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SPISurfer 12-08-2009 07:45 AM

Painting Furniture
 
I have a dresser that I sanded. I painted flat black latex enamel yesterday.

The problem is the part where I did not sand down to the bare wood. The paint has not dried and there are streaks and color variations.

I need to strip it and redo. I'm guessing the varnish was oil based.

Nestor I read a thread about stripper for oil based and latex. Can I just use the stripper for oil base? Will it remove the latex enamel as well?

I thought a quick sanding was all I needed, since the color was black. Guess I should use primer too.

Any advice is appreciated.

Nestor_Kelebay 12-08-2009 02:37 PM

Quote:

Originally Posted by SPISurfer (Post 37541)
I have a dresser that I sanded. I painted flat black latex enamel yesterday.

Furniture needs a hard, durable coating. You slide pictures and such across the top of your dresser, and latex paint simply isn't hard enough to provide good service on a working surface like the top of a dresser. I'd have used a glossier oil based paint. Even an alkyd wall paint will provide much better service than a latex wall paint on a working surface.


Quote:

The problem is the part where I did not sand down to the bare wood. The paint has not dried and there are streaks and color variations.
Can't say I know what's causing the colour variation (other than brush strokes in the latex paint. Typically, latex paint should be dry to the touch in an hour or two, but it'll still be soft. Allow 2 or 3 days for latex paint to finish forming a film. If you can smell a "freshly painted smell" in the room, that's the coalescing solvent evaporating from the paint, indicating film formation is nearing completion.

Quote:

I'm guessing the varnish was oil based.
All true "varnishes" are oil based. Years ago, when people used linseed oil based paint, they dissolved natural plant resins (called "copals") into the linseed oil to make it dry to a harder and more durable film. To make real varnish, you simply dissolve more copals of higher quality (ones that don't affect the colour of the varnish as much but still impart high hardness) in the linseed oil (or Tung oil) and leave out the pigments. So, the chemistry of real varnish and oil based paints are almost identical. The binders are almost the same. (In fact, it's almost certain that the first "enamel" paints were made by simply tinting a can of varnish in the paint tinting machine to give the varnish both colour and opacity.

Bayer (the Aspirin people) patented the very first urethane modified alkyd in 1956. So, if the furniture was made prior to 1956, it's a safe bet to presume the wood was finished with real varnish. After 1956, urethane modified alkyd resins (which we call "polyurethane") quickly became the clear coat of choice over wood because of the harder film, shorter drying time, lower cost, and higher transparency of polyurethane over varnish.

Quote:

Nestor I read a thread about stripper for oil based and latex. Can I just use the stripper for oil base? Will it remove the latex enamel as well?
Yes, there are only a small handful of chemicals that will remove paint, and those that work for oil based paint also strip latex paints. "Citrus" based paint strippers use a chemical called d-Limonene as the active ingredient, and it's a by-product of the Florida Orange Juice industry. It's a solvent found naturally in orange peels. D-Limonene will soften latex paints, but it's a waste of time on oil based paints. It strips latex paints, but not oil based paints. 3M makes a paint stripper called "Safest Stripper" that works well on both oil based and latex paints. You can have Safest Stripper on your hands all day long and it won't irritate your skin, but it still works well as a paint stripper. If I recall correctly, Safest Stripper uses a chemical called "dimethyl adipate" as the active ingredient in the product. However, any paint stripper that says that it contains "Methylene Chloride" will be the most aggressive at removing both kinds of paint. You need to wear gloves when using methylene chloride based paint strippers like Polystrippa, and it's a good idea to wear eye protection as well. You don't want to get any paint stripper in your eye, but I'd much rather get either of the other two chemicals in my eye than methylene chloride.

Quote:

I thought a quick sanding was all I needed, since the color was black. Guess I should use primer too.
If it wuz me, I'd use an INTERIOR ALKYD primer and an INTERIOR ALKYD paint on your dresser. And, I'd thin both the primer and paint with a product called "Penetrol" made by the Flood Company. Penetrol is basically a viscous solvent. It allows you to thin the paint to increase it's drying time without lowering it's viscosity. The result is that you can paint vertical surfaces without the paint "sagging" on that vertical surface as it dries. (Just don't put on too thick a coat cuz too thick a coat of anything will sag as it dries.)

PS:
There really is no such thing as a "latex enamel". The first enamel paints were made by tinting a can of varnish in the paint tinting machine. Years ago, varnish only came in semi-gloss and gloss. And, because it contained more copals than paint did, it dried to a harder and more protective film. So, the term "enamel" came to mean a paint that dried to a hard and smoother film than you'd normally expect.

So, some companies have taken to calling EVERY can of paint they make an "enamel", except for their dead flat latex paints. The idea here is that if people think that "enamel" paints are better, by just calling your paint an "enamel", then people will think it's better than the next guy's paint. When you see that word on a can of paint, the meaning of the word changes slightly to "Hey you! Yeah, you! Buy me." That is, the word "enamel" on a can of paint nowadays makes exactly as much difference as a racing stripe does on a car.

Since 1956, polyurethanes have replaced varnish as the clear coat of choice over wood. So, to make a true "enamel" nowadays, you'd tint a can of hardwood floor polyurethane or polyurethane "varnish" in a paint tinting machine, just like you would a "deep" or "accent" tint base for paint. The result, of course, would be a paint that dries to a harder and smoother film than you'd normally expect from a paint. And, such paints are sold nowadays as polyurethane based floor paints.

But, you can have fun with the guy in the orange apron with enamel paints. Ask him how you can tell it's really an "enamel" and not just an ordinary paint. (If he tells you anything other than "It is ordinary paint. That word enamel don't mean squat." then he doesn't know what he's talking about. (Cuz it really is just ordinary paint.) Ask if you can return it if it turns out to be just ordinary paint, and not really an "enamel". Cuz then you can compare it to any company's "paint" and your "enamel" won't dry any harder or smoother than any other company's "paint".

Most people working in paint stores haven't got a clue what an "enamel" paint is.

ladykaya 12-27-2009 10:44 PM

In painting furniture you should put first varnish for it so to avoid scratches before you apply paint and the best color for furniture are dark brown.


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