Can Primer Be Used as the Finish Coat When Painting?

I am planning to paint my shed. Could I use some leftover primer as the exterior finish coat? -Aaron

Hi Aaron,

Primer is not formulated to stand up to the elements and should be topcoated within several weeks to ensure proper bonding. If left uncovered for an extended period of time, primer will tend to deteriorate and chalk, which could prevent future coats of paint from adhering properly.

Also, primer comes with a flat sheen to promote bonding between the substrate and top coat, which does not hold up as well to sun, rain, and dirt as satin or glossy paints.

Good luck with your project,



  1. To be more specific…I painted my room with a primer and then a finished coat. After a few thoughts, I realized that I like the colour of the primer more. Is it possible to repaint the room with the primer over the finished paint?


    • Hi Jacky,
      While primer should not be used as a finish coat, you could paint a scrap with it, let it dry, take it to a paint store, and have the color and gloss matched to a finish paint.

  2. I stripped my cedar siding to bare wood and then put a coat of oil based primer on it. That was 3 months ago. We have had hot, dry weather since then. What do I need to do to prepare it for painting in the next couple of weeks?

    • Hi Barbara,
      Since some outside primers can degrade over time if not painted promptly, read the label carefully (or contact the company that made it) to see if they indicate a time period during which the primer should be topcoated. If your primer has been on longer than that, you might need to apply another coat of primer before topcoating. Good luck with your project.

  3. Hello,
    My boyfriend has just painted the bedroom with primer. I am trying to talk him into putting a finish coat over the top, but I don’t have any solids reasons to give him as to why that needs to be done. So I’m hoping for a good explanation of why primer cannot be used as a finish coat. Also, primer was applied to the interior of the downstairs about a year ago. Do we need to prime again, or can we put a finish coat of paint over that?

    • Hi Sara,
      Primer is not formulated to be used as the final topcoat, that includes both inside and out. When left uncoated inside, primer will not clean up well when it gets dirty, will have a no sheen, and isn’t available in a range of colors and sheens. As far as covering over year old primer, it would not be as big a consideration inside as out, where the primer would have degraded over time due to exposure to the elements. If your year old interior primer is in good shape and isn’t dirty or stained, you can probably topcoat over it, though it wouldn’t hurt to prime it again. In the future you might want to consider some of the new paints that combine a primer and topcoat in one such as Behr Premium Plus Ultra, which we did a Best New Product segment on. Good luck with your project!

  4. Exterior latex primer that was applied to our home a few weeks ago is turning yellow. Will the yellowing get worse over time if the topcoat isn’t applied? Other than the yellowing, what other problems can occur if this primer is left uncoated? It may be a while before we can apply the topcoat since the weather is now too cold to paint.

    • Hi Jennifer,
      As Danny’s article above says, primer that is not topcoated over within a few weeks can chalk and degrade over time, resulting in possible failure to adhere properly to the topcoat when it is applied.

  5. I am preparing to paint a block wall that has old white paint on it,that is weathered a lot. Do I need to use a primer and if so what kind. This wall is 5ft high and sees a lot of sun and rain

  6. Hi,
    I am repainting our dining table and chairs to a lighter color.I already applied a coat of primer, however,it looks very thin to me,is it OK to apply another coat of primer?Thanks

  7. We replaced the T-11 siding (fir) on one side of our house in early June. We started applying oil-based primer but it got so hot that the primer was the consistency of glue. We tried some additives to thin it out and, over the course of the summer, we got most of the surface covered when weather permitted. (We also had a lot of rain this summer, besides being extrememly hot.) We still have some small areas to cover around where the electric lines, telephone, etc. come into the house – plus some of the grooves in the T-11.

    We looked at the can last night and now we see that we should’ve applied the top coats within 30 days of applying the primer! After reading your advice to Aaron, we understand why but we’re not sure how to proceed from here. Should we go ahead and apply the primer to the remaining raw wood before winter or are we wasting our time and the primer? Will we need to remove and reapply the primer next year before we apply the latex paint we plan to use for the siding? What is your advice? Thanks!

  8. 20 years ago my dad used Benjamin Moore’s exterior latex primer on the stucco walls of my house without using any topcoat. Still looks good and has held up amazingly well. I guess the primer alone might look a bit chalky and the brushmarks show more, and is not quite as abrasion resistant as a paint finish, but on rough stucco surface you can’t really see it and the stucco area starts at the 2nd story where nothing touches it or rubs against it anyway.

  9. Hi i have built some fenders out of wood for my trailer. I didn’t realize i was not putting primer first instead i was putting the actual exterior paint the last coat i put on was the primer/sealer. I am going to put a coat of regular exterior paint on top but underneath is it OK if i just leave it like it it with just the regular exterior white paint?

  10. I have a pressed wood bathroom cabinet that needs painted.Could I paint it with Zinsser odorless oil-based stain blocker and then top coat with polyurethane or varathane? Thak you1d

  11. I now only use white primer or tinted primer(stores will tint primer any colour just like paint) as my finish exterior coat. I’ve used all paint types on my extreme weather, bugs, spiders, great lakes front cottage, oil, latex, and just primer, the primer weather’s just as well if not better than the most expensive paint that I’ve used. I’ve never had any chalking on the 4 rows of cinder block below the siding. I used to think primer was a scam, now I think paint is.

  12. I have some surplus interior trim that is painted and I wanted to know if I can paint over it with exterior paint with primer to be used outside?

  13. The primer looks so good, I don’t know if I want to paint over it. I am refinishing stairs. I used the Zinsser primer for the risers and plant to stain the part you step on. Can I leave the primer as is?

  14. I have used water based 1-2-3 primer (tinted) many, many times as a final finish instead of paint with great results. It has a light sheen which is fine. It is a bit thinner than most paints so you must watch for drips and spatters.

  15. Hello Danny….I was wondering, if I am using a white primer (bullseye 1 2 3) and painting over that with a white paint (Valspar) with an eggshell finish, can I mix the 2 together in equal parts to paint the entire room?

  16. Hi,

    first of all, thank you so much for maintaining this thread, it is very helpful to all of us, lay people.

    I rented an apartment which was painted only in primer. I didn’t realize this at the time, otherwise I would have requested a proper finish. Over time, the walls sprouted innumerable bubbles, and my impression is that finish would have protected the topcoat from moisture buildup. Is that true or I am making up stuff?

    Thanks a million

  17. I have a musty-smelling dresser made of particle board on the inside of the cabinet itself. Could I use an oil-based primer such as Kilz Odorless to get rid of the musty smell on the cabinet itself and not re-paint with a top coat?

  18. Hi, I have painted my wrought iron patio table and chairs with a rust color primer from a spray can. It matches the louvers on our house that are painted with rust color paint. I would like to leave the table/chairs in the primer color since I can’t find that color of spray paint. Can I do this or will this not work in the weather elements.
    Thank you

  19. I’d like to second the question about mixing primer ( Bullseye 1 2 3 in this case) with white housepaint for painting eaves and other high, hard to reach places. I’m not sure that I’m up to painting those areas twice, and I understand about not leaving just the primer on, but what about a mix of, say, 1 part primer to 3 paints?

  20. Put oil base odorless kilz on my textured. Ceilings as I have done before. The ceiling was beautiful. Top coated with valspar latex ceiling paint and all went to crap. The ceiling yellowed all over in areas that had no yellowing before. I have put on another coat of the kilz and is beautiful white again. Should I risk trying to top coat again or leave it with the kilz finish.

  21. I wish i could see responses on this site. As i know you have answered this question before. I like the look of my bedroom after it was primed. The chalk look is in style now. I want to do 2nd coat of primer as finish. Any drawbacks?

    • Hi, Cynthia!
      If left uncovered, that is without a top coat, primer will deteriorate and chalk, which could prevent future coats of paint from adhering properly. (And we imagine it’s not the chalk appearance you would prefer) It’s not recommended. Thanks for your question.

    • Hi, Falk,

      Primer is formulated for bonding in ways that paint is not.
      And certain substrates require a bonding primer, so we do not recommend this.

      Thanks for your question.

  22. Just sanded and applied 1 good coat of dulux water based primer u coat to external wood windows but weather has been very wet, cold and humidity is high, can i leavetop coating with Weathershield until the spring? If so will they require 2nd coat of p/undercoat prior to top coat? Thanks Tony


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