This quote was from Lance Walton on 1/16/2013 in topic Roof Coating:

quote:

I don't think that the type of roof is the problem. I contacted the manufacturer of Liquid Roof and they confirmed that EPDM SHOULD NOT be applied over any elastomeric coating on surfaces having a slope less than 3 inches per foot. What can, and does, happen is the elastomeric becomes saturated with the EPDM components and loses its adherence to the roof. This is not a 100 per cent occurrence but it happens enough that I do not want to take the chance.

EPDM is definitely a much better coating than any elastomeric but I would have to completely strip my roof and I'm not into doing that.

It appears that the second best choice is the Anvil if only I can find a source. I won't be able to do anything before March so I still have time to reconsider.

I'm curious:
Rubber roof(epdm) vs elastomeric

What product did you use on your roof?
Rubber or elastomeric or?????
What was the product?
How long ago did you apply?
How has it held up?

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The term elastomeric refers to any semisolid material that can stretch. It is a contraction of "elastic polymer." That said, all the roof coatings we are discussing are elastomers..

For some reason the coating people have apparently applied this term to only synthetic polymers as opposed to the natural rubber varieties. From the time Goodyear developed his vulcanization process for natural rubber, scientists have been adding to the list of polymers.

Acrylic, butyl, polysulfide, Neoprene, EPDM, nylon, polyethylene, polypropylene, polyurethane, silicone, epoxy and others are synthetic molecules produced by linking small units (monomers) into chains. The resulting chains have different properties, some elastomeric, some rigid, some adhesive. Some are resistant to UV light, some have very high melting points. The possibilities are almost endless and many chemists are still looking for the best polymer for each application. Some are best for adhesives, some for caulks, some for making rope, and some for coatings.

Since the early development of acrylic polymers, many were/are used in paints and other coatings. Acrylic is an elastomer, as are rubber compounds and epdm. Acrylic is fairly UV resistant, but epdm is better. Most natural rubber compounds are not very UV resistant.

For roof coatings, the mfrs are looking for a strong membrane, waterproof, UV resistant, with good adhesion. Since no polymers are ideal, they choose based on properties vs cost. Some add fibers for strength and bulk, some add UV blockers, pigments or silicones to improve the properties.

Personally, given the incredible variety of formulations available, and the ongoing evolution of the polymer industry, I would choose a product based on the experience of those who have tried them. Sadly, as in paint, there are many ways to make a product cheaper but not better.

The 2013 experience reported with epdm may not apply today. The additives used in the epdm compound are not the same as they were then. The coatings mfrs have each created hype for their own products, so it is hard to know what to believe.

High quality products containing acrylic, epdm and urethane are all available. Research and experience are valuable to choose which is best. Simply choosing "elastomer" is a vast oversimplification of their properties.

I used Anvil 8800 on my Monarch. 3 coats with a roller. Very white, very shiny. So far, so good.

https://www.barthmobile.com/eve...723934597#2723934597

Good luck with whatever you choose. As with paint, so much depends on the surface preparation.

Wow!! Thank you for that very clear, informative, easy to follow explanation. Considering school was not my strong suit I appreciate your understanding of the products & the industry. Were you a teacher?

The most important statement being which I've learned the hard way:

quote:

so much depends on the surface preparation

Tere

Yeah, a chemistry teacher.... can you tell? (Sorry, can't help myself. Trying to relate weird science with familiar backyard stuff! Spent years trying...)

Studying polymers is so cool. You know, if you make them from amino acids, they are called proteins....

BTW: EPDM stands for Ethylene Propylene Diene Monomer. This monomer forms nice cross linked chains and makes really tight membranes. Derived from polyethylene and polypropylene (milk jugs, cheap leisure suits and rope) which like nylon do not stretch a lot and are used mainly for fibers.

Epdm is really good stuff. Developed for use as membrane liners for toxic waste pits, with low permeability. Very resistant to UV and weathering, strong and flexible it is very good for many applications. Weak points: It is not as high as some in adhesion and cannot stand oil and grease.

Anyway, the coatings business is evolving all the time. Choosing the best product is no small task!

You got the most important part: surface preparation! No such thing as too clean!

No clean is too clean, shades of Quant and qual, the dish washing courses for chemists. BA Chem, 1969
Thanks for the nice explanation.