Oil Stop Primer

Primer OS is a solvent based penetrating epoxy primer that exhibits excellent characteristics for coating over oil soaked concrete.

Primer OS is recommended for petroleum oil contamination only.  This product  has been developed to block oil ‘bleed back’ from oil soaked concrete substrates and provide a primed surface for subsequent epoxy or polyurethane coating systems.


  • Barrier against oil
  • Stops oil “bleed back”
  • Compatible with a wide range of coating systems
  • Can be top coated same day
  • Resists petroleum based oil
  • Chemical resistant

Main Uses

  • Floors
  • Pump pads
  • Trenches
  • Sumps
  • Drains

Surface Preparation

The substrate must be structurally sound. Loose or unsound concrete should be removed and made good. Surfaces must be entirely free of oil, grease, paint, corrosion deposits, dust, laitance or other surface deposits. Any cracks or pock marks should be filled with CoverBond PF160 before application of Primer OS.

Cleaning Oil Contaminated Slabs

Clean the slab using CoverClean HC. Wet the floor by misting the surface with water and then immediately apply the CoverClean HC. The cleaner may be applied by either a pump up sprayer spray or medium bristle brush at a rate of 200 to 250ft² per gallon (4.9 to 6.1 m2/L). For heavy duty cleaning apply at a rate of 150 to 200ft² per gallon (3.7 to 4.9 m2/L).

The affected area must be agitated with a stiff brush. This can be manual or with a power scrubber depending on the size of the area being cleaned. The solution temperature must not be allowed to rise above 120°F (48.9°C) or to completely dry out. Water must be present at all times, since this is the source of oxygen for the microbes.

Allow the CoverClean HC to sit for a minimum of 3 hours. Keep wet during this time and agitate one more time, 20 minutes before rinse off. If the product cannot be rinsed to a drain, then use an auto scrubber or similar to wet vac up the liquid.

Allow substrate to dry before applying Primer OS


Mix Ratio 1:1 by volume.

Condition the material so it is at a minimum temperature of 60°F.  Add 1 Part B in to 1 Part A and mix using a slow speed drill and paddle for 4 minutes until both components have fully dispersed and are uniform in color.  Be sure to rotate the mixer throughout the pail.


Make certain that the floor temperature and air temperature is between 60 and 90°F.  Apply product by 3/8th solvent resistant non shedding roller or brush at 200 ft2/gal (8 mil thickness when wet).  Too thick of an application may result in product failure.

Top coat or recoat

Primer OS can be top coated with epoxy and /or urethane systems  within the recoat window (3 to 12 hours at 77°F). We recommend 1 coat of Primer HS and 2 coats of CoverShield U270 (see separate data sheets and color chart for color options). If different topcoats are desired, contact CoverTec for application details before proceeding. Proposed intermediate and topcoat selections should be evaluated for adhesion and compatibility.  A representative sample patch should be applied for this purpose.