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clear coat over latex paint forout door use

Hi

I just finished up a sign I used latex paint. I would like to clear coat it. It’s a outdoor sign I would like to get it to last many years. Any suggestions as to which product would work the best.

Chris

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Posted 2010-12-04T00:14:55+0000  by cameti cameti
 
Hello Again Cameti!

We go round and round on questions like yours, so a summary statement might help bring us back toward the focal point.

Question: What clear coat can be used over my exterior signs that are painted with latex (water-based) paint?

Answer: Very few and none that are oil-based.

How to proceed:

1) Follow Paul's advice and use your preferred sheen (satin, semi-gloss, or gloss) in exterior paint ... no clear coat is required; or

2) Follow Christine's advice and use Rust-Oleum Painter's Touch Clear Gloss ... an interior/exterior water-based clear coat.

The first recommendation is the most simple. Paint with the preferred gloss using exterior paint.

The second, water-based exterior polyurethane, will work over water-based paints while most oil-based urethanes are recommended only for coating an oil-based paints ... as well as wood.
Posted 2014-07-10T23:18:01+0000  by Pat_HD_ATL

Thank you -- very authoritative response.  After I returned the Helmsman unopened I was going to try the Rustoleum clear spray mentioned in one other post here. Though, I suppose it won't have the flexibility of the exterior urethanes.  The painted enamels on the sign do still have quite a gloss to them -- I suppose I should steel wool or fine sand them if I go with your Varathane recommendation.   Even the Helmsman can instructions make quite a point of saying that prior paint should be sanded off totally or at least roughed up using 200 grit sandpaper and also ask that 200 grit sanding be done between coats of the Helmsman.

Posted 2013-10-22T03:52:40+0000  by Measuretwice

 

 

With all due respect to the Minwax rep, it is nonsense to say that Helmsman should only go over bare wood. Were that the case, additional coats of Helmsman would be ill advised too! They are correct, however,  in saying that it will impart a definite yellow tinge to what ever it covers.

 

If you want to try a durable clear coat, I would suggest you try the water based Varathane exterior spar urethane. It remains crystal clear and has sun blockers in it, as does Helmsman. Urethanes are a little touchy about what they will stick to, including to themselves. To this end, it is always a good idea to scuff sand the surface being covered, either with fine sandpaper or a 3M scrubby pad. It does not matter that the surface gets dull, as the urethane will impart its own sheen to everything.

 

I do agree with the above poster that a  good exterior housepaint, such as Ultra, should in itself be sufficient to give long years of service. Acrylic paints, unlike oil paints, also form a flexible film, able to flex with seasonal expansion and contraction of wood.

 

Musings of an ol' paint contractor.

Posted 2013-10-22T00:40:42+0000  by ordjen

Just got off the phone from Minwax/Helmsman.  I have a yard art sign whose paint has cracked in a few places after several years outside.  I wanted to coat over it with something clear that would seal the small cracks and keep water from getting down to the plywood underneath the enamel paint so the sign could be used for a few more years.  I thought Helmsman would be the perfect choice with its claim that it stays flexible and gives with the natural expansion/contraction of wood that has cracked the sign’s enamel.  I also liked the idea that its UV blockers would stave off yellowing of the clear coat with age.  But apparently it isn’t recommended.

The yard art sign is a snowman (complete with hat, scarf, facial and body features) painted on plywood with what appears to be  gloss enamels -- white enamel overall for the background and enamels in red, black, blue, etc. for the details and shadings over the white.  There is also a ruler painted over the snowman so the sign can be used as snow-depth gauge.  Home depot, by the way, sells blanks for this type of yard art.

The lady at Minwax/Helmsman claimed that Helmsman urethane spar varnish should only be used over bare wood.  She claimed it would significantly "Yellow” whatever it was painted over and, more importantly, would be short-lived and flake off as it needs the bare wood for adhesion.

Posted 2013-10-21T15:01:52+0000  by Measuretwice

If you used exterior paint (hopefully satin or semi-gloss), you shouldn't need to clear coat it with anything. Exterior paint is made to go on as the topcoat. It's on your house for years before you decide to paint it again. Especially, if you use a good quality paint like Behr Ultra. The Nanoguard technology creates a very dense, durable paint film that will withstand the elements for years.

 

Typically, the clear coats used outside won't last as long as the paint. 

Posted 2010-12-19T20:44:16+0000  by Paul

Hello Chris,

 

My name is Christine. I work at The Home Depot in Atlanta, and I’ll be helping you with your project today.

 

I have a question for you, what is the sign made out of? If it is wood, you can use Helmsman Spar Urethane by Minwax. Here is a picture of it below:

 

spar.jpg

 

 

You can choose between a satin, semi-gloss or gloss finish. This also comes in a spray.

 

If the sign it anything but wood, you cannot use the Spar Urethane. Here are the other options you have:

 

clearrust.jpgclearcan.jpg

 

Choosing between these products will depend on what is easiest for you. Some people prefer to spray, while others prefer to brush on. As far as quality, they are both the same. Both of these only come in a gloss finish.

 

If you choose either of the brush- on options, you will want to make sure that you use a natural bristle brush, a foam brush, or a foam roller. The idea is to make the finish as smooth as possible, and these applicators will ensure the smoothest finish.

 

If you have any more questions, don’t hesitate to ask!

 

Christine 

Posted 2010-12-04T12:37:51+0000  by Christine_HD_ATL
 
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