85-03-01194
FV48
Page
31
The polyester resin used on marble slabs c an discolor when exposed to temperatures greater than 150
o
F
and will structurally fail at temperatures above 230
o
F. The epoxy resin coating used on granite slabs are
resistant to discoloring and structural failures up to 350
o
F. Mendota does not assume any liability for
discoloring, flaking or cracking of marble or granite.
Temperatures on facings around Mendota fireplaces can reach 350
o
F directly
outside the top convection air gap. These temperatures will discolor
polyester resin coated marble facings and can cause the polyester resin
coating to fail near the top convection air gap.
Mendota cannot guarantee suitability of use of any marble slabs
or tiles that have a polyester resin coating applied to it and
cannot guarantee against discoloration or structural failure of
marble or polished stone facings that have a polyester resin
coating. Consult with your local stone supplier.
Prior to use of any marble, granite or polished stone facing material,
especially white colored ones, run heat exposure tests on a sample piece.
Expose sample pieces to temperatures between 275
o
F and 350
o
F for a period
of eight hours. Compare the heat exposed sample to a control unheated
piece and judge for color changes. Do not use if any color changes are evident.
Mendota recommends the use of honed bare marble and bare stone facing materials or honed bare granite
and epoxy resin coated granite only.
Mendota cautions that due to natural structural defects that can exist within marble and stone pieces, cracking and/or flaking
of the marble or stone is possible and must be considered prior to selection and application around Mendota fireplaces.
Mendota further cautions that proper adhesives be used to attach stone facings. Pay attention to the potential of off gassing of
chemical vapors from mastic and other adhesives. Improper selection can lead to emission of chemicals with unwanted smells.
Suitable Paints and Sealant Materials
3.2.13.5.1
Paint Types Approved for Use
Industrial Acrylic Paints, Alkyd based Paints. When selecting paint for applications on facings, mantels, corbels or floors within
2’ in front of a fireplace raised 6” or higher, avoid off the shelf paints which may have modifier additives u
sed to increase
“hiding” ability, accelerate drying times and curing times. Consult with a reputable paints and sealants supplier and acquire
industrial acrylic paints or alkyd-based paints.
3.2.13.5.2
Sealants Type Approved for Use
Heat resistant polyurethane sealants which are not damaged by prolonged exposure to raised temperatures. Many are flame
resistant, meaning that they resist ignition when exposed to high temperatures and can insulate the substrate and delay
damage to it. When selecting polyurethane for appl
ications on facings, mantels, corbels or floors within 3’ in front of or above a
fireplace, avoid off the shelf urethane sealants which may have modifier additives used to accelerate drying times and curing
times. Consult with a reputable paints and sealants supplier and acquire heat resistant polyurethane sealants.
3.2.13.5.3
Wood Application Cautions
If wood used around or in front of the fireplace has been chemically cleaned or bleached prior to staining or painting, it is of the
utmost importance to make certain that the cleaner or bleach does not remain in the wood substrate under the final paint or
sealant applied. If any cleaner or bleach remain within the wood structure, application of heat from the fireplace, even low-level
heat, will cause the cleaner or bleach compounds to expand or evaporate causing separation of the paint or sealant from the
wood surface and may cause peeling or bubbling of the paint or sealant.
Moisture content of the wood substrate is also of critical importance. High moisture content wood when heated will yield
evaporation of the moisture and hydraulic pressure under the paint or sealants which can lead to peeling or bubbling. Always
select the lowest moisture content wood substrate.
Figure 3-23 Top Air Gap
TOP AIR
GAP
