Patrick, you had commented "clear silicone" for sealing leaks
Although hardware store "clear silicone" is commonly used for RV leak
repair there are a couple of things wrong with use of this material for
leak repairs on our GMC's.
With the exception of very small localized application for temporary
repairs, I rarely use clear caulking since it never stays clear. During
application clear silicone gives the impression that it will remain
invisible inviting a spread of caulking beyond where it will do any good.=
Since silicone is so good at picking up dust and dirt it immediately star=
ts
to change color to match the soil color of the countryside it resides in
making it much more obvious than it began (unless of course the appropria=
te
color match was dirt).
Choosing the best solid color caulking helps maintain self control during=
the tooling of the caulking, increases the likelyhood of masking to preve=
nt
the spread of the uglyness and increases the likelyhood of cleanup prior =
to
serious cure.
Further since the formulas used to create silicones are so variable one
should be careful and pick the appropriate formula for the job. As one
example, one thing I never do is to use an acid cure (vinegar smell)
caulking anywhere near steel. The acid cure silicones can be identified b=
y
the warning on the tube of the strong smell during cure. When used on ste=
el
acid cure silicones promote rust. While I recognize that the upper cab
window and window area is primarily aluminum and fibreglass there are
fasteners in that area that may in some cases be some sort of coated stee=
l.
Another example is the use of silicone to seal between the windshield
gaskets and the body. If the leak is caused for example by water coming =
in
through the cavity between the windshield gasket and the body silicone
might stop the water entry by filling the gap. In this case a black
neutral cure silicone may be O.K. If properly applied and tooled. If
properly tooled with a soapy water solution (palmolive is good) dirt
imbedment during cure can be reduced. Since silicone and the EPDM that th=
e
gaskets are made of are incompatible the silicone will never stick to the=
gasket but it will sure stick good to the body so best get it off the pai=
nt
before it cures too completely.
I will never forget the months it took me to clean and replace the clear
silicone the previous owner used on my old SOB, but it sure looked/worked=
better once the fix was complete.
Regards
Gary Zingle
1973 GMC 26 foot
Although hardware store "clear silicone" is commonly used for RV leak
repair there are a couple of things wrong with use of this material for
leak repairs on our GMC's.
With the exception of very small localized application for temporary
repairs, I rarely use clear caulking since it never stays clear. During
application clear silicone gives the impression that it will remain
invisible inviting a spread of caulking beyond where it will do any good.=
Since silicone is so good at picking up dust and dirt it immediately star=
ts
to change color to match the soil color of the countryside it resides in
making it much more obvious than it began (unless of course the appropria=
te
color match was dirt).
Choosing the best solid color caulking helps maintain self control during=
the tooling of the caulking, increases the likelyhood of masking to preve=
nt
the spread of the uglyness and increases the likelyhood of cleanup prior =
to
serious cure.
Further since the formulas used to create silicones are so variable one
should be careful and pick the appropriate formula for the job. As one
example, one thing I never do is to use an acid cure (vinegar smell)
caulking anywhere near steel. The acid cure silicones can be identified b=
y
the warning on the tube of the strong smell during cure. When used on ste=
el
acid cure silicones promote rust. While I recognize that the upper cab
window and window area is primarily aluminum and fibreglass there are
fasteners in that area that may in some cases be some sort of coated stee=
l.
Another example is the use of silicone to seal between the windshield
gaskets and the body. If the leak is caused for example by water coming =
in
through the cavity between the windshield gasket and the body silicone
might stop the water entry by filling the gap. In this case a black
neutral cure silicone may be O.K. If properly applied and tooled. If
properly tooled with a soapy water solution (palmolive is good) dirt
imbedment during cure can be reduced. Since silicone and the EPDM that th=
e
gaskets are made of are incompatible the silicone will never stick to the=
gasket but it will sure stick good to the body so best get it off the pai=
nt
before it cures too completely.
I will never forget the months it took me to clean and replace the clear
silicone the previous owner used on my old SOB, but it sure looked/worked=
better once the fix was complete.
Regards
Gary Zingle
1973 GMC 26 foot
