CORE-BOND B73 – TDS 1/2
CORE-BOND B73
Sprayable/Pumpable Polyester-based Core
Adhesive for Foams and Balsa
Introduction
Core-Bond B73 is a polyester-based core bedding compound, developed for both hand-layup and vacuum-bag core
installation, and is used as a 2-part system in conjunction with a priming resin applied to the core surface. Lightweight
and non-sagging, Core-Bond is catalyzed with a BPO catalyst and is formulated to the degree of elasticity required for
the core to skin interface. With a shrinkage of less than 1%, Core-Bond significantly reduces the possibility of print-
through. Core-Bond B73 can be sprayed or pumped, can be spread out for a uniform thickness with a (6mm) V-notch
stainless steel trowel and achieves a thin bondline of approximately 1/32 -3/64 (approx. 1mm). One gallon (3.78 liters)
covers approx. or 30 square feet (3m2 ). Always prime core surface with a catalyzed resin. The Core-Bond combines
with the priming resin for a thorough cure and good cohesion. The priming resin should appear between the blocks
of contoured cores, or in the bleeder holes of plain core sheets for a visual inspection of a good bond. Core-Bond B70 is
used for hand application, B71/75 are sprayable versions using MEKP. (Page 2)
General Properties
Color White
Density 0.75 -0.82 g/cc (6.25-6.83 lbs./gallon)
Compression strength 1800 psi
Deformation before rupture 9.8%
Shrinkage Less than 1%
Thixotropy Non Sagging
Capillary absorption None, non-porous surface
Water absorption Less than 1%
Viscosity 112,000 – 128,000 cps
Installing a core material with Core-Bond B73 is a 2-part system consisting of Core-Bond, which is catalyzed with a
BPO/4 (40% benzoyl peroxide, such as Benox L-40LV (www.norac.com) or equal, white paste catalyst, and a GP (ortho)
laminating resin for priming the foam core, which is catalyzed with an MEKP DDM-9 (or equal) catalyst. A green pigment
can be added to the white BPO catalyst for easier identification that the catayst is well dispersed (Please contact us).
The catalyzation instructions below for a 50-55 minute are based on a 100 gram mass. For an under the core gel time,
add approx 5-10 minutes. The Core-Bond and priming resin should gel at about the same time. Verify this under shop
conditions using the Core-Block Test (refer to ATC Core-Bond Manual).
Core-Bond B73 Catalyzation Chart
(incl. Magnum Venus Slave Arm Settings, BPO 40% Catalyst, for 50-55 Minute gel time in a 100 gram mass*
Core-Bond B73 R
(Regular Version)
Core-Bond B73 S
(Summer Version)
Core-Bond B73 W
(Winter Version)
Temperature
F C
%
BPO
(weig
ht)
cc/Gl
n.
(3.78
l)
gr/Gln.
(3.78 l)
MVP
Slave
Arm
Stg.
%
BPO
(weig
ht)
cc/Gl
n.
(3.78
l)
gr/G
ln.
(3.7
8 l)
MVP
Slav
e
Arm
Stg.
%
BPO
(weigh
t)
cc/Gl
n.
(3.78
l)
gr/Gln
.
(3.78
l)
MVP
Slave
Arm
Stg.
55 13 3.90 85 102 2 1/4
60 16 3.10 69 83 1 3/4
65 18 3.90 85 102 2 1/4 2.70 59 71 1 1/2
70 21 3.25 71 85 1 3/4 2.25 49 59 1 1/4
75 24 2.70 59 71 1 1/2 3.90 85 102 2 1/4 2.00 43 43 1
80 27 2.20 48 58 1 1/4 3.10 69 83 1 3/4
85 29 1.90 41 49 1 2.70 59 71 1 1/2
90 32 2.25 49 59 1 1/4
95 35 2.00 43 52 1
* Allow an additional gel time of approx 5 – 10 minutes in the core installation (Core-Block-Test). Please adjust gel times
for Core-Bond and the priming resin to shop conditions using this chart as a guideline. Chart based on B73 (0.78 g/cc)
and BPO 40% (1.35 g/cc)
CORE-BOND B73 – TDS 2/2
Dispension Equipment
Core-Bond B73 is supplied in drums. Internal mix dispension equipment is manufactured by: Magnum Venus Products,
www.mvpind.com; GS Manufacturing, www.gsmfg.com; Glas-Craft, www.glascraft.com.
Priming the Core
Priming the core is a necessary step which achieves the required bond strength.The resins used are normally low
styrene content (below 40%) medium reactivity GP/ortho resins, ortho/DCPD blends, vinylester resins, and
vinylester/DCPD blends. Iso resins may not work as well, especially in higher temperatures, as they can force styrene
into foams or balsa causing bondline undercure. To check the priming resin suitability, make a Core-Block Test as
described in the ATC Core-Bond Manual . SB-ATC also supplies a designated priming resin, ATC Priming Resin (which
can also be used as a core surface sealing – or hot coating resin). This resin is recommended especially when hot and
humid shop condition exist. The priming resin needs to be catalyzed for a 15 minute gel time in a 100 gram cup for the
temperatures listed in the Core-Bond catalyst chart. Follow the MEKP catalyst levels recommended by the priming resin
manufacturer. The objective is for the priming resin to catalyze in a thin film on the core material surface at about the
same time as the Core-Bond. Please refer to the
Spread Core-Bond with a notched Trowel
Core-Bond should be spread with a notched trowel, the ideal configuration has 1/4 (6mm) equilateral triangles. For
contour-cut foams or balsa, as additional material may be needed to fill the kerfs that open up in a curved section. The
trowels are available through your
Core Installation
Refer to the ATC Core-Bond Manual for proper installation procedure and contact an SB-ATC representative for
vacuum-bagging recommendations specific to the core being used. For temperatures outside the listed range, consult
SB-ATC. It is not normally necessary to agitate the material in the dums before use. However, it is recommended to
occasionally stir the BPO catalyst before use.
Storage
For maximum shelf life, store Core-Bond and BPO catalyst in a cool, dry area, maintaining the temperature between 10 –
20 C (50-70 F). This would also extend the gel time in warm climates as the material starts out cool when used. Avoid
storing in heat or direct sunlight.
Shelf-Life
Core-Bond B73, following recommended storage conditions, has a 12 months shelf life. We recommend gel time tests at
all times, but after 12 months a gel time test will indicate the useability of the material.
Core-Bond B71/75 sprayable Versions with MEKP Catalysts
There are two sprayable versions of Core-Bond for use with a MEKP catalayst, Core-Bond B71 (18-24 minute gel time)
and Core-Bond B75 (35-45 minute gel time). Please refer to Core-Bond B71/75 Technical Data Sheet.
Green Catalyst Pigment
A green catalyst dye can be supplied through your SB-ATC distributor. It comes in a 85 gram/container, which is
sufficient to pigment 19 liters (5 gallons) of the white BPO paste catalyst.
NOTICE: All precautionary labels and notices should be read and understood by all supervisory personnel and
employees. Consult OSHA and government regulations for additional safety and health information. Purchaser is
responsible for complying with all federal, state, or local laws and regulations covering the use of this product. The
information contained herein is correct to the best of our knowledge. Please check our website for latest updates. The
recommendations or suggestions contained in this bulletin are made without guarantee or representation as to results.
We suggest that these recommendations and suggestions are evaluated by the purchaser s technical staff prior to use.
Our responsibility for claims arising from breach of warranty, negligence, or otherwise is limited to the purchase price of
the material. All values can be revised due to ongoing testing and are subject to change without notice.
Version 1 : February 2016
All information on this data sheet is based on laboratory testing and is not intended for design purposes. Scott Bader makes no representations or warranties of any
kind concerning this data. Due to variance of storage, handling and application of these materials, Scott Bader cannot accept liability for results obtained. The
manufacture of materials is the subject of granted patents and patent applications; freedom to operate patented processes is not implied by this publication.
SCOTT BADER COMPANY LIMITED
Wollaston, Wellingborough, Northamptonshire, NN29 7RL
Telephone: +44 (0) 1933 663100
Facsimile: +44 (0) 1933 666623
www.scottbader.com
Plant: SCOTT BADER – ATC
2400 Canadian Street, # 303
Drummondville, Quebec J2C 7W3
Tel: 819-477-1752
SCOTT BADER COMPANY INC.
4280 Hudson Drive, Stow, OH 44224, 1-800-839-4765
Telephone: +1 330 920 4410
www.scottbader.com