N O T E ' N UM B E R
T E C H N I C A L
UNITED
STATES
DEPARTMENT
FOREST
OF
FOREST
AGRICULTURE
PRODUCTS
SERVICE
LABORATORY
REvlsED
MADrsoN 6. wtscoNslN
COMMERCIAL
F-2
LIQUID
December L952
GLTIES
Although a number of different typea of woodworking glues are now suPplied in liquid forin, the term "liquid gluerris generally limited to cerare supplied in liquid
lain glue" Lf arri*al or sometimes plani originthat
In the past, such tiquid gluee"were usually manuform ready to use.
More
factured from the skins, heads, and swimming bladdere.of fish.
recently, other liquidglues have been developed,'based on animal glues
Liquid glues are'also
derived frorn hides, skins, and bones of cattle.
prepared from etarch, natural gurns, casein, and certain thermoplastic
synthetic resins.
At the Foreet Products Laboratory tests have been made on a number of
An earlier serieg of teets indicaied that
gluea of animal or fish origin.
different glues variedwidely intheir resultant joint strength' Sorre were
eo weak as to be entirely unsuitable for woodworking purposes, and other s
cotnpared favorably in strengthwith conventional animal glue (tthottr glue
More recent tests on samples of liquid animal gluee
or rlhide'r glue).
although eotne glues gave moie
indicated rnore consistentperformance,
good reeults than others when bonding wae conducted under a
uniformly
The better
and asser-nbly conditionE.
series of different temperature
glues were again cornparablewith-rthotrr glue. Insubsequent tests, however, after 6 monthsr storage at 80" F", these same liquid glues Produced joint strengtJr values of only 45 to 65 percent .of their strength
No significant physical changes in the glue sarnples
when used fresh.
These results indicate that
were observed during this storage period.
samplesof liquidglues ehould be usedas soon aspossible.after receipt.
Liquid glues may be tested by gluing tJgether pairs of carefully selected
hard maple blocke and testing the joints irt a testing machine to deter(See American Society
rnine the force required to shear them apart.
for Testing Materials Method D905-49. ) Irr suchtests at the Laboratory,
average shearing etrengthfrom
the better liquid glues showedvaluesfor
1,600 to 3, 800 pounds per square inch of glue joint, depending on the
gluing conditiong used.
high adhesive etrengtJr a^ad convenience of use
In addition to uniformly
are ddEired ia a ligaid glue.
as received,
certain other characteristics
trn its
When spread upon wood eurfacee, it should rtsetrt or dry rapidly.
tenperaat all ordinary
container it should remain fluid and workable
of high temtures.
It should not be unusually susceptible to thi.action
eenei'
Liquidglueeless
peraturee, high humidity, molds, and bacteria.
effecte during gluing than typical rlhotrr gluea wopld
tive to temperature
of these glues 4ae not yet been adebe $.eeirable,
but such versatility
quately eatabli+hed. .
tests gave evidence that tb.e etrengtJr of a liquid glue,
The Laboratory
like that of trhotn g1ue, depends largely uPon ite trbodyrr or thicknesE' or
Generally the thickest or most
etrictly epeaking, upon its viscooity.
vidcous gluee showed the greateet adhesive btrength.
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