Sikaflex 295 versus Dow Corning 795

Dan_Y

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Oct 13, 2008
514
Hunter 36 Hampton
CD - you're giving me nightmares of putting up a kitchen backslash... ugh... haha. I used the spoon to trowel the 795 around on the mating surfaces and probably the first pass across the joint, but may have finished the way you point out. I can't recall now. Years ago a builder said he used a finger dipped in bowl of dish soap on exterior house caulk when smoothing wider beads. Works well, but did not want to try it on 795 for fear of inhibiting the surface cure (see below).
As a note of caution, real or not, the yard used either denatured alcohol, acetone, or some other solvent to smooth the sikaflex 295uv joint when first rebedding my dead lights. Supposedly, use of the wrong solvent is what stopped the surface cure of the sika according to the sika rep. It never set up outside, but set up fine inside where it was not wiped with solvent. After two more tries by the yard with the same result (the 3rd time w/o primer), I did it myself with the 795.
 

IAMCCF

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Jun 29, 2015
33
ODay 28 Quincy Yacht Club
Hi Dave,

I will be replacing all my ports on my Oday 28. Can you send me those instructions?

Thanks,
Chris
 

Vegas

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Feb 12, 2009
137
Beneteau 37 JBM, St. Clair Shores, MI
I have been toying with the idea of using 3M VHB tape just to get the initial bond and hold the widow in place which also acts as the shim to prevent excessive squeeze out to the point of having too thin of a film. My window pattern overlaps the window cutout by 1.25 inch, so I will use a narrow strip (3/8") of VHB tape. I'll strip the paper cover from the acrylic only off of the bonding surface and sand prep that surface, wipe with tack cloth and alcohol prep to clean.... then brush on a thin application of thinned 795. I believe this is a better substitute for black paint and prevents seeing the VHB tape through the acrylic after install. After that brushed on coating cures (24 hours or maybe a little more) I'll put on the VBH tape and mount the windows, using a wooden roller to firmly press them. I forgot to mention the mounting surface around the window cut-outs will be sand paper preped and cleaned with alcohol as well. With the windows firmly in place with VHB tape I'll 'caulk' in the 795 around the perimeter of the window, filling the gap but without too much squeeze out.
I think this way I'll have a consistent film thickness, less risk of the windows displacing during install, and not having clamps that could be too much pressure and squeeze out too much sealant. I will also add a similar bead on the inside of the windows. Does this sound reasonable?
CloudDiver, This is my current thought on how to re-bed my portlights. Did it work for you?