Experience Using Sikaflex for Canopy Installation

22 Nov 2004 Experience Using Sikaflex for Canopy Installation

Gluing the tip up canopy on my 9A has been a real learning experience that I’d like to share with everyone.

Several builders have sent me questions about the procedure since a note that I posted to the List a few days ago. Guess that there are several people that would like to know more.

I highly recommend the Sikaflex 295UV. (Comes in black or white.) Black is recommended. You will need two or three 10.5 ounce tubes plus one pint of the Sika 209 Primer and one pint of the Sika 229 Cleaner. One pint of each would probably do two canopies.

On the front canopy edge I taped, cleaned, and primed about 3/4″ on the inside and the outside of Plexiglas. I also primed the edge. I set the canopy down into a bead of adhesive on the cowl. If I did it again I would position the canopy and run a bead of adhesive along the outside edge and let it set overnite. A gap of about 1/8″ between the plastic and the cowl skin is a good thing. You can use rubber garden hose washers to maintain the gap. Just be sure not to glue them in. After the adhesive sets you can pull them out and add more adhesive in their place. You can then go back later and run a bead of adhesive on the inside.

I built up a fairing about 1 1/4″ wide around the whole front edge with the Sikaflex using a curved squeegee and vinyl electrical tape as a guide. The great thing is the adhesive sands very well with 220 grit open coat paper. No fiberglass!

You can also paint the fairing for UV protection but be sure to wait until it has fully cured…about two weeks. Ask me how I know. The manufacturer recommends epoxy or polyurethane paint. Something that has some flex to it after it drys is a good idea to prevent cracking.

The only screws through the plastic canopy are in the frame sides. I used only adhesive on the canopy bow..no screws. All you see is the jet black primer showing through on the outside..Looks pretty cool!

My best advice is don’t use too much adhesive at a time. You can always go back and add more where you need it two hours or two weeks later.

After starting out with two tubes of the adhesive and doing the front, sides, and roll bar I have a little less than 1/4 tube left. I think it might be barely enough to do the rear window, but since it will be several weeks before I can install the rear window I will probably order a third tube. Once opened I’m not sure how much moisture and, therefore, setting will occur inside the tube.

The Sika 226 Cleaner is mainly isopropyl alcohol but, importantly, it also contains a bonding agent for the primer. It’s about $10.00 a pint. You wipe it on the scuffed surface of the plexi and aluminum with a lint free cloth and let it dry for 10 minutes before applying the Sika 209 Primer. The primer is about $30.00 a pint.

Apply the black primer with a soft brush..flow out a thin even coat with no voids particularly on the Plexiglas because places you miss will show through on the other side. Let the primer dry for at least 20 minutes but no more than 2 hours before applying the adhesive. You can clean the Primer from brushes with lacquer thinner.

The unset adhesive cleans up easily with paint thinner but nothing I have found will remove the cured adhesive except sanding. This adhesive is really tough stuff. It cures like very hard, tough rubber…you almost can’t pull it apart and the bond it makes to Plexiglas is incredible.

For more info go to www.sikaindustry.com Look up Marine Applications. You should find a material data sheet and an applications guide in that location.

Jim Ellis
finishing canopy RV-9A tip up