Acid
Acid attacks cellulose fibres by shortening them, causing paper to discolour, become brittle and eventually
turn to dust. Exposure to light and damp accelerate this process. Acid is generated by the lignin (tree sap) in paper. It
can also be introduced by chemicals used in paper manufacture, framing materials and atmospheric pollution.
Acid Burn
Disscolouration caused by acid migrating onto the artwork, often from the cut edge of the windowmount.
Acid Free
Containing no acid. Often used to describe board, paper or adhesive that has been
treated to give a ph value of more than 7.
Acidity and Alkalinity
Acidity and Alkalinity are measured on a pH scale ranging from 1 to 14. The neutral
point is 7.00 and at this point the substance or material is neither acidic or alkaline. The higher the number, the higher the alkalinity.
The difference between numerals is significant because the scale is logarithmic which means each pH change of one indicates a
change of 10 times the acidity or alkaline measurement. As a frame of reference, at pH 10 is soap; pH 3 is vinager.
Conservation materials should be at pH 6.5-8.5.
Paper can be naturally neutral or chemically neutralized. Although a paper
may be acid-free or have a pH of between six and eight, it may become increasingly acidic over time.(extract from Conservation framing by
Vivian Kistler)
Alkaline
The opposite to acidic. Alkaline materials are used inconservation framing and have a ph greater than 7.
Calcium carbonate is commonly added to paper as an alkaline reserve, to counteract the paper's natural degradation. Alkaline
reserves added to paper are often called buffers.
Artists Prints
Includes techniques such as etching, lithography, woodblock printing and silkscreening, created
by and printed by the artist. BSI (British Standards Institution ) defines this type of print as a category 'A' where the artist
creates the original work and makes impressions from the plate. If other people are involved in the printmaking process and not
the artist, this defined by BSI as a category 'C' type print.
Conservation Board
We use a solid white conservation board from Arqadia. Made from
a high quality bleached alpha cellulose, the board is essentially lignin-free (see Acid entry ). Under accelerated ageing conditions
the board changes from pH 9.4 unaged, to pH 7.5 over a 100 years; pH 7.5 in 150 years; pH 7.5 in 200 years.
Conservation tape
We have been using Filmoplast P90 tape for about twenty years now to seal the
glass/mount/foamboard package to keep out dust and insects. The tape is acid free, water based, and non-ageing.
Cibachrome Prints
Cibachromes are ultra high gloss photographs that are very sensitive
to marking, and therefore demand the upmost care when handling. Cibachromes are produced by Iford, and are now branded as
Ilfochromes. These photographs should not be drymounted, but hinged, for small prints, and placed onto acrylic sheet held by static
force, for larger prints.
Drymounting
Drymounting is a method of sticking paper and light fabrics to a board
without the application of wet glue. The drymounting tissue softens under heat and pressure in a vacuum press. We find this method
very good for items of relative low value, such as posters and prints. Objects of value should never be glued to a board!
Giclées Prints (pronounced zhee-clay)
Digital prints from a image file that are produced from an printer using
light resistant pigment inks that have greater luminosity than conventional lithographic prints.
Etchings and Engravings
A print made from an inscribed or etched plate. The copper plate
is covered in wax into which the image is drawn. The plate is immesed into an acid bath which eats into the exposed parts
of the plate. When the wax is removed the drawn image is etched into the plate allowing ink to fill into the design. The plate is put
on an etching press and a roller then passes over the plate under pressure, picks up the ink image and rolls this onto a damp paper.
Each colour is a separate proceess, and each print must be exactly aligned.
Low Reflection Glass
Approximately only 92% of light is transmitted through glass, the rest
is reflected towards the viewer. Low reflection glass transmitts over 99% of light, giving a brighter, clearer image, with minimal
reflection. Most types of Low-Reflection glass are coated with a multi-layer optical interference coating (OIC) which is very
similar to the lens on cameras and binocolars. Coated glass must be handled and cleaned with care, as the coating can be vulnerable
to scratching.
Light Damage
Light damage to artwork is the most pervasive and most difficult to avoid. Light will cause
the paper and the artist's medium to change by fading, changing colour, altering chemicals in paper and paint, and degrading cellulose.
The extent of the damage depends on the intensity of the light and length of exposure.
Artists' Proofs
Artist Proofs are prints that tradionally have been used to check colour, and alignment, prior to the print run.
Today artists' proofs are mostly a marketing tool and have no real intrinsic value. These prints are identified by the letters 'AP'
usually in pencil on the bottom left margin of a limited edition.
UV Glass
We use Tru Vue Conservation Clear 2.5mm Glass which has a filter on the side facing the Artwork. This
absorbs 98% of the damaging UV energy that exists just beyond the violet end of the visable spectrum. It is important to realize
that UV Glass does not offer complete protection, and Artwork should still be shielded from direct and excessive sunlight.
UV is defined as energy within the 300-400 nanometer range. Ultraviolet (UV) light transmits energy into the atoms of the object
it strikes. This energy excites the atoms and transforms them into new substances, which manifests in artwork as fading and degradation
of paper and fabrics.
Float Glass
We use a quality 2mm Float Glass for the most of our framing tasks. This glass has very few flaws,
and good optical properties, although it has a very slight greenish cast due to the iron content in its composition.
Large works require 3mm Float Glass which is considerably heavier than the 2mm.
Silkscreen Prints
Silkscreen printing is a method of pushing ink or paint through a fine
mesh that holds the stencil through which the paint passes onto the paper. Sometimes called Serigraphs, these prints are often
printed in bold flat colours on heavy weight paper, normally in small editions.