing procedure is as follows;

• Make a 3% solution of gelatine by dissolving the required amount of gelatine in cold water (quantities will depend on whether you intend to immerse the paper in a sizing bath, or apply the gelatine by brushing), e.g. 29 grams gelatine per litre of water.
• stand for 10 minutes to allow the gelatine to dissolve and swell
• raise temperature to approximately 43°
• add formalin to the gelatine solution to harden it (Warning - formalin is a toxic and volatile chemical. Work in a well-ventilated area). The amount of formalin to add will depend on the volume of your sizing solution, but should be 2% per volume, i.e. 25ml formalin per litre of size.

Tray sizing
pour the gelatine size into a tray and immerse paper for 1-2 minutes
Draw the paper over the edge of the tray to dislodge any air bubbles on the surface of the paper (check for these on both sides — re-immerse paper if necessary), and hang up to dry.

 

Brush sizing
Mark out the negative area on the paper and use painters tape to protect the non-printing area. Once coated leave the tape in place for about 10 mins before removing. Hang up to dry — do not use heat to speed up the drying, this can cause the paper to dry unevenly which will cause problems with re-registering later.