[WWI] Modeling 101 doubt - Micro Sol and Future

[Mark Shannon]

It really isn't a problem.  If you see the whitening appear, just do not
touch anything.  The whitish fogginess will go away as everything dries.  A
later coating to seal the decals will help, too.

Ways to avoid it in the first place are:

Let the Future coat dry at least 12, preferably 24 hours,
Use the minimum amounts of MicroSol in any one application, and
Use the thinnest coats of Future necessary to get a gloss coat.

What happens is that all acrylic and enamel paints and coatings have two
drying times.  I'm not sure if it is a general term, but in the automotive
paint industry the first is called the "tack-free time," and you often hear
'touch dry'.  This is the point at which you could place a cotton wool ball
on the painted surface and pull it back off without leaving any strands
behind (the test is to actually do this on a painted test sheet every five
minutes until you leave no lint behind)  However, if you were to put some
solvent on it it would dissolve and get mushy, or if you press on the paint
at this stage, you would leave a fingerprint.

There is a final drying time, which is really a 'curing' time.  What is
happening is that the shorter chains of the film producing chemical
(acrylics, linseed, alkyd, or whatever) are fusing together into a polymer
that will form the final coat.  With many hobby paints, there is an
intermediate time when you can safely mask over the paint, even though it
is not fully cured.  Future is like this -- since it was designed as a
floor 'finish' it has a relatively short time before it won't lift up or
take a fingerprint, but it really takes longer to cure -- sort of fully
cured in about 48-60 hours, like the PollyScale paints.  In floor use, you
can walk on it in thirty minutes, but it is designed to only slowly
polymerize so that it is easy to strip for re-'finishing'.  If you check,
you will see that Future gets glossier over about the first week.

So, letting it have a longer 'drying' time makes it more durable.  Shorter
times mean that it is still not cured and will dissolve or soften with a
mild solvent like MicroSol, but as the Sol evaporates out of the film it
will leave not residue and no permanent damage -- unless you touch it or
press or scrape during the time it was soft.

Lacquer paints have a different drying chemistry, but they still have a
'tack-free time' and a fully cured.

Mark Shannon
shingend at ix.netcom.com



> [Original Message]
> From: Marcio Antonio Campos <marcio.antonio.campos at gmail.com>
> To: World War I Modeling Mailing List <wwi at wwi-models.org>
> Date: 6/4/2008 6:35:57 PM
> Subject: Re: [WWI] Modeling 101 doubt - Micro Sol and Future
>
> 2008/6/4 Rob Stewart <rob at rob-stewart.to>:
> >
> > Hi,
> > I have had no problems with that.
> > What happens?
>
> It gets whitish around the decal. The best comparison I can imagine is
> a glass after a long time in the freezer.
>
> All the best from Brazil
>
> Marcio