Maximum time you can leave undercoat before glossing?

Question

I primed and undercoated some exterior woodwork several months ago. I  couldn’t get to gloss it then. Will the undercoat still be ok to apply gloss to or will it have deteriorated?

Guy · Accepted Answer

Hello,

You should, check the condition, lightly key the surfaces and apply another coat before applying the topcoat.

Volodymyr · Answer

If the woodwork has been sitting for several months since you applied the undercoat, it’s worth giving it a bit of attention before going straight on with the gloss. The undercoat itself probably hasn’t completely failed, but over time it will have picked up dust, dirt, and possibly gone a bit chalky on the surface — especially if it’s been exposed to the weather.

Give it a light sand to remove the surface oxidation and provide a key for the gloss, then wipe it down with a damp cloth or tack rag to get rid of any residue. If the coating still feels firm and intact, you can go ahead and gloss straight over it.

However, if you notice any flaking, powdery areas, or bare wood showing through, it’s better to apply a fresh coat of undercoat first. That will give your gloss a solid base and help it last much longer.

Anthony · Answer

Undercoat will be fine asking as there isn’t any marks the top coat shout cover it I would touch it up with primer to be on the safe side

Tomasz · Answer

If you leave it for more than a week (for water-based) or two weeks (for oil-based), you are outside the manufacturer's recommended recoat window.

High Risk of Failure: The bond between the two layers will be weak. The gloss may peel, crack, or delaminate easily from the undercoat.

What to do if you've exceeded the time:

Clean: Wash the surface with a mild detergent solution to remove any grease or grime. Rinse and let it dry completely.

Sand Aggressively: You can no longer just "lightly scuff" the surface. You need to sand it thoroughly to remove the glossy sheen and create a strong mechanical key. Consider using a slightly coarser grit (e.g., 120-150) before finishing with a finer grit.

Tack Cloth: Wipe down meticulously.

Consider a Primer: In severe cases, or if the undercoat has been left for months, it might be safest to apply a fresh coat of primer or an adhesion-promoting primer before your topcoat.

Lee · Answer

Would be safer to re prime it as it might have absorbed some grease dirt ect, re prime it then leave 3-4 hour before glossing

Ben · Answer

Will need to reapply then paint it with gloss but this will depends on how it’s set

Jeff · Answer

I recommend a recoat. If the weather hasn't breached the paint, you could possibly clean and dry it thoroughly to remove any oil stains or potential mould. But the safest course of action for a good finish is a new coat of primer. Best of luck with the job!

Shane · Answer

Unfortunately I would primer again of use zinsser all coat as this product is a primer as will as a top coat

Frincu · Answer

Given the timing, the undercoat will likely have deteriorated slightly. You'll need to lightly sand it, clean it throughly, and consider applying a fresh coat of undercoat before glossing.

Marcus · Answer

Yes you can undercoat before gloss and  then gloss anytime until dirty or dusty but can still light sand and gloss

Maximum time you can leave undercoat before glossing?

Follow Us

Cookies

Manage Cookies

Essential cookies

Analytics & Tracking

Advertising