Series editors' preface - Wood Tools

186 Conservation of Furniture
which have been used in conservation include
the Araldite range from Ciba Geigy, the
Ablebond range from Ablestick, the Rutapox
range from Bakelite, and Hxtal-Nyl-1 from
Conservation Materials.
Cyanoacrylates adhesives are popularly
called ‘SuperGlue’ after an early trade name
(Figure 4.15m). The first of these adhesives
(Eastman 910) was introduced in 1958 and the
number of available brands and range of physical
properties have increased markedly since
then. Unlike the previously described thermosetting
resins, no separate hardener is
required for curing. The clear fluid adhesive
polymerizes very rapidly in contact with a
weak base, such as the water that is present in
or on virtually all substrates. The chief advantage
of cyanoacrylates is their very rapid cure
which eliminates the need for any clamping
other than hand pressure. They will stick to a
wide variety of substrates (including skin!) and
so are useful in bonding dissimilar materials.
Open time is measured in seconds but is
shorter on alkaline substrates and longer on
acidic substrates such as wood. Cyanoacrylates
(i)
O
H2C CH CH2 Epoxy
group
(ii)
H H
(iii)
N
R
N
H H
O
OH
CH
CH
OH
CH 3
C
CH 3
CH 2
CH 2
N
R
N
O
CH 2
CH 2
CH 2
OH
CH
CH
OH
initially had virtually no gap-filling abilities and
would not cure in any but very thin glue lines.
New varieties are available which have good
gap-filling characteristics. They are hard and
machinable with low creep. Cyanoacrylates
have short shelf lives and show poor long term
chemical stability when cured. Adhesive joins
become weaker and prone to failure as they
age. They can be extremely useful in quick
assembly and can function as clamps in difficult
circumstances but should be considered
temporary in conservation terms unless backed
up by another adhesive or fastener system. The
cured material is swollen, but not dissolved, by
acetone which can be used to effect its
removal from non-porous substrates.
Thermosets used in moulding and casting
are discussed in Chapter 10.
4.8 Examination and identification
of adhesives, coatings and media
The difficulties inherent in the identification of
surface finishes are reviewed by Mussey
O
CH CH2 Epoxy
group
CH2 C
C N
H2O [ CH2 C
C
] n
N
CH2 C
C N
CH2 C
C N
C O
C O C O C O
O
O
O
O
CH3 CH3 CH3 CH3 Methyl
cyanoacrylate
monomer
+ Water Polycyanoacrylate
Figure 4.15(l) (i) A small molecule with
epoxy groups at each end (resin); (ii) a
diamine (hardener); (iii) a crosslinked
epoxy network
Figure 4.15(m) Methyl
cyanoacrylate monomer +
water → polycyanoacrylate
(Super glue)