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EPDM Liquid Rubber may be applied on roof decks, gutters, structural steel, air conditioner enclosures, cooling towers, galvanized steel, unit heater flues, smoke stacks and chimneys, fiberglass and non porous masonry surfaces. |
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| Surface preparation |
| All surfaces to be coated should be clean and dry. Remove peeling paint and brittle caulking. Heavy build-ups of asphalt roof cement should also be removed. Tighten any loose fasteners and replace those that are severely corroded. Repair or replace roof panels damaged by storms. Remove heavy rust with abrasive discs or wire brushes. Power-wash all surfaces to be coated and allow to thoroughly dry. Caulk all gaps wider than 1/16 inch that are not expansion and contraction slip surfaces. |
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| Treating rusted areas |
| It is recommended that a corrosion inhibitive primer first be applied to areas where severe rusting has occurred. EPDM Liquid Rubber does not contain any corrosion inhibiting pigments but it is such an effective moisture barrier that it may be directly applied over light rust without a primer. |
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| Going over existing coatings |
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[1] Original mill finish |
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When the original coating is still adhering tightly, it can be top coated directly with EPDM Liquid Rubber. Corrosion inhibitive primer should still be used on severely corroded areas. |
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[2] Alkyd paints |
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Aged alkyd paints that were applied over the original mill finish should be checked for adhesion. If coating is brittle and can be scraped off easily, it must be removed before EPDM Liquid Rubber can be applied. If removal can be accomplished with high- pressure water spray, that should be the method of choice. If removal is spotty, the roof should be allowed to weather another year before removal is again attempted. Brittle alkyd paint will continue to lose adhesion over time and will result in predictable failure if not removed. |
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[3] Asphalt based coatings |
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EPDM Liquid Rubber should not be applied directly over asphalt based coatings. Water based acrylic elastomeric coatings may be used as intermediate coats, on sloped roofs only, before applying Liquid Rubber. Asphalts should be considered as being unstable materials and are excluded from warranty coverage by Pro Guard Coatings. Caution-Latex house paints cannot be substituted in place of the acrylic elastomeric coating. |
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[4] Acrylic elastomeric coatings |
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EPDM Liquid Rubber bonds very well to these coatings. Some of the earlier acrylic elastomeric formulations were prone to the development of under film corrosion. There usually is little visual evidence of this on the surface of the acrylic so small sections of coating must be removed from different parts of the roof to determine whether the condition exists and how severe it is. A visual inspection of the underside of the roof panels can reveal total penetration in the most severe cases. The decision of whether to apply EPDM Liquid Rubber over an area with severe under film corrosion becomes an economic one. The recommendation should be to replace the corroded panels. However, if this is not an economically viable solution and removal of the coating is equally impractical, then application of the EPDM Liquid Rubber may be justified as being the best of the available alternatives. No warranty would apply in such a case. |
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| Application of EPDM Liquid Rubber |
| Airless or Air Atomized spraying is the only feasible application method for corrugated or standing seam roofs. Airless equipment needs only one hose from pump to gun but must generate 3500-4000psi and is limited in the length of hose that can be used because of high-pressure drops. Air atomized equipment requires two hoses to the gun making it more cumbersome to maneuver plus the addition of a compressor. |
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Equipment capable of spraying Liquid Rubber |
| Pump Model |
Max. Pressure |
Fluid Flow |
Hose ID |
Max. Hose Length |
| Graco GH733 |
3500 psi |
3.0 gpm |
1/2 inch |
150 feet |
| Graco GH3640 Roof Rig |
36000psi |
3.8 gpm |
1/2 inch |
150 feet |
| Gun |
Should be rated for spraying mastics. A 30-40 inch tip extension is recommended. |
| Tip Size |
.017 to .021 with a 12 inch fan width |
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Note: Do not use a "whip" between hose and gun. This reduces flow and pressure which results in poor atomization. |
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| EPDM Liquid Rubber will produce greater line drops and spray with a narrower fan than most other coatings. Some solvent (Xylene or mineral spirits) must be used to thin the product to make it spray easier. This dilution should not exceed 5 quarts solvent per 5 gallon pail. The recommended procedure is to spray apply and roll back with a short nap roller to obtain an even film and complete surface coverage. Application should be at rate of 40-45 square feet per gallon. This will produce a 20 mil dry film. The chemical and physical properties of EPDM Liquid Rubber make it possible to achieve a 20 mil dry film on sloped or vertical surfaces with one evenly applied coat. Spray-on followed by rolling where surface configuration permits will produce an even film. Roller marks will level out in a few minutes. |
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| Fasteners |
| Caulking around fasteners is usually not necessary. The physical properties of the EPDM rubber (EPDM Liquid Rubber) will produce a longer lasting seal around fasteners than caulks will because the latter will embrittle with age causing loss of adhesion and cracking. It is good practice to brush the rubber into the fasteners after spray application to ensure complete coverage. This procedure will still be less time consuming than caulking. |
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| Fabric reinforcing of seams and overlaps |
Tight overlaps and standing seam joints do not need to be reinforced.
Overlaps with gaps greater than 1/16 inch and corroded edges should receive fabric reinforcing. Apply a light coat of EPDM Liquid Rubber, center the fabric on the overlap and roll it out taking care not to create wrinkles; press fabric down with squeegee or wide spatula; spray apply a full coat of EPDM Liquid Rubber to seal top surface of fabric and roll back over to ensure coverage. |
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| Over spray |
| If over spray lands on cars, it can be easily removed with Mineral Spirits within 24 hours. Thereafter, stronger solvents such as Xylene will be effective in removing the rubber but may dull some finishes. Black, one-foot square test panels should be placed in various parts of the parking area as evidence of over spray in the event later claims are made. |
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| Flushing Spray equipment |
| Three separate flushes with Xylene are recommended. (Save this solvent for future use). When the last of the EPDM Liquid Rubber is sucked from the pail, add several gallons of Xylene to pail to purge material from line and onto roof. Remove gun from the hose and place end of hose in same bucket as pump suction. Reduce pump delivery pressure and allow solvent to recirculate for five minutes. Remove suction tube from bucket and purge line. Starting with clean solvent or the final flush from a previous cleaning, repeat the procedure two more times. The gun can be reattached during the final flush for cleaning. |
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| Pail handling and disposal |
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Pour material from newly mixed pail into the one from which the pump is sucking. Scrape the sides of the just emptied pail into the next one to be mixed. Only a thin film of material should remain. When this procedure is used, the pails can be collapsed and placed in a trash dumpster or taken to a metal recycler. |
| Rain showers or freezing temperatures |
| Unexpected rain showers after application may affect the surface appearance but will not wash material off roof. Temperature drops below freezing will arrest the cure but will not damage Liquid Rubber. The cure reaction will resume again whenever adequate temperature returns. |
