Murray wrote:
> This was the use of contact cement as a sealant rather than an adhesive.
> Screws and seams on this product (I am not at liberty to explain what
> indistry of product) are sealed with a contact cement (some mil-spec
stuff),
> then when it dries, it is painted over with either a lacquer-based r
> epoxy-based paint.
Hi Murray,
Surprisingly I have just been in the process of experimenting with
using contact cement as a base in a coating mix . What I have done is as
follows:
I mix a professional "Upholsterers contact cement " which is a
thin red liquid about the consistency of cream ( much thinner than regular
contact cement ) and is safe for foam, vinyl , rubber ect ( hopefully it
will not lift or dissolve the existing coating on the bellows)..... It
is then mixed with a rubber roofing compound called "Roof Caulk" used for
repairing rubber membrane roofs..... The roof caulk is rather thick dense
black rubber like material and almost like tooth paste. The contact
cement thins it nicely to the consistency of honey. The problem at this
point is that it is not quite dense enough when mixed and it dries a
little tacky and is not very tough when scraped . It seems not to
thoroughly dry and pulls away from a test on a piece of glass when scraped
after a day or so of drying... ... It forms a membrane though and pulls off
as if it wanted to come off in a thin rubber sheet. But the membrane is weak
and breaks .. It is almost like it is not thoroughly dry...... The density
also is not quite where you would want it to be in this thinned mixture.
This mix at this point is the consistency of thick paint.
I then mixed in a little "Black Out " that is a very dense black
paint used by Neon Sign men to black out the electrodes or any part that
they do not want light to go thru on their neon tubes . It is very
durable, very opaque as it will hold up for years to outdoor weather
attached to the glass tubes . The Black Out is the consistency of paint.
.. The problem with using it strait is that it is not very flexible and
cracks and flakes when bent which is also the effect on the neon signs over
a few years time.. When mixed with the contact cement and rubber roofing
compound it seems to have the effect of a drying agent.
The mixture of the three items so far is remarkable!. It adheres to
the glass test piece very aggressively. It looses its tackiness and dries
but still has remained rubbery... It is very opaque at about a 2 to
3 mil coating ( a little thicker that scotch tape) . It remains flexible
although I have only let it dry for a few days. I coated some paper towels
with it and it covers nicely and bends nicely ...It does not stick to itself
when folded over after drying..... I may just give this mix a try after a
little more testing.
I will paint some cellophane with it, let it thoroughly dry and put
it thru a bending test and put it in contact with itself over time to see if
it will eventually stick to itself..( something you would not want with
bellows. )
John Cremati
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