Long term discoloration from adhesives

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   Years ago I'd read somewhere about using spray adhesive to hold a patch down and in place prior to sewing over it while repairing a sail but I think there was a warning that eventually the adhesive would darken and be visible.  Is this true?  

The other day I restitched an old sailrite kit sailcover that was well done but tired.  I noticed there was a perfectly straight dark line about 3/8" right in the middle of the hem which I'm guessing is the adhesive from the old seamstick tape.  Is it normal for this to become visible after several years?  I've not seen it like that before on other projects but it immediately brought to mind the warning I'd read about the spray adhesive.  The sailcover is old enough that the color on the inside out of the sun is now very different from the color on the exposed side.  In fact it's the most color change I've ever seen in sunbrella from sunlight but I think we're a little closer to the sun here on the Texas coast.  It certainly feels that way.

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cbys Members Profile Send Private Message Find Members Posts Add to Buddy List Forum Member Joined: 05 September 2011 Location: Corpus Christi Status: Offline Points: 12	Post Options Post Reply Quote cbys Report Post Thanks(0) Quote Reply Topic: Long term discoloration from adhesives Posted: 05 September 2011 at 10:23am
	Years ago I'd read somewhere about using spray adhesive to hold a patch down and in place prior to sewing over it while repairing a sail but I think there was a warning that eventually the adhesive would darken and be visible. Is this true? The other day I restitched an old sailrite kit sailcover that was well done but tired. I noticed there was a perfectly straight dark line about 3/8" right in the middle of the hem which I'm guessing is the adhesive from the old seamstick tape. Is it normal for this to become visible after several years? I've not seen it like that before on other projects but it immediately brought to mind the warning I'd read about the spray adhesive. The sailcover is old enough that the color on the inside out of the sun is now very different from the color on the exposed side. In fact it's the most color change I've ever seen in sunbrella from sunlight but I think we're a little closer to the sun here on the Texas coast. It certainly feels that way.

MattGrant Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Sailrite Employee - Expert Joined: 21 April 2005 Location: United States Status: Offline Points: 3012	Post Options Post Reply Quote MattGrant Report Post Thanks(0) Quote Reply Posted: 05 September 2011 at 9:02pm
	Everything fades in time but Sunbrella comes as close as you can get to fade-proof fabric for harsh outdoor environments. Rubber based adhesives or hybrids can certainly yellow over time. The best "non-yellowing" products are acrylic adhesives. The negative to acrylic is that its initial sticking power is not as good as the rubber based type. Dark colors hardly ever show the yellow but natural and linens can after years of sun exposure. Hope this helps. Thanks, Matt Grant Sailrite
	Best Regards, Matt Grant Sailrite

Sue2 Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 12 April 2010 Status: Offline Points: 164	Post Options Post Reply Quote Sue2 Report Post Thanks(0) Quote Reply Posted: 19 February 2012 at 9:17am
	For what it's worth, we recently bought a used older (white dacron) sail. The sail is generally still in very good condition, but you can clearly see the yellowish lines of seam-stick tape that were used in construction. However, given that this sail is at least 30 years old, and I have not noticed the issue on newer sails, I would call that a respectable performance for the tape, and, given the benefits of the tape, I will continue to use it!