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Internet #205009921

Model #276049

1 gal. Mold Killing Interior/Exterior Primer (2-Pack)

Includes 2 cans ($34.06 /can)
$68.12 /case
  • Kill existing mold, mildew, and odor causing bacteria
  • EPA registered assures performance quality EPA Reg 87469-1-69587
  • Coating works under any coating, aides in covering fungal stains
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Product Overview

Zinsser Mold Killing Primer is a water-based EPA registered fungicidal protective coating that can be used to paint over and kill all existing mold, mildew, moss, fungi, odor causing bacteria and any other fungal organisms. It prevents the growth of mold, mildew and other fungal organisms on the paint film and is for use on non-porous interior and exterior surfaces.
  • Kills existing mold, mildew and odor causing bacteria
  • Covers up to 450 sq. ft. per gallon
  • Paint over existing mold, mildew, and odor causing bacteria without extensive pre-cleaning. (*Fix all moisture issues. For structurally unsound surfaces, refer to label for remediation guidelines
  • Recommended for residential, commercial and industrial applications including bathrooms, basements, wall cavities, window frames, office buildings, factories and more
  • Dries to touch in 30 minutes, top coat in 1 hour
  • Great for use under any topcoat; ideal with ZINSSER Perma-White
  • For optimal protection, top coat within 72 hours of application
  • For small projects, use ZINSSER Mold Blocking Primer spray
  • Clean up with soap and water
  • Online price includes PaintCare fee in the following states: CA, CO, CT, DC, ME, MN, OR, RI, VT, WA

  • California residents

Additional Resources

From the Manufacturer

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Paint/Stain/Waterproofer Product TypeGeneral PurposeSealerSealerSealer
Primer PurposeColor Changing,Mold, Mildew & Water Damage,Odor Blocking,Sealant,Stain BlockingMold, Mildew & Water DamageSealantColor Changing,Odor Blocking,Stain Blocking
Container Size1 Gallon1 Gallon1 Gallon1 Gallon
Surface Material UseBrick,Drywall,Masonry,Metal,Plaster,Stucco,WoodDrywallCeiling,Concrete/Brick/Masonry/Stone,WoodDrywall
Application MethodBrush,Paint Sprayer,RollerBrush,Paint Sprayer,RollerBrush,Paint Sprayer,RollerBrush,Paint Sprayer,Roller
Paint/Stain FeaturesFast Drying,Low Odor,Mildew Resistant,Mold Resistant,Stain ResistantMildew ResistantSealerNo additional features
Base MaterialWater BasedWater BasedWater BasedShellac
View ProductView ProductView ProductView Product



Container Size1 Gallon


Application MethodBrush,Paint Sprayer,RollerBase MaterialWater Based
Coating Product CategoryPrimerColor FamilyWhite
Color FamilyWhitesColor/FinishWhite
Dry to touch (min.)30 minInterior/ExteriorExterior,Interior
Number of coats recommended1Number per Package2
Paint/Stain Clean UpSoap & WaterPaint/Stain FeaturesMildew Resistant
Paint/Stain/Waterproofer Product TypeSealerPrimer PurposeMold, Mildew & Water Damage
Surface Material UseDrywall

Warranty / Certifications

Manufacturer WarrantySatisfaction guaranteed for full refund of purchase price

Questions & Answers

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Customer Reviews

  • 4.4
    out of 72 reviews
  • 87%recommend this product
Filter by:
Showing 1-10 of 72 reviews
The primer had mold growing on it
I bought this product 5 months ago. I went to use it the second time and it had mold growing all on the surface. Doesn’t seem to work as a mold killer.
Response from Rust-OleumSupportJul 23, 2021
Let's see what we can figure out. Zinsser Mold Killing Primer is used to paint over and kill all existing mold, mildew, moss, fungi, odor causing bacteria and any other fungal organisms, it does not prevent mold from growing on the top coat. As a primer, Mold Killing Primer must be top coated. After priming we suggest top coating with a mold and mildew proof top coat, such as Zinsser Perma-White Mold & Mildew Proof Paint.
- Rust-Oleum Product Support 6 Rustoleum
    Lessons learned
    Considering the problems this product solved for me, the price (thru HD) was excellent. Now to the lessons learned. 1) When you clean your house, you may have invisible mold spores or roots still in the wood/substrate. Clearly I did as I bleached, SCRUBBED, and rinsed the previously sealed cedar siding on my front porch - which is on the NW side/front of the house. I had previously used an alkyd primer and solid-stain (rubbol) on this same cedar siding. Then I minimally touched up using Ben Moore's alkyd primer, following up with 2 coats of Sikkens rubbol solid-hide stain (which I love). This was early June, 2016. About 10 day later, I saw mold growing. When I cleaned the surface, I realized the mold was UNDERNEATH the recently applied rubbol finish. (Looks and feels like silky paint.) It was actually growing underneath and creating darker areas everywhere the siding was below the top-most plane of the surface! 2.) Freaking out, I started researching online and spoke to my paint supplier. This stuff got great reviews from my trusted supplier so I ordered it from HD. Then I brought the cans to my supplier for tinting (HD's price beat my contractor's price but comes in white.) 3.) Early July 2016, I left the original porch covered area alone and continued cleaning the other sides of the house, adding the additional step of the Mold Killing Primer (MKP) before touch-up caulking and reapplying the rubbol finish. In the meantime, the original surface was growing mold again in less than a week. Then I finished the NW side which is not covered by the porch and two separate NE sides of the house. Then I bleached the front porch again - still seeing the darker/grayer areas in the deeper planes of the siding. (Note that the trim, the floor, and the ceiling did not have this same problem as they did not have the texture that the cedar siding did.) Fine, so now I've bleached the area under the 38'w x 8'd x 10'h NW-facing front porch 3X. Mold is still visible beneath the recently applied Sikkens Rubbol Finish. 4.) Then I focus on the rear of the house where I had previously only applied the alkyd primer a few years ago. This time I bleached and pressure-washed the siding, then followed up with the MKP. All seemed great. Then the rains came. I couldn't re-coat the primer due to the monsoon and 8" of rain in 3 days in Central VA. In only 6 days, mold was regrowing on this SE, under-the-rear-porch area of the house. Crestfallen at the reappearance of mold, I realized I was able to wipe off the new mold. So, it was only on the surface of the recently applied MKP. Fine, so got out the bleach sprayer, reapplied solution, and then began to rinse with just a hose, not pressure wash. SHOCK - the primer started to PEEL OFF! Again, calls to my supplier. Turns out, I hadn't waited long enough for the wood to dry out from all the moisture - in the wood, in the primer, in the environment. I left everything alone and persisted in the areas that hadn't gotten wet from the rain. And I waited about 5 more days to re-coat the siding with the MKP and then the Sikkens finish. (I also added a mold inhibitor to each of the gallons of the Sikkens Rubbol finish, especially since it is a alkyd/latex blend and mold LOVES oil-based materials.) Several days after I completed all of that, I tested to see if any of the product was peeling or even able to be scraped off ----NOPE, all adhesion is great! 5.) Now, early October, 2016 - no mold has regrown on any boards that I first covered with the MKP before reapplying the final finish. But it's growing just fine on the front porch siding. So, I moved back to the front porch to finally addressed the subsurface mold. Again, very obvious black mold spores covering about 25% of the surfaces of the siding growing thru from I guess roots left behind from June 2016. So it was 10/11/16, the fourth time I've applied cleaning solution to the siding and the third time I've pressure-washed. The next day - I used my recently purchased moisture meter and got a reading of 2%, knowing that the boards were dry from the pressure-wash. (They would be because they were already plenty sealed, just with mold encapsulated.) 6.) 10/12/16 I liberally applied the MKP to all siding under the porch. It visually concealed the mold more when it was wet but I could sort of see the darker greyish color underneath as it dried. I let it dry overnight. Checking this morning. I can't see mold underneath. It's 10 a.m. and 58 degrees outside. The moisture meter is reading 21% on the recently primed siding. And the can states that the material can be re-coated within 30 minutes and re-coated with any finish. Once the humidity gets a bit higher outside, I will apply the first coat of the rubbol finish. TO SUMMARIZE LESSONS LEARNED * Always pressure wash siding after cleaning to ensure that mold spores that are killed or invisible due to bleach are detached from the substrate. Scrubbing textured surfaces does not ensure removal of all unwanted material. * When reapplying paint, stains, or sealants, seriously consider reapplying some sort of treatment that clears away mold roots and/or mold spores. These items are available in primers, spray treatments, or additives to paints. (Had I done this on the first area refinished, I would have saved the time & material cost of three more cleanings and two coats of finish on the 38' x 10' front porch wall.) * Invest the approximate $50 in a moisture meter to let you know when boards are dry enough to apply solutions according to manufacturer instructions. * Allow the stated amount of time for sealants to dry before adding additional treatments. a.) Had I waited more than one day for the rear porch cedar siding to dry out from the initial clean and pressure wash, the MKP would have had enough time to dry and may not have supported mold on it's surface to begin with. b.) Had I not applied more solution to remove the surface mold on that siding on the rear, the primer wouldn't have peeled off where it did. Where I left it alone to dry, it adhered and I was successfully able to reapply more MKP and 2 coats of finish. All is well today, 2 weeks later on the rear porch. This week, with low humidity, I will complete the front siding, adding the Sikkens Rubbol and reinstalling my beautiful front porch furniture. Then I can sit back with a cup of coffee, and RELAX into Fall, 2016.
    • DIY
    • Recommended
    6 found this review helpful
    I have to write a dissenting opinion. This is latex, not absorbed by drywall, and for me it came off as I was painting!!
    Number one this product is overpriced. There is no way it is worth more than $20 a gallon. True, it did block the water stain and signs of mold, however as you can see it was not absorbed into the drywall. (Note: the primer had been on the ceiling for at least 2 weeks before I started painting.) I used regular ceiling paint with a little bit of added texture to cover any imperfections in the ceiling. Admittedly, it was a bit thicker and heavier than regular paint. As I was about to finish, I noticed a small air pocket where the paint and primer had come loose from the ceiling, as I went up on the ladder that small area got bigger and bigger until finally about 20 square feet had come loose from the ceiling, about the exact area that I used the Zinnser mold killing primer as opposed to my regular Behr primer. Horribly flawed product, and now I have to start over. What more can I say about it?
    Response from Rust-OleumSupportJul 7, 2016
    Something is amiss here, Joshua. Please keep in mind, it is recommended for applications that have existing wet, slimy, heavy soiled, gross filth, overgrowth or loose material on the substrate a pre-cleaning step is required. Physically or mechanically remove gross filth, heavy soil, overgrowth or loose material including dirt, grease, and oily films before application and ensure the substrate is free of slime or excessive moisture to ensure long-term adhesion and product performance. Rustoleum
    • Pro
    11 found this review helpful
    This stuff covers well
    I have two spare rooms that I plan to renovate but I’m not ready to start yet so I’m trying this product out on a scrap piece of wood for now. When I received this there was some paint around the rim by the lid which I thought was a little strange coming straight from the factory. This is quite thick so it puts on a good layer with just one coat, see pictures. It also does not need to have a topcoat on it. It can be recoated in an hour which is pretty good. Because this kills mold and mildew it has pesticide safety warnings on it as well as the normal paint safety warnings so you should take notice and be careful with it. I don’t know how effective it is against mold because I would have to judge that over time and see if any mold comes back. I’m assuming it does the job it says it does. If I see any mold on it later I’ll re-review it.
    • Recommended
    1 found this review helpful
    Watching closely
    We were going to put new counter tops and sinks in both bathrooms. The master bath went smoothly. When it came to the second bathroom. we found a mold when we removed the old counter top from the cabinet. I than removed the cabinet and found mold in the sheet-rock and back and bottom of the cabinet. I removed the cabinet to be rebuilt (since HD guessed $500.00 for a custom built one). After everything was taken out I painted all the studs, drywall back ( other wall) and some of the sub-floor. I hope this stuff works, the new dry-wall I cover the studs will not let me see what is happening inside the wall. The new dry-wall will also be painted (both sides) with this primer. I hope I never see mold in that area again.
    • DIY
    • Recommended
    4 found this review helpful
    Great Investment So Far
    Pulling down the wallpaper in the master bathroom revealed a nightmare mess. The walls were covered with mold/mildew. I read the reviews on this product and decided it was worth a chance. It's a small bathroom so 1 gallon was more than enough to put on two coats and still have some left over. It's been just a month but, so far, there's been no tell-tale return. Prior to this purchase and application, I'd have to scrub my ceiling down with bleach at least a month. Now, it's absolutely sparkling!
    • DIY
    • Verified Purchase
    • Recommended
    13 found this review helpful
    Too Early to Tell
    I used this product recently for two different applications -- both ceilings. In one instance, my bedroom ceiling suffered damage due to a roof leak (see picture), and the sheetrock and insulation needed to be replaced (see picture). I painted the repair with Zinsser Mold preventive paint as a precaution since I was uncertain that all of the damaged and wet building materials above the ceiling had been fully removed. In this case, there were no stains to cover. The paint appeared a little thin for a primer-style product, but it provided reasonable coverage for a "primer" coat. If I didn't intend to apply a finish coat, I would have had to apply two coats of Zinsser for better coverage. In the other instance, I had to cover an area of minor water staining -- again caused by a smaller roof leak in a different area of my house. I had previously covered this same area with a competitive product K***, which when the leak continued, did not hold the stain back. The roof has been repaired in this area too -- now only time will tell whether the Zinsser product will do a better job of covering the old stain than the competitors product did. The product washed up quickly and easily. Nothing I experienced would cause me not to recommend the product.
    • Recommended
    5 found this review helpful
    On the fence about this one
    This is a white water-based primer that has some antibacterial elements. The intent is for a coating to kill and prevent recurrence of mold, mildew, and bacteria. It goes on fairly thick and covers well any mildew stains that are not intense. The real question I cannot answer is the long term result. After one week of applying a coat to some mildew-infected siding, the paint is still clear of the mildew that was underneath and none has reappeared on top. It will be interesting to see how long this lasts. Ordinary chlorine bleach had been used in years past to eliminate the mildew, but it always came back fairly quickly. The key chemical in this product is 3-Iodo-2-propynylbutylcarbamate (IPBC) which is commonly used in some skin cosmetics as a fungicide/antimicrobial. The EPA allows as much as 0.1% in the cosmetics, but they commonly have only about 0.012% concentration. This product has a concentration of only 0.0063%, or a little over half of what is used on your skin. I do not understand why, at least, the 0.1% concentration couldn't be used. So, I suspect this is not as effective as advertised. It would only deliver half as much fungicide/antimicrobial as a coating of Maybelline coverup. Call me skeptical, but for now I'm on the fence about this product, with 3 stars and no recommendation either way.
    26 found this review helpful
    I was satisfied. Thank you...
    I was satisfied. Thank you
        Showing 1-10 of 72 reviews