Technical Specifications

These joint
guidelines are to
ensure suff i c i e n t
Log Jam mass to
absorb log move-
ment and main-
tain a tight seal for an extended period of time.
Regardless of the width, the depth should not be
greater than 1/2”.
Backing Material: A backing material should be
installed between logs prior to chinking. An open-
cell type is recommended to speed drying. A closed-
cell type is more moisture resistant. Choose based on
your needs.
If round backing material is used, care must be
taken to apply sufficient material over the apex of
the rod so that the chinking is not too thin, making it
susceptible to tearing.
Restoration
All logs should be free of dust, grease, uncured
oils, and other contaminants. Remove all loose mortar.
Bond-Breaker: When
using Log Jam as a restora-
tion chinking over old mortar,
a “bond-breaker” tape should
be applied over the center of
the existing mortar. A variety
of plastic tapes may be used,
such as clear mylar packaging tape or duct tape.
Applied to old mortar prior to rechinking, the
bond-breaker provides a surface Log Jam will not
stick to. When movement occurs, Log Jam will be
free to stretch.
Tooling: Log Jam should be tooled to contact at
least 1/2” of the bare wood surface on either side of
the old mortar. This will ensure adequate adhesion.
Round Logs
Be sure Log Jam has been tooled tight
to the log surface. Log Jam should contact
between 1/4” and 1/2” of the log surface.
Square Logs
Be sure the spline is dry and clean
before applying Log Jam. Apply
tape on the center of the spline
as a bond-breaker, whether it is
rigid material such as masonite
or wood, or non-rigid material
such as styrofoam or bead board.
Because the joints are often very
wide (up to 4”) multiple passes are often required.
Log Jam should be applied to the upper and lower
edges of the joint first, and if a gap exists between
the two beads, fill the gap with additional chinking.
It is very important to tool the bead, especially along
the upper and lower edges so that Log Jam is forced
into good contact with the logs for proper adhesion.
Applying Log Jam
Surface Preparation
Surfaces: Surfaces should be clean, structurally sound, free of
uncured oils, dirt and other loose materials. Log Jam may be applied
to slightly damp logs if no additional water is actively rewetting the
surface. Sunlight, according to the USDA Forest Products Labs, can
create unsound wood in as little as 1-2 weeks—so chink shortly after
good prep work is done.
Wood Treatment: A good wood coating such as Capture or High
Sierra is highly recommended for exterior surfaces, and most should
be applied before chinking. Wood sealers, preservatives, or stains
should be thoroughly cured before applying Log Jam.
A few sealers (especially those heavy in wax content) may interfere
with adhesion. Call Sashco for compatibility information.
If stain is applied over cured Log Jam, the chinking will be tinted to
the stain color but will be affected differently from the surrounding
wood.
Surface Temperature: Surfaces should be between 40˚ and 90˚F
when applying Log Jam.
When using 5-gallon pails, Sashco’s patented Snorkler™ Pumping
System, grout bags, or bulk loading guns may be used. Because Log
Jam contains no heavy abrasives, downtime and replacement of costly
bulk equipment can be reduced.
Tooling
Log Jam may be tooled with ordinary mason-
ry-type tooling blades of 3/4” to 1-1/2” in width.
Using a spray bottle, lightly mist Log Jam with
water to allow the trowel to glide over the sur-
face when tooling. A damp polyethylene foam brush or rubber spatula
also works. Log Jam should be tooled tightly to contact at least 1/2” of
the log surface.
A mixture of 1 part denatured alcohol to 2 parts water can be used
for misting the chinking (immediately prior to tooling) when the tem-
perature is over 70˚F. If you are working in the sun and the chinking is
skinning over too quickly, straight alcohol can be used. When the tem-
perature is lower than 70˚F the alcohol is not necessary.
Cold Weather Application
The logs must be free of frost, and the surface temperature of the
logs should be at least 40˚F (and rising).
Tent out the walls with clear plastic and keep them warm with
propane heaters. Once the surface temperature is at 40˚ F, apply the
chinking. The chinking will flow better if the pails are at room tempera-
ture and kept warm. Make sure there is air circulation so moisture does-
n ’t form on the logs (from the humidity created by the propane heaters)
causing water damage. Some venting of the tent up high will help with
this problem. Leave the tent intact, with warm air, for 2-4 days so that
the chinking can start to properly skin over. Due to the cold temperature
it will take much longer than normal for the Log Jam to fully cure, but it
will eventually dry to a rubbery seal if left undisturbed.
"Chinking and green logs"
Be aware that there is always a high risk of the chinking cracking
with "green" log construction, especially on interior applications – due
to the extreme movement of the logs as they typically shrink. There
are economic trade-offs when using green logs, and one of those trade
offs is the cost of repairing chinking when it prematurely fails due to