Frequently Asked Questions
Liquid Roof® and EPDM Liquid Rubber®


What Is EPDM Rubber?

EPDM is a synthetic rubber polymer made from ethylene and propylene monomers. It was developed in the early 1960′s and is used in radiator and steam hoses, freezer gaskets, tires, roofing membranes and aircraft seals to name only a few applications where EPDM is superior to other materials.

Why is Liquid EPDM Rubber the Best Choice?

EPDM Rubber has been used in sheet form for more than 30 years. It is probably the most durable roofing product ever developed. Liquid EPDM Rubber is nearly identical chemically to the sheet EPDM but with the distinct advantage of being liquid. EPDM is unique among rubbers in that it is UV and ozone stable; it has superior water resistance; and can tolerate extreme cold to –62° F. as well as heat exposures exceeding 300° F.

Liquid Rubber vs. Hypalon

Liquid EPDM coatings can be used in place of Hypalon coatings for nearly all applications. The only exceptions would be when coating over damp surfaces or when a class A fire rating is required. The big advantage of the Liquid EPDM coating is the higher solids content. It would require three coats of a Hypalon coating to equal one coat of liquid EPDM.

What is Liquid Roof®?

Liquid Roof® is a liquid version of EPDM rubber marketed for the RV industry. It cures by chemical reaction at ambient (ordinary) temperatures to form a flexible rubber membrane. A pre-measured catalyst is added to the rubber compound before application. The liquid form makes it possible to apply EPDM rubber to many materials regardless of their shape.

What is Liquid Rubber®?

Liquid Rubber® is a liquid version of EPDM rubber marketed for commercial/industrial applications. It cures by chemical reaction at ambient (ordinary) temperatures to form a flexible rubber membrane. A pre-measured catalyst is added to the rubber compound before application. The liquid form makes it possible to apply EPDM rubber to many materials regardless of their shape.

I notice that your company makes both EPDM Liquid Rubber® and
Liquid Roof®.  What is the difference between EPDM Liquid Rubber® F9981 and Liquid Roof® F9991?

Liquid Roof® is designed for a smaller roof such as recreation vehicles. F9991 Liquid Roof is only sold through RV dealers and our Internet Distributors.  Liquid Roof® has a 5-year warranty (see warranty provisions) Liquid Roof® only comes in white. Liquid Roof® is a slightly off-white color

EPDM Liquid Rubber® is a commercial version (designed for larger roofs) but could be used on RV’s.  Liquid Rubber® is sold directly from our factory or through our Internet Distributors. Liquid Rubber has a 2-year warranty unless applied by a certified applicator.  (see warranty provisions) Liquid Rubber® comes in three standard colors F9981 (white), F9999 (black), F9988 (gray). White Liquid Rubber is a slightly brighter white than Liquid Roof®. Both products will perform the same i.e. waterproof your roof and keep the interior cooler etc.

What equipment is needed and how are Liquid Roof® and Liquid Rubber® applied?  Below is a short synopsis of the application procedures and the equipment needed….please click here for complete instructions. 

Quart and Gallon containers:
3/8 inch electric drill
Quart/Gallon mixing shaft
Short nap roller
(6 inch) brush
rubber edged squeegee
masking tape
paint thinner for clean-up

Four and Five gallon pails
1/2 inch electric drill
Pail mixing shaft
rubber edged squeegee
Short nap roller
(6 inch) brush
masking tape
paint thinner for clean-up

Application procedure

1) Incorporate supplied catalyst using drill and mixer shaft by following label directions. When temperatures are mild you should allow the product stand at least 1/2 hour before using.

2) Apply masking tape to perimeter of roof or wherever straight edges are desired. Tape can also act as catch basin for sags if only one edge is attached to roof and rest is formed into shape of a gutter.

3) Pour some material on roof and use squeegee to distribute over surface. Follow with roller to even out the wet film. Product will self-level when sufficient material has been applied. On an RV use a brush around vents, ladder, and antenna. Brush and roller marks will disappear when sufficient material is applied. Work from front to rear.

4) Masking tape should be left on until rubber is solid enough to be touched.

How long will it take for the Rubber to cure?

Cure time is controlled by temperature. At 70° F. and above it will take approximately 14 hours for the rubber to feel solid to the touch. Heavier films may take longer. The lowest temperature at which any cure takes place is 55°F. At that temperature it would take 3-4 days for the rubber to feel solid to the touch if the wet film was not more than 35 mils. Thick films take longer to cure.

Must the air/surface temperature be above 55°F before Liquid Roof® or Liquid Rubber® can be applied?

No, but temperatures above freezing are preferred for physical comfort. Liquid Roof® and Liquid Rubber® will waterproof as soon as they are applied but no cure will take place until the temperature exceeds 55° F.

What effect does high relative humidity or freezing temperatures have on Liquid Roof® and Liquid Rubber®?

Liquid Roof® and Liquid Rubber® can be applied under high humidity conditions as long as the surface is dry and its temperature is above the dew point. The solvent evaporation is governed by temperature only and is not influenced by relative humidity. If the temperature drops below freezing after Liquid Roof® or Liquid Rubber® have been applied no damage will result. The rubber will slowly stiffen as the solvent evaporates and begin to cure when the temperature exceeds 55° F. The ultimate physical properties of the rubber membrane will always be the same regardless of the length of time needed to reach the full cure stage.

How much time is available to work with Liquid Roof® and Liquid Rubber® after the catalyst has been mixed in?

On a hot day, above 80° F., the working time will be approximately four hours until the rubber becomes noticeably thicker and more difficult to apply. Working time is considerably longer at lower temperatures. The rubber will thicken faster in direct sunlight and when liquid level is low in the container scrape liquid from sides. Put container in a cool place when longer working time is needed.  If material is refrigerated (below 50 degrees F.) after catalyst was added it can be saved and used even weeks later.

How soon can I use my RV after applying Liquid Roof®?

As soon as the rubber has solidified and surface is not tacky to the touch.

What are the acceptable substrates to be coated with Liquid Roof® or Liquid Rubber®
The following are recommended substrates to coat:
EPDM Rubber Membrane, Concrete (except foot traffic surfaces), Urethane Foam, Primed Wood, Fiberglass, PVC Sheet and Pipe, Acrylic Sheet, Sponge Rubber Insulation Metal:  Coated or Galvanized Steel, Weathered Aluminum, Weathered Copper

What are the substrates Liquid Roof® & Liquid Rubber® should not be used on? Built up Asphalt Roofs, Asphalt  Shingles, Modified Asphalt Rolled Roofing, Stainless Steel, Glass, Silicone Caulk, Foot Traffic Surfaces, Hypalon Membrane

The information presented herein is furnished free of charge and is based on technical data that Pro Guard believes to be reliable. It is intended for use by persons having technical skill and is at their own discretion and risk. Since conditions of use are outside our control we make no warranties, express or implied, and assume no liability in connection with any use of this information. Nothing herein is to be taken as a license to operate or a recommendation to infringe any patents.


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