I really like the idea of having a wider selection of colors and also a (cheaper) fabric that I'm not too worried about ruining as I delve into sewing/gear-making for the first time.
i thought it made a nice fabric, it was different feeling than sil, but not in any bad way, looked a little different too, almost a little more translucent with the grey i used
Scored! Found some camo 1.1 oz ripstop in the dollar bin! But… only 5 yards. I was hoping to make an 8x8 tarp, guess it will have to be a 7.5 x 8 (or nine). Interesting, it’s 68” wide.
Cut it in half. All numbers from here on are for one half… Also, all measurements were by hand with a cheap scale, so factor in some margin of error.
7.5 feet x 5.67 feet = ~ 4.7 sq yards. 4.9 ounces. 4.9 / 4.7 =~ 1.03 oz / sq yard.
Commercial Sil is advertised as 1.3 oz / sq yards.
Therefore, to make 4.7 sq yards @ 1.03 oz / sq yard = 1.3 oz/sq yd, you need to add ~ 1.4 ounces of silicone.
Using a 3:1 ratio of mix to silicone by weight … 9 ounces of mineral spirits ~ 16 fluid ounce plastic cup. On wax paper, 3 ounces by weight of silicone (100% sil caulk in a tube) ~ a mound about the size of a baseball cut in half. (I over estimated the amount of waste. My final product is actually close to 1.5 oz/sq yard, ie very little loss.) Dump it all in a 5 quart plastic paint bucket. $6.99 electric hand mixer from Wally’s (cake mixer/egg beater) … Beat it for about 10 minutes… (First time was for 5 minutes. This wasn’t long enough. Small globs of sil all over.)
Have some paper towels ready…. Also, I used 4 safety pins and some Masons’ line tied high across 2 support poles in my basement. Put newspaper under the Masons’ line. Have all this ready before the next step.
Shove the fabric in the bucket... bare handed. Push, pull, squeeze, massage, knead, pull it part way out, re-drape into the bucket, push, pull, squeeze it like a sponge, pull it part way out, re-drape… do this for 5 – 10 minutes. Hope sil does not cause cancer! (Used latex gloves once, but they fell apart in the mineral spirits.)
Wipe your hands. Put safety pin in one corner and hang on the line. Put safety pin in other corner on the edge, hang. Put safety pins in the middle and hang. Use extra line to the posts to pull the ends tight. Straighten the hanging wet fabric to get all folds out. Wipe hands again. Pour fresh spirits on paper towel and wipe hands again. Wash hands with soap and hot water. Wash again.
Let it dry overnight. Take it down and test.
I actually postponed the test until after finishing the tarp. Final dimensions are 9+' x 7+'. With grosgrain tieouts and a new, smaller, batch of the mix for seam sealer ~13 ounces. Good test too, put it up in the yard to do the seam sealing and storms came through 2 afternoons in a row. No leaks!
Note: No brushes or squeezeeges required for the basics. Used an old toothbrush to apply seam sealer.
you didn't wipe off the excess with anything? i wiped mine as dry as possible with a cloth.
glad it turned out well, i think you are the first to make an actual piece of gear using this method.
Forgive the change in directions, but while I have the attention of fabric-minded folks, maybe someone can help. I have an older backpack that spent too many years in my attic. The fabric (Cordura?) has become gummy feeling on the inside. Any cures? Suggestions?
Sometimes even a Blind Hog finds an Acorn
...the first piece, where I only mixed the solution for 5 minutes, did have lots of small flakes of silicone after it dried. No problem to pick them off, if the looks bother you and you want to waste the time. 2nd piece where I mixed for 10 minutes did not have this issue.
Now for the big decision... is 7'2" wide enough????