Alkaloid?
Logic 3:16
I know what latex paint is (quick-drying alcohol-based, can be thinned-down
and cleaned-up with water, good in damp and weather-prone areas but not very
wear-resistant) and I know what oil-based paint is (takes much longer to
dry, has a smoother harder finish and therefore best for floors and trim but
does not stick well to damp porous surfaces, is thinned-down and cleaned-up
with petroleum distillates).
But exactly what are 'alkaloid' and 'acrylic' paints? Are they just fancy
new terms for oil paint or different beasts entirely?
T.I.A.
- Logic316
Richard E. Thiess
PAINT 102
Your question is of the apples and oranges type. Latex originally referred
to the rubber "sap" that could be drained from rubber trees. Today, latex
refers to the structure of the binder in it's carrying media. The word
latex can be use interchangeably with emulsion. It is a very small drop of
resin floating in (generally) a blend of water and some coalescing aids.
These aids can be co-solvents or surfactants which help the drops to merge
into a continuous film as the water evaporates. There is a whole world of
resins which can be emulsified and used in a water-borne paint;i.e.,
acrylics, alkyds, vinyl acetates, etc.. There are also water soluble and
water reducible resin systems.
The term "oil-based paint" is sometimes used synonymously (and sometimes
incorrectly) with "solvent-based paint". True oil based paints were just
that, a mixture of pigment and some vegetable oil such as linseed oil. As
our paint chemistry improved, we discovered that we could make paint films
superior to "oils" if we cooked a poly-hydric alcohol with a di-basic acid
and then modified it with a vegetable oil. That combination we nick-named
"alkyd" from ALcohol+aCID.
Again, alkyds can be emulsified in water or solublized in solvents.
Acrylics (A true 100% acrylic contains no vegetable oil, but an acrylic
modified alkyd does.) can be emulsified in water or solublized in solvents.
So back to your original question, water-borne (let's throw latex back in
here) or solvent-borne refers to the media which assists in getting the
"goodies" from the bucket to the part being painted. Alkyd, acrylic, vinyl,
polyurethane, et. al., refer to the goodies left on the part after the
solvent or water evaporates.
Regards,
Richard
Norcross, GA USA
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