Application Tips for Contractors Liquid Rubber is a two component solvent solution version of the single ply EPDM membrane rubber. Its physical properties and method of cure make it unique among liquid applied coatings. The unique combination of properties of Liquid Rubber include:
- Can apply up to 35 mil dry film in one coat.
- Penetrates into cracks and crevices.
- Can go directly over a tightly rusted surface without a primer.
- Cure is not affected by relative humidity. "Freezing does not damage uncured coating.
- Can withstand ponding water or immersion indefinitely.
- Tolerates a wide temperature range from minus 60°F to 300°F.
Liquid Rubber has application and spray characteristics that are considerably different from other types of liquid coatings. Although Liquid Rubber has a heavy consistency, it will self level and penetrate small crevices and pores. It is also harder to brush and more difficult to atomize for spray. The two efficient methods of application are: For Flat Surfaces (flat or low slope) First, catalyze the rubber: Pour a quantity on the surface and broadcast with a rubber edged squeegee. Follow this with a short-knap roller (lint free mohair) to evenly distribute the wet film. Spread rubber at no more than 45 sq. ft. per gallon.
Spraying A.) Equipment: Use a 3.0 gallon per minute airless spray pump capable of developing a minimum 3,000 psi outlet pressure; 3/8 inch ID hose or larger with a max length of 100 ft. Tip size of .015 or .017 for smaller pumps and a .019 tip for larger capacity pumps. Use a 100 mesh strainer at the outlet of pump or in handle of gun. Use a swivel fitting at the gun in place of a "whip" in order to reduce the pressure drop through a smaller ID hose. B.) Thinning: It will be necessary to thin Liquid Rubber with xylene solvent before it can be sprayed. The amount of xylene needed will vary depending on pump size and material temperature. The following is a recommended starting point procedure for thinning a 5-gallon pail: 1.) Add one gallon xylene to pail and mix until uniform. 2.) Add entire amount of catalyst supplied. Mix thoroughly. 3.) Transfer ½ contents to another pail. 4.) Start pump and check spray pattern. If spray is too coarse, try a .015 tip. If this still isn't enough improvement, then add another quart of xylene to the 2 1/2 gallons of rubber in the pail. Once an acceptable spray pattern is achieved, use the same amount of xylene to dilute each succeeding pail. Pour newly mixed rubber into pail under the pump as needed.
Trouble Shooting Procedure Poor spray pattern and clogging of the tip are the most frequently encountered problems during application. These can invariably be traced to inadequate flushing and poor maintenance of the equipment. Check to make certain the 100 mesh strainer is clean before starting. Problem: Poor spray pattern. Solution: Follow thinning procedure in B.) Problem: Still getting a poor spray pattern, even after thinning rubber with 1 ½ gal of xylene per 5 gallon pail. Solution: Starting at gun, successively remove one component at a time, (i.e. tip, tip extension, gun filter, gun, strainer at pump, etc.) and check flow. With tip removed, the material flow should be steady and strong (discharge into pail at pump.) If tip extension is removed and flow increases notice- ably, the ID of the extension is too small. Remove or replace. If discharge stream is weak and pulsating, attach gun and open drain cock at strainer to see if condition is the same there. If pulsation persists, the problem is in the pump. (The balls are not seating properly or are dented and need replacing.)
How to Achieve Minimum Dry Film Thickness Liquid Rubber must be applied at a rate that will produce a minimum dry film of 20 mils. This can be accomplished in one coat by applying the rubber at a rate of 200-220 sq.ft. per 5 gallon pail if undiluted. (6 or 6½ gallons when thinned with xylene.) The actual (expanded) surface area must be used for this calculation.
Example If expanded area of a ribbed or standing seam roof is 1.2 times the length and width area calculation and 1.5 gallons of xylene thinner was used per 5 gallons of rubber, how much material will a 3,000 sq.ft. roof require? 3,000 sq.ft._X 1.2 = 3,600 = 16.36 pails X 5 gal = 82 gallons 220 sq.ft./pail 220 undiluted 16.36 pails X 1.5 gal xylene/pail = + 24.5 gal xylene 106.5 gal diluted rubber Spread Rate The spread rate of 220 sq.ft. expanded area per 6.5 gallons of diluted rubber (5 gal rubber + 1.5 gal xylene) is adjusted to the length X width roof dimension. 220 = 183 sq.ft of roof area (L X W) therefore: 1.2 When 6.5 gal of diluted Liquid Rubber are applied to 183 sq.ft. (LXW) of roof, an average dry film of 20 mils will result.