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  1. #1
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    Jul 2011
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    Default Exterior steel door

    Want to paint front door which is still in original white; are there any specific pre-painting things I need to do, like sanding, etc. Does anyone have suggestion for best paint?

  2. #2
    Join Date
    Jun 2011
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    Default Re: Exterior steel door

    When you say the door "is still in original white", do you mean that the white coating is the factory primer and the door has never been painted?

    Or did the door come painted white from the factory?

    If that's still the original factory applied primer on the door, then you don't need to do anything other than paint. Primer doesn't get less rough with age.

    In my view, oil based paints are superior to latex paints, but they do chaulk more than latex paints. Do you live in a southerly latitude with sufficient intense sunlight to cause paints outdoors to "chaulk"? Where are you located?

  3. #3
    Join Date
    Jul 2011
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    Smile Re: Exterior steel door

    Thanks for your reply - I live in Canada, north about 2 hour drive from Messina, New York.

    The door is white as from the factory. I have found the color I want to paint and am anxious to be started.

    Thanks again

  4. #4
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    Jun 2011
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    208

    Default Re: Exterior steel door

    OK, where you live chaulking of an oil based paint won't be much of a concern. You're at about the same latitude as me, and we rarely get paint chaulking here.

    I'm gonna presume "white as from the factory" means a factory applied primer.

    I'm gonna recommend that you talk to some of your local paint stores and find out if mold growing on paint outdoors is a problem in your area cuz that's something I don't have a feel for. I don't know how humid it is in your area. But, if the paint store people say that mold really isn't a concern, I'm prolly gonna ruffle some feathers in here and recommend you use a FLAT INTERIOR alkyd paint on your door.

    The primary difference between interior and exterior latex paints is that exterior latex paints will have mildewcides and UV blockers added to them. Exterior latex paints will always be made of plexiglas cuz paint made of white wood glue will crack and peel if subjected to moisture and high humidity for a long period of time and that can happen outside, but primary difference between interior and exterior latex paints is the additional additives in exterior latex paints to protect against mold growth and UV degradation.

    With oil based paint, the primary difference is in how hard a film interior alkyd paints form compared to exterior alkyd paints. Exterior alkyd paints form a much softer film so that they can stretch and shrink with wood outdoors. Wood is a natural material and swells and shrinks with changes in it's moisture content caused by seasonal changes in temperature and humidity. Interior alkyd paints dry to too hard a film that simply doesn't have the elasticity to stretch and shrink with the wood. So, exterior alkyd paints are made out of something called "long oil resins" which simply don't crosslink as densely and therefore don't cure to as hard and brittle a film as interior alkyd paints.

    BUT, in this case, the door is made of metal, and the thermal expansion of metal is negligible compared to the swelling and shrinking of wood outdoors. So, even an interior alkyd paint will provide sufficient elasticity to allow for thermal expansion and contraction of the door from season to season, AND by using an interior alkyd paint, you get a much harder and more durable film than if you'd used an exterior alkyd paint.

    I'm confident you don't need the UV blockers that you'd get in an exterior alkyd paint where you live, but I'm not sure how badly you'd need the additional mildewcides you'd only get in an exterior alkyd paint. In my opinion, the benefit of the harder film (and therefore better durability) is of considerable importance, and you can always clean any mildew growth off the door with a dilute solution of bleach in water. That's why I suggested talking to the paint stores in your area and finding out whether people who've painted outdoors with interior alkyd paints have had mold growing on their paint.

    What I am concerned about though, is that many paint companies will use less colourfast red and yellow pigments in their interior paints, and since I'm suggesting you use an interior alkyd paint outdoors, it'd be best to either stay away from red and yellow hues in your colour choice, or use red oxide and yellow oxide for any red or yellow called for in the tint formula. Red oxide is reddish brown in colour and yellow oxide is mustard yellow in colour, and every paint company I know of will use both red oxide and yellow oxide in the paint tinting colourants. (But, if getting the right colour is more important to you than having greater durability, you can always simplify the colour choice by going to an exterior alkyd paint instead which will use more colourfast blood red and canary yellow pigments.)

    And, contentious as this issue is, I'd opt for a flat alkyd paint for your door. Any company's interior alkyd paint will dry to a much harder and durable film (and therefore stand up better to wear and tear) than any company's latex paint, so who makes the alkyd paint doesn't really matter. By opting for a flat alkyd paint, you save yourself having to scuff sand the door to get better paint adhesion in the future when the time comes to repaint the door.

    Now, if your door already has a factory applied primer on it, you really don't need to prime over that primer or to sand it down. I'd clean the door with a Magic Eraser to get as much dirt off of it as you can and allow time for it to dry before starting to paint. If there's any oil or grease on it, I'd remove those with mineral spirits rather than detergents (like Simple Green) because mineral spirits will evaporate completely without leaving any residue.

    Ideally, if you can take the door of it's hinges and paint it in a horizontal orientation, that will allow you to thin your paint with mineral spirits and get better self leveling of your paint so as to prevent brush strokes. However, if you need to paint your door in place for security reasons, then thin your alkyd paint with a product called "Penetrol" made by the Flood Company and available at every paint store. Penetrol is really nothing more than heavier petroleum distillates that slow the drying time of the paint (just as thinning with mineral spirits does), but because the petroleum distillates in Penetrol are heavier and more viscous, you don't reduce the viscosity of the paint as much by thinning with Penetrol, and that helps to prevent the paint from sagging as it dries on vertical surfaces.

    I would paint with a brush only those areas you can't paint with a small roller. My experience has been that if you can't spray paint the door, then a roller is gonna give you a smoother finish than a brush, and on a door you only need a small 3 inch roller. (various kinds are available, but I find that the rollers with a foam rubber pile tend to leave bubbles in the paint)

    If you can tell me what colour you have in mind for your door, I may be able to offer up some additional advice and information there as well. The colour of the paint you choose determines the pigments that are put in it, and not all pigments are equal. Some pigments hide better than others, and some fade less than others when exposed to UV light from the Sun.
    Last edited by Nestor; 07-13-2011 at 12:36 AM.

  5. #5
    Join Date
    Jan 2010
    Location
    Northern Virginia
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    1,134

    Default Re: Exterior steel door

    The expansion/contraction cycle of wood doors is seasonal. For metal doors it's daily. Metal doors also will develop higher surface temps than wood. For these reasons, I think the metal door demands more of a paint.
    I'm yet to see any "waterborne" paint that would satisfy me on an exterior entry door, where I want to make a good impression.
    The very best front door paint that I have seen in person if "Hollandlac Brilliant" (type) from Fine Paints of Europe. It has the qualities I look for in a high gloss enamel. And it's suitable for outdoors. It's a true varnish-based enamel.
    Casey
    Remove not the ancient landmark, which your fathers have set.

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