9 oz fabric and Zar. Testing update

[BobV]

I just coated the 9 oz fabric with Zar ultra exterior oil-based polyurethane and discovered that the two are not compatible.  I'm guessing that the material expanded by 5% or so, lots of wrinkles.  I should have tested it but used Zar many times on the 8 oz material with no problems.  I'd like to use a polyurethane rather than a paint.  What other brands of oil-based polyurethane have been used on the 9 oz fabric?  I like the 9 oz material, no pull holes in sewing it up.  I used the same method as with the 8 oz material that I learned from watching Jeff's videos, which are great by the way.  It shrank as good as the 8 oz, and will appear to not need as many coats to fill the weave to a smooth finish. 

[Kudzu]

Recently  had someone that used Coelan and had the same thing happen so I added a warning to that page. But the good news is a week latter they tried heating it and it shrunk back to size and pulled tight. Haven't hear any more so I assume it stayed tight. You might want to try it as you have nothing to loose.

 

But as you said, you should ALWAYS test a finish on scrap first.

[BobV]

I didn't wait a week to apply some heat.  It did shrink but didn't last long.  Do you know of any other polyurethane that will work?

[Kudzu]

Have not tried poly on it so no idea.

[BobV]

I've tested four coatings that I had in my paint cabinet from various projects.  Ace polyurethane, Minwax polyurethane, Minwax spar urethane (which I think is another term for polyurethane), and Man O' War marine spar varnish.  All the coatings worked with the 9 oz material.  I'm going to go with the Man O' War varnish, my paint store mentioned that the spar varnish will be more flexible than a interior/exterior polyurethane.  So it could be that Zar and Coelan are maybe the only two coatings not compatible with the 9 oz material.

[HBREW]

Haven't been on the post for a while but am getting ready to build another sof so I thought I would catch up. I built a shad last year shortly after the 9 oz came out and skinned with it.  It did sew on very nicely.  The few wrinkles ironed out nicely. I applied Varathane oil based sparurthane by Rust-Oleum.  I experienced similar results with this product as with the Zar, more so where i has used heat to shrink the fabric, but some on the non-heated fabric.  Reheating the fabric did not give lasting results. Anyone experiencing issues with oil based porch paints? Have not seen any mention of that.