Base coats & primers
11 products · 11 ready to ship
Adhesion is settled before the finish coat is opened. This layer reads the substrate: a primer on rusted or factory-finished metal, a wash primer on EPDM, a single-ply base coat on weathered membranes, an MB base coat on cap sheets, a primer on concrete. Under Silicone44 there is no base coat at all.
Start with these
Why this range
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A primer for each substrate
Two metal primers, an acrylic concrete primer, a water-based wash primer for EPDM and a black asphalt primer that revives dried-out smooth BUR and modified bitumen. The substrate picks the primer, not the other way round.
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Base coats carry the reinforcement
The base coat is where polyester fabric and seam tape get embedded at seams, fastener rows, penetrations and flashings, so the detail work is inside the system rather than sitting on top of it.
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Base coats belong to acrylic systems
Every base coat here goes under an acrylic finish coat. Uniflex puts no base coat under Silicone44: it takes a primer only on rusted metal, on EPDM and on asphalt that may bleed through.
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Restoration instead of tear-off
Applied over a sound, dry roof, a restoration system adds 10 to 15 years of service life, and the prep layer is where that either happens or does not.
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Pails, drums and totes
Everything comes in 5-gallon pails. KST041320 and KST041510 also come in 55-gallon drums and 275-gallon totes, and KST041520 and KST042200 in drums with the tote ordered in; the metal primers, the asphalt primer and the other base coats come in drums.
Where it's used
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Screw-down and standing-seam metal
Steel and aluminum panel roofs: rusted areas take the rust-inhibitive primer under either system, and pre-finished fluorocarbon (Kynar) panels take the acrylic white metal primer under an acrylic finish.
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Weathered single-ply membranes
EPDM, TPO, PVC and Hypalon under an acrylic finish take the gray single-ply base coat, with the wash primer first on EPDM only. Under Silicone44, EPDM takes the wash primer and no base coat; weathered TPO and PVC take neither.
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Smooth BUR, modified bitumen and cap sheets
Built-up and modified bitumen roofs, including granular cap sheets, under a white or gray modified bitumen base coat and an acrylic finish coat.
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Concrete roof decks
Cured concrete decks and parapets, primed under an acrylic finish with the acrylic concrete primer, which is listed for surfaces with a pH of 6 to 13. Under Silicone44, clean cured concrete takes no primer.
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Sprayed polyurethane foam and detail work
SPF roofs and the metal and concrete details around them, where the gray elastomeric base coat is listed as a base coat or as a finish coat.
How to choose
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Which metal primer?
KST034520 is the red alkyd rust-inhibitive primer for iron, steel and other metal where corrosion is the problem, and Uniflex primes every rusted area with it under Silicone44 too. KST036520 is the white acrylic version for the acrylic system, and its substrate list includes pre-finished fluorocarbon (Kynar) metal roofing.
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Single-ply under an acrylic
KST038620 is a clear, water-based wash primer for EPDM only, not for TPO, PVC, Hypalon or white EPDM. KST041321 is the gray cross-linking acrylic single-ply base coat for weathered EPDM, Hypalon and TPO, topcoated with an elastomeric finish coat; TPO, PVC and Hypalon are pressure washed before it instead.
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What goes under Silicone44?
No base coat. Rusted metal takes KST034520, EPDM takes KST038620, and asphalt that may bleed through takes Uniflex's Bleed Blocker Primer, which we do not stock: ask on the quote. Foam, cured concrete, weathered TPO and PVC and sound old coatings take the silicone directly, after an adhesion test.
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Base coat or finish coat?
KST041320, KST041520 and KST042200 are gray coats the data sheet lists for either role, on metal, concrete and polyurethane foam. KST041510, KST041512 and KST041321 are base coats only and must be topcoated.
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Asphalt primer, and why it ships differently
KST020412 is the black asphalt primer that revives dried-out smooth BUR and modified bitumen ahead of an aluminum coating. It is not a required step and not for granulated surfaces. It is asphalt-based and moves as regulated freight, which the quote prices.
Compare models
| Model | Type | Size | Sold by | Lead time |
|---|---|---|---|---|
| KST020412 Uniflex asphalt primer | Asphalt primer | On request | pail | In stock |
| KST034520 Uniflex rust-inhibitive metal primer | Alkyd metal primer | On request | pail | In stock |
| KST036500 Uniflex acrylic concrete primer | Concrete primer | On request | pail | In stock |
| KST036520 Uniflex acrylic rust-inhibitive metal primer | Acrylic metal primer | On request | pail | In stock |
| KST038620 Uniflex Bond-It wash primer | Single-ply wash primer | On request | pail | In stock |
| KST041320 Uniflex premium acrylic elastomeric base coat | Premium acrylic base coat | On request | pail | In stock |
| KST041321 Uniflex single-ply acrylic base coat | Single-ply base coat | On request | pail | In stock |
| KST041510 Uniflex elastomeric MB base coat | Modified bitumen base coat | On request | pail | In stock |
| KST041512 Uniflex elastomeric MB base coat | Modified bitumen base coat | On request | pail | In stock |
| KST041520 Uniflex commercial-grade acrylic elastomeric base coat | Commercial acrylic base coat | On request | pail | In stock |
| KST042200 Uniflex premium solvent-based elastomeric base coat | Solvent base coat | On request | pail | In stock |
Every product
Modified bitumen base coat
2 products pails
Acrylic metal primer
1 product pails
Alkyd metal primer
1 product pails
Asphalt primer
1 product pails
Commercial acrylic base coat
1 product pails
Concrete primer
1 product pails
Premium acrylic base coat
1 product pails
Single-ply base coat
1 product pails
Single-ply wash primer
1 product pails
Solvent base coat
1 product pails
Questions
Do I always need a primer?
No. The manufacturer product data sheet decides it by substrate and by condition, and some substrates take a finish coat directly when they are clean, dry and sound. Send the roof type and what is on it now, and the quote lists only the prep the sheets actually call for.
Does a base coat go under a silicone coating?
No. Uniflex never puts an acrylic base coat under Silicone44, and the base coats here all belong to the acrylic systems. Under silicone the roof takes a primer only where its type calls for one: KST034520 on rusted metal, KST038620 on EPDM, and the Bleed Blocker Primer on asphalt that may bleed through, which we do not stock. An adhesion test on every silicone job settles the rest.
What is the difference between a primer and a base coat?
A primer is a thin coat tied to one substrate, there to give the system something to grip. A base coat is a full elastomeric coat that builds film and carries the fabric and tape at the details. Some products here do both jobs; the ones that do are called out under Choosing.
Can a base coat be left as the top layer?
Not the modified bitumen base coats or the single-ply base coat. Both must be topcoated with an elastomeric finish coat. KST041320, KST041520 and KST042200 are listed for either role, so check the data sheet for the one you are buying.
Which primer goes on a Kynar roof?
Under an acrylic system, KST036520, the white acrylic metal primer: pre-finished fluorocarbon (Kynar) metal roofing is on its substrate list along with iron and steel. Under Silicone44, an adhesion test decides whether any primer is needed, so send us the roof. The red alkyd primer KST034520 is aimed at rusted metal.
How do I order, and what about freight?
Send the part numbers, quantities, site ZIP and your dates through the quote form. Every price is quoted per project. Stocked material ships in 1 to 3 business days; anything not on the shelf is ordered in and runs 1 to 2 weeks. Drums and totes go by freight, and the asphalt primer and any solvent-based material move as regulated freight, quoted with the order.
About this collection
Coating failures are usually adhesion failures, and adhesion is decided in this collection. A roof arrives with a substrate, a condition and a history, and the prep layer is where all three get answered before a single gallon of finish coat is opened. Everything here is Sherwin-Williams Uniflex, held in stock, and priced against the roof rather than printed on a tag.
Start from the substrate. Rusted metal takes KST034520, the red alkyd rust-inhibitive primer, under either system; factory-finished panels under an acrylic take KST036520, the white acrylic one whose list includes pre-finished fluorocarbon (Kynar) roofing. Concrete decks under an acrylic take KST036500, the white acrylic concrete primer listed for surfaces with a pH of 6 to 13. EPDM takes KST038620, a clear water-based wash primer that cleans and primes in one step; TPO, PVC and Hypalon are pressure washed instead. Dried-out smooth BUR and modified bitumen going under an aluminum coating can take KST020412, the black asphalt primer, to revive the surface; it is not a required step and not for granulated surfaces.
Then the base coat, under an acrylic finish. KST041321 is the gray single-ply base coat for weathered EPDM, Hypalon and TPO, and it must be topcoated. KST041510 in white and KST041512 in gray are the modified bitumen base coats for smooth BUR, modified bitumen and granular cap sheets, and they must be topcoated too. KST041320 and KST041520 are the premium and commercial grade gray acrylic elastomerics, listed as base coat or finish coat on metal, concrete and polyurethane foam, and KST042200 is the solvent-based gray in the same dual role. None of them goes under Silicone44: Uniflex’s silicone specifications go from the prepared roof straight to the silicone.
Prep, reinforcement and top coat are bought together. Detail the seams and fastener rows with Reinforcing fabrics & seam tapes, close the splits, blisters and low spots with Patch & repair, and pick the top layer from Elastomeric & silicone finish coats. Send the whole list through the quote form with the site ZIP and your dates, and a person prices the system and the freight together.
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Pricing a project?
Send the area or the quantity and the site ZIP, and we reply with one delivered price. We reply within one business day.