.. CLICK HERE TO GOOGLE SEARCH OUR ENTIRE WEB SITE FOR KEY TERMS/WORDS ..
CONTACT INFO
- ORDERING - HOW TO REACH US - PHONE/EMAIL/FAX INFO
Return to Progressive's boating site
Return to Progressive's commercial site
Your Host and Tour Guide:
Paul Oman, MS, MBA - Progressive Epoxy Polymers, Inc.
Member: NACE (National Assoc. of Corrosion Engineers), SSPC (Soc. of Protective Coatings)
"Professionals helping Professionals"
In the spring/summer of 2001 I searched the Internet looking for information about coal tar epoxies. I found lots
of product pages, but nothing about why and where coal tar epoxies should/could be used in place of regular epoxies.
What are the Pro's and the Con's of coal tar epoxies? I have now learned these things and wish to share the information.
Please note that our company, Progressive Epoxy Polymers, Inc., recently added a coal tar to the line of epoxies
and clear coat products that we sell. It is a solvent-free coal tar epoxy of very good quality (using the most
modern epoxy components to a 38% coal tar base). It sells in 2 gallon kits. More information and links to our company
web site are at the end of this document. So much for the advertisement/disclaimer, now the information promised
above!
Background History
Coal tar epoxies are essentially a mix of coal tar and epoxy resins (and not all epoxy resins are the same). Coal
tar epoxies were at their peak of popularity in the 1960's (???) through about 1990. After that, non-coal tar epoxies
replaced coal tar epoxies due largely to health concerns over long term exposure and direct contact (by coating
applicators) to the ‘tar'.
Advantages of Coal Tar Epoxies
Coal Tar epoxies are inexpensive compared to most non-coal tar epoxies. The offer considerably more flex
(or elongation) then regular epoxies. This makes them useful on garage floors where turning/spinning tires will
‘stretch' the epoxy, as well is in situations with a lot of expansion and contraction. Coal Tar epoxies are also
famous for protection from moisture, both in the water (such as barge hulls) and when buried underground (such
as pipelines and underground tanks). A key advantage of coal tar epoxies is its ability to bond to oily surfaces
(thanks to the hydrocarbon nature of the ‘tar').
Disadvantages of Coal Tar Epoxies
Coal Tar epoxies smell like tar/asphalt and leave an asphalt like stain on your hands, etc. when working
with the un-cured epoxy. It only comes in a tar black color. Coal tar is not something you want to handle on a
regular basis over a long periods of time.
Most or all of the other disadvantages of coal tar epoxies are often more about the epoxy side of the mixture rather
than the coal tar side. Issues here can include solvents in the product, and poor resistance to UV (becoming more
brittle and chalky), are the ones that come to mind. There are also reports that weathered
coal tar is difficult to recoat or topcoat. At least some coal tar epoxies appear to leave behind an oily
layer as the epoxies weather away and this layer makes topcoating - recoating difficult or impossible. The coal
tar that we use does not appear to have this problem, at least it hasn't been reported to me yet.
Misc. Information
Coal tar epoxies (at least the version we sell) can be topcoated with regular paints. It can also be used
with colored quartz sands or vinyl chips for decorative epoxy floors -just like non-coal tar epoxies are used.
When and Where I Would Recommend Coal Tar Epoxies
The less costly coal tar epoxy is often a better quality coating than an equally priced non-coal tar epoxy. A good quality (and more costly) non-coal tar epoxy will perform equal or better than a coal tar epoxy and will be available in colors other than black. The odor of coal tar epoxies (at least the one we sell) is not really that strong, still, I would use it in a well ventilated area or outdoors. The coal tar epoxies that I have tried (several brands) all seemed flow of the paint brush more smoothly than solvent free, non coal tar epoxies. This makes it a bit easier to apply and probably less likely to leave behind thin spots or ‘pinholes' in the coating surface.
Because coal tar epoxies will bond better than other epoxies to oily surfaces, they are more likely to remain
bonded to ‘degreased' garage or work floors. I would consider their use, perhaps thinned with solvent, as a sealer/primer
over such areas. The coal tar epoxy can then be topcoated with other coatings.
The much flex (bend) and elongation (pull) of coal tar epoxies (3 to 10 times the amount of regular epoxies and
the only product we carry with BOTH flex and elongation - each about 25%) ) is its greatest characteristic and
the case presented regarding the benefits of this property when used on garage floors, garage ramps, etc. where
there is lots of rubber tire traffic, makes logical sense to me. However, I have not heard of less flexible, non
coal tar epoxies failing in these situations either. Coal tar's ability to withstand moisture (old time sailors
sealed their boats with tar pitch) is another important plus, but I think good quality, non coal tar epoxies offer
just as good moisture sealing.
Coal tar epoxies are ‘out of style' but their usefulness has not diminished. A good quality coal tar epoxy offers
a price to performance ratio that is hard to beat. Their greater flex is a real plus (although not as important
in may situations as it might seem), while their messy tar staining and smell are a downside consideration. I think
the decision to use coal tar epoxy can be made more on personal choice than on a point by point technical comparison,
sort of like decision between an apple or orange with your lunch. Just remember that all coal tar epoxies (like
all other epoxies) are not the same.
Coal Tar epoxy alternative is our black CM 15 epoxy paint - find both Coal Tar and CM 15 in our catalog - CLICK HERE
All coal tar epoxies are not the same!
Materials Performance magazine dec. 2002 - q&a section page 39
"Coal tar epoxy failure"
RE: coal tar coating failure in a sewer pump station steel wet well. After suitable surface preparation surface
was coated with two coats of a polyamide coal tar epoxy. Failure of the coating was at a 5 inch zone at the top
of the high liquid level. Failure consisted of softening and swelling, not blistering. The authors go on to quote
from "Corrosion Prevention by Protective Coatings," a text by C.G. Munger. Munger states that CTE (coal
tar epoxies) coatings are most effective in the sewage industry. However he qualifies this by stating that the
amine cured CTE system is essential because of the bacterial attack on the polyamide curing agent.
The coal tar epoxy offered by Progressive Epoxy Polymers IS an AMINE cured system and not the problem causing amide
system described above. Our coal tar epoxy is also solvent free (0% VOC).
| CLASSIFICATION | PROFESSIONAL QUALITY "B GRADE" MAINTENANCE COATING - THIS IS A HIGH QUALITY COAL TAR EPOXY |
| % VOC | 0% VOC, 100% SOLIDS |
| SHIPPING/EXPORTING | HAZMAT - ORM-D TO SHIP. CANNOT BE SHIPPED OUTSIDE THE USA OR BY AIR |
| VISCOSITY | BRUSHABLE, ROLLABLE |
| STND COLORS | BLACK |
| WET APPLICATION | APPLIED TO DRY SURFACES |
| MIX RATIO | 1 TO 1 BY VOLUME |
| STND PACKAGING | STANDARD PACKAGING IS 2 GALLON UNIT |
| MISC. INFO | |
| PRIMING | |
Knowledge is Power - We like informed consumers!
Learn the basics of epoxy at our educational EPOXY 101 page - Click Here.
Finally, email us back with your questions or comments before you buy - EMAIL HERE
Visit our Chemistry of Epoxies site.
Our product contains a blend of curing agents including Cycloaliphatic curing agents - CLICK HERE for more information.
#####
Progressive's Black CM 15 is a modern 'equal' to our coal tar epoxies (but yes, we have coal tar epoxies too!) CLICK HERE
.. CLICK HERE TO GOOGLE SEARCH OUR ENTIRE WEB SITE FOR KEY TERMS/WORDS ..
Already know what you want?
Goto our 1-line product/price summary page MARINE or INDUSTRIAL
Product data sheet and MSDS available
- CLICK HERE
Return to Progressive's boating site (coal tar and other epoxies)
Return to Progressive's commercial site (coal tar and other epoxies)
