> Ok, I don't understand the problem with painting
bricks, but it seems they
> exist. Even TT is nervous about painting them.
> As I understand it, there are two problems. First,
anything but a
> water-based basecoat will cause the acrylic to
deteriorate and the crackle
> effect begins.
====
For sure, any chemical solvent that is the
similar/same as the acrylic's base will destroy it
over time.
TT ought to know, but FWIW, a number of Bricklins and
DeLoreans were painted by a local dealer back in the
early 80's to 'enhance' his ability to sell them at
inflated prices. He used IMROM (a polyurethane) with
an elastomeric additive, and for years after thay
still looked like new to me. They've all since
disappeared from the area, so I don't know about
really long term effects though.
FWIW, during the time my car was a driver, I used
fast evaporating lacquer thinner or 3M Adhesive
Remover to 'deep' clean my white panels. So far, no
cracks/surface'hazing' or other obvious deterioration
has occurred.
This implies to me that spraying many thin coats of
acrylic lacquer with a finishing thinner in a >85deg
booth would work. This was the standard for custom
finishes until EPA regulated it to the point of
commercial extinction.
I repainted my RX7 ~8 yrs ago this way, and folks
still ask me who just repainted it.
Still, a two part urethane, and possibly a clearcoat
seems the way to go for best durability.
====
Second, there is a claim of the body panels
flexing, causing
> the paint to crack and separate from the acrylic.
>
> Now the first one I understand, but after owning a
fiero with extremely
> flexible "enduraflex" panels that actually flex
under finger pressure, with
> absolutely no signs of paint problems for many
years using flexible
> coatings, the second problem should not exist.
Personally, after lots of
> painting experience on many different substrate
materials and many different
> types of coatings, the type of cracking and
separation on the B cars I've
> seen appears to be very similar to problems caused
by a lack of adhesion
> between the substrate and coating used. This would
suggest that it is not
> flexing that is the problem, but adhesion,
adhesion, adhesion. I'm very
> interested in others' experiences and hypotheses.
====
'Cracking' paint is usually caused by too good an
adhesion/too 'stiff' a material on too flexible a
substrate. Blisters are examples of poor adhesion.
The problem remains though that the acrylic itself is
still going to crack underneath. Had Bricklin used a
flexible bonding agent to attach the acrylic to a
separate fiberglass subpanel, or where it mounts
directly to metal, cracks would only occur due to
really high velocity impacts.
If I ever get to fix mine I'm going to bond the door
skins with something flexible, as I know from
personal experience that the skin can be seriously
dented without cracking (at least when newer), and
return to normal over a period of time (dependent on
temperature/relative humidity).
Has anyone tried the systems coatings for Fiero
panels, those used to coat the flexible bumper parts,
or to refurbish bathtubs/shower inserts?
GM
> stephan #2821
>
>
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