[WWI] Liquid Cement Questions

Robert Laskodi wwi@wwi-models.org
Mon Dec 1 14:56:00 2003


<<<I notice that the seam appears to form a small crevice that needs
filling.
Is this simply normal or am I not applying enough cement?>>>
This is normal and is caused by capillary action in the join area. Picture
it as a "trough" and the liquid cement will creep up the sides of the trough
like a "V". DO NOT add additional liquid cement as it won't "fill the V" and
only take longer for the joint to cure.
<<<Is it necessary to clamp the pieces forming the seam together, or will
pressing together with finger pressure for a minute or three be
sufficient?>>>
A way to help fill the crevice is to apply the liquid cement, wait about 30
seconds, then squeeze the join area together to "ooze" the melted plastic
into the join. You can use finger pressure for a few minutes or clamps.
Typically, I don't use clamps all that often unless the join is really bad. 
<<<How long to wait before filling.?>>>
I let the join area "cure" for at least 24 hours (more is better) and then
sand it smooth. I try to avoid using any filler because since it is
typically solvent based it will cause a further round of shrinkage along the
join. The join will always shrink, so just before painting I touch up all
joins with additional fine sanding. Typically at least two weeks have passed
from the time I originally joined the pieces until the model is ready for
painting so the join has a lot of time to cure. If at that time the results
need filler, I use Mr Surfacer, wait 24 hours (more is better), and then
sand smooth.
HTH & YMMV
---------Bob