Gassing off- How long for Bondo (and other GRPs)to set?

[Gorminrider]

good idea per epoxy and it Might do for a fast "saviour" if it starts to lift too...I'm saving these pages of advice so if it comes to my Suzukis, it'll be better. ... I still don't know what caused the pimple blisters in the PO's otherwise seemingly ok paint job (and I apologize for not taking pix)...but anyways, this is what it is now. The 2K clearcoat scared me just reading the directions, so I went with spray enamels, and brushed varnish after experimenting with various coatings and paints. I am pretty happy with job I did and it Survives gas spills very well so far. and no blisters yet.

[60ratrod]

for those interested in rust and corrosion, here are a few excerpts from volume 1 of the corrosion control manuals that I use. basically all corrosion is, is metals trying to return to a baser, more original state, as they are naturally found in the earth. here are the types of corrosion that we encounter on motorcycles:

this one is what we normally see on frames, inside and outside of tanks, and on engine blocks:
UNIFORM SURFACE CORROSION. Uniform
surface corrosion is probably the most common type of
corrosion. It results from a direct chemical attack on a
metal surface that proceeds uniformly over the entire
exposed surface (see Figure 3-7). The metal gradually
becomes thinner and eventually fails. On a polished
surface, this type of corrosion is first seen as a general
dulling or etching of the surface and, if the attack is
allowed to continue, the surface becomes rough and
possibly frosted in appearance. An example is the
etching of metals by acids. The discoloration or general
dulling of metal created by exposure to elevated
temperatures is not considered to be uniform surface
corrosion. Coating/sealing the exposed surface will
protect it from this type of attack. Also, corrosive elements
may be removed through air movement and drain holes.

this is the type I warn about when using stainless fasteners in aluminum blocks:


GALVANIC CORROSION. Galvanic corrosion
occurs when different metals are in contact with each
other and an electrolyte, such as sea water. It is usually
recognizable by the presence of a buildup of corrosion
deposits at the joint between the metals. For example,
aluminum skin panels and stainless steel doublers,
riveted together in an aircraft wing, form a galvanic
couple if moisture and contamination are present.
Figure 3-8 shows galvanic corrosion of magnesium
adjacent to steel fasteners. The potential for galvanic
corrosion is greatest when the two metals are well
separated from each other in the galvanic series and are in electrical contact.


both of the above types can and will lead to this type:

INTERGRANULAR CORROSION.
Intergranular corrosion is an attack on the grain
boundaries of the metal. A highly magnified cross
section of any commercial alloy (see Figures 3-11 and
3-12) shows the granular structure of the metal. It
consists of quantities of individual grains, each having
a clearly defined boundary, which chemically differs
from the metal within the grain. Frequently the grain
boundaries are anodic (tend to corrode more easily) to
the metal within the grain. When an electrolyte is
present, rapid selective corrosion of the grain
boundaries occurs. High strength aluminum alloys,
which depend on precipitated phases of alloying
elements for strength, are particularly susceptible to
intergranular attack. Figure 3-13 shows how
intergranular corrosion progresses in 7075-T6
aluminum alloy adjacent to steel fasteners. In this
example, the grain boundaries are anodic to both the
metal grain and the steel fastener.



this is what most corrosion leads to if not addressed, but usually takes a while depending on the metals involved. best example is when you find an old sheet of steel on a car and find that it's flaking off:

EXFOLIATION CORROSION. Exfoliation (see
Figures 3-14 and 3-15) is an advanced form of
intergranular corrosion where the surface grains of a
metal are lifted up by the force of expanding corrosion
products occurring at the grain boundaries. The lifting
up or swelling is visible evidence of exfoliation corrosion.
Exfoliation occurs on extruded, rolled, wrought, and
forged high strength aluminum and magnesium parts.
This type of corrosion most often occurs on extruded
sections of metal and is found primarily in aluminum
sheet around steel fasteners. Its prevention involves
separating the aluminum and steel by a barrier, such as
zinc-chromate primer or sealant.