Originally Posted by NoExperience
I have a bathroom with kitchen/bath semigloss (not sure if its enamel)
it has a very durable surface which is what I want in the garage.
My question would be: How can you really be sure that it's an enamel inside the can and not just ordinary latex paint? And, the answer is, if it's not a polyurethane floor paint, then it's not truly an enamel. Read on...
The very first "enamel" was almost certainly made by tinting a can of varnish in the paint tinting machine. Back then, house paints only came in the oil based variety and both paint and varnish was made by dissolving certain plant resins, called "copals" in drying oils like linseed oil and Tung oil. The copals made the film harder and stronger, and the more copal you added, the harder and stronger the
film you got. The copals that increase the hardness the most while imparting the least colour were used in varnishes instead of paint, and varnishes would normally have more copals in them so that the varnish was more viscous than paint and dried to a much harder film than paint.
Also, back then, varnishes only came in gloss and semi-gloss.
So, if you tinted a can of varnish, you got a gloss or semi-gloss paint that would dry to a harder film than a normal paint would. That is, you got a paint that dried to a harder and smoother film than you'd otherwise expect from a paint.
Today, paints and varnishes have all changed, but the meaning of the word "enamel" hasn't. It still means a paint that will dry to a harder and smoother film than you'd otherwise expect.
The problem is that unscrupulous paint manufacturers have come to slapping that word "enamel" on every can of paint they make except for their dead flat latexes (which are the softest roughest paints you can buy, short of making your own milk paint or egg tempura paint).
The way they can get away with that in front of consumer advocacy agencies is because improvements in paint binders and rheology modifiers mean that paints sold today dry to harder and smoother films than the very same paint did 5 or 10 years ago. So, by that measure, EVERY paint is an "enamel" compared to what it used to be.
So, some paint manufacturers try to convince the public to buy their paint by calling every paint they make an "enamel" instead of a "paint". Behr, for instance, doesn't make a latex floor paint; they make a Porch and Floor Enamel. Behr doesn't make an interior eggshell wall paint; they make an Interior Eggshell Enamel. Get the picture? Your average uninformed consumer is going to think he's getting a better deal by buying the Behr Eggshell Enamel for $20 per gallon than the Sherwin Williams interior eggshell paint for $20 per gallon. After all, it's an enamel, it's not just ordinary paint, right?
Basically, you need to understand that there are very many different kinds of latex paint binder resins used to make latex paints, and a good measure of the quality of a latex paint binder is how hard a film it forms. The harder the film, the better it will stand up on working surfaces, like floors, shelves and table tops. Also, the harder and stronger the film, the harder extender pigments you can put in it to provide for better "scrubbability" in the paint (which is how much you need to scrub a paint before you scrub it off the wall). The higher the scrubbability, the more you can scrub the paint before you'll scrub it off, OR dull it's gloss trying to scrub off a stuborn mark. So, you can make better latex paint if you have a binder that forms a harder film.
It's very possible that the latex paints you were most satisfied with were more expensive paints that used a better quality binder resin, and you presumed it was because they were "enamels".
Also, there are different waterborne paint chemistries. You can buy water thinned paints that form much harder films than either latex or alkyd paints, like General Paint's Envirogard:
(and even though General Paint acknowledges that it's an acrylic binder, I don't otherwise have any clue about it's chemistry or how it forms a film.)
But, be wary of that word "enamel". Since polyurethane has replaced varnish as the clear coat of choice over wood, nowadays an enamel would be a polyurethane floor paint. If you see a paint manufacturer calling every paint he makes an "enamel", EVEN HIS LATEX PAINTS, then the meaning of the word changes to "Hey you, yeah you. Buy me!". It has about as much affect on the paint's performance as a racing stripe does on a car's performance. It's put on the can like a racing stripe to try to convince the uninformed consumer that the paint is inherantly better than one that doesn't call itself an "enamel".
You can have some fun with this. Pretend to be a skeptical consumer and demanding proof from the guy in the orange apron that the paint in the Behr can really is an enamel and not just an ordinary latex paint. Almost certainly the guy in the orange apron won't know what an "enamel" is either.