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Sealing in Paint

Can I use Behr Water Based Polyurethane to clear coat Behr Ultra Exterior Paint? Do I even need to clear coat at all?
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Posted 2020-03-25T06:19:54+0000  by Kevin023 Kevin023

Hey Kevin023,

Thanks for your question and welcome to the community.

Any exterior grade paint you properly apply over a surface already has properties in it to give it a long lasting finish.

In other words, any 'sealing' you do of any clear coat will be redundant and not necessary, unless you wish to waste your own time and money.

In the case of Behr Ultra, it has a lifetime warranty on its finish and anything additionally placed over it would and could do more possible harm than helping. 

Never clear coat over an existing new painted finish regardless of where it is located, provided you used the proper paint and used it as directed.


Posted 2020-03-25T16:48:45+0000  by Joseph_HD_ATL
Acrylic/latex exterior paints and coatings are made differently to allow for the extremes of temperature and humidity. To this extent, they are very elastic. There is always a danger of bonding another coating to them that is incapable of expanding at the same rate. There are scenarios where the bond of the paint  to the substrate can actually be broken, causing massive peeling or wrinkling of the paint .
I fully agree with Joseph's answer as to a top coat being unnecessary. However, if you choose to proceed, only use a water based Spar urethane, not an interior urethane. Again, exterior Spar urethanes are concocted to be more elastic, as they must expand and contract with the substrate. They also usually have a UV blocker in them too. Interior urethanes are very hard and brittle, much like oil paints, which is why it is not a good practice to put acrylic on top of siding which has had years of oil paint. An acrylic wants to expand, the brittle oil paint can't, and disaster can occur.
Posted 2020-04-05T06:21:09+0000  by ordjen
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