Solvent for Gap-Seal tape prep

[AS]

Hi y'all,

I have to replace the cloth tape gap seal after loosing the one on the rudder in flight. I removed the adhesive residue with GooOff, which worked really well and washed the area with denatured alcohol. The new tape still won't stick very strong. The glider is metal with PU-paint.
What surface prep solvent can you recommend to make the tape stick?
Thanks for the any advise,

Uli
'AS'

[Tim Taylor]

Which denatured alcohol did you use? Be sure to use at least 90%. Second, mask off the area that will be taped and lightly sand with 1000 or 1500 grit wet sandpaper. Sand just enough to dull the surface.

[Tim Taylor]

Forgot to mention I also use a small roller, designed for installing pill and stick flooring, to push the tape down to insure full contact of the adhesive.

[AS]

On Sunday, August 13, 2017 at 2:01:31 PM UTC-4, Tim Taylor wrote:
> Forgot to mention I also use a small roller, designed for installing pill and stick flooring, to push the tape down to insure full contact of the adhesive.

Thanks, Tim! The Denatured Alcohol I use is the pure stuff - not Rubbing Alcohol. I will try sanding and the edge-roller.
I was wondering if Acetone would be a better choice to clean up but am not sure if it does attack PU paint.

Uli
'AS'

[Tim Taylor]

Uli,
I have found acetone will attack most paints. I use it on gel coat sparingly, but try to use less aggressive solvents if posible. I use the 95% "rubbing" alcohol for most daily wing tape clean up. Works well and and dries clean without an oily feel. Also, see I fat fingered the "peel and stick" tile.
Good luck,

Tim

[Craig Funston]

On Sunday, August 13, 2017 at 11:51:18 AM UTC-7, Tim Taylor wrote:
> Uli,
> I have found acetone will attack most paints. I use it on gel coat sparingly, but try to use less aggressive solvents if posible. I use the 95% "rubbing" alcohol for most daily wing tape clean up. Works well and and dries clean without an oily feel. Also, see I fat fingered the "peel and stick" tile.
> Good luck,
>
> Tim

3M Prep-sol. Works well and doesn't attack the paint like acetone. You do have to wipe it dry after application though.

Craig
7Q

[[email protected]]

I sand the area where the stickie will go with 200 grit and sand the inside (10mm) of the Mylar with 200 grit also. Then wipe everything down with Acetone.........it won't hurt Poly Urethane. Mask off the area to insure the Mylar goes on straight, then roll it down with lots of pressure. I use a 1" bearing on a stick.
JJ

[Eric Greenwell[_4_]]

wrote on 8/13/2017 3:37 PM:
> I sand the area where the stickie will go with 200 grit and sand the inside (10mm) of the Mylar with 200 grit also. Then wipe everything down with Acetone.........it won't hurt Poly Urethane. Mask off the area to insure the Mylar goes on straight, then roll it down with lots of pressure. I use a 1" bearing on a stick.
> JJ

Is the sanding on the Mylar to roughen, or to remove a surface treatment that
interferes with adhesion? I ask because the Mylar tapes I've bought with the
pre-applied transfer tape are not sanded underneath the transfer tape, and I don't
have any adhesion problems with them.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorgliders/publications/download-the-guide-1
- "Transponders in Sailplanes - Dec 2014a" also ADS-B, PCAS, Flarm

http://soaringsafety.org/prevention/Guide-to-transponders-in-sailplanes-2014A.pdf

[[email protected]]

I used some Mylar that came with adhesive applied and the customer returned after one wing shed its top Mylar after he took the bird near redline! That's when I decided the process needed better "tooth"! Without sanding you are asking the adhesive to hold one smooth surface to another smooth surface.. I have had no problem since I started sanding both sides with 200 grit and wiping both sides with Acetone just before application. Also, when replacing the transition tape, be sure to wipe the area with Acetone just before applying the new tape..............remember the bailout at Uvalde after the newly applied transition tape lifted and the pilot thought he was unable to maintain pitch control. The pilot had removed old transition tape, waxed the bird and then re-applied new transition tape over the wax!
JJ

[[email protected]]

If you live in a cold climate or are trying to do this in the winter, you should also use a heat gun or hair dryer to warm the surface, transfer tape and mylar as you use the roller. Don't get carried away with the heat, as you can easily damage the mylar and/or wing if you get things too toasty. Sometimes I also go back over the bond after a couple of days with the heat gun and roller. Don't melt the safety tape.

[[email protected]]

Most of the above advice concerns Mylar seals, so the real question is what solvent Uli needs to prep the surface for the cloth tape. You can try anything, but in order of aggressiveness (And possible damage to the PU paint) Methyl Ethyl Ketone is very aggressive and evaporates with little residue, acetone is second in both qualities and alcohol is the gentlest. It is also possible that the tape you are using does not have as good an adhesive as the original, or it needs a longer time to take a set. Let it cure for a while and use a roller to ensure the join is compressed as much as possible.

[AS]

On Monday, August 14, 2017 at 10:43:17 AM UTC-4, wrote:
> Most of the above advice concerns Mylar seals, so the real question is what solvent Uli needs to prep the surface for the cloth tape. You can try anything, but in order of aggressiveness (And possible damage to the PU paint) Methyl Ethyl Ketone is very aggressive and evaporates with little residue, acetone is second in both qualities and alcohol is the gentlest. It is also possible that the tape you are using does not have as good an adhesive as the original, or it needs a longer time to take a set. Let it cure for a while and use a roller to ensure the join is compressed as much as possible..

Thanks, Mark! I heard about MEK and its potency, so I will stay away from it. All good advise so far. I looked at the roll of tape which came with the glider and I just don't know how old that stuff it. The adhesive may not be as strong as it was when new. I ordered fresh TESA stuff from W&W.
In addition, I put the current tape on when it was too hot and humid to fly here - South Carolina is known for reaching Rh values of 120% ;-). So maybe that has an influence, too.
Uli
'AS'

[bumper[_4_]]

3M's website has so good info on this that parallels JJ's and other's advice. Application should be between 70 to 100F. Roller pressure about 15 psi - I use the stick handle, bearing thing but add a "tire" from a sliced bicycle inner tube or some self vulcanizing rubber tape. The tire helps even out the roller pressure.

On mylar seals, mask half and sand the other. The added tooth is critical. 3M says to use at least 50% isopropyl alcohol (I've used denatured alcohol as final clean with good results, but would assume 3M's recommendation is better than mine.)

It's important to avoid stress on seals initially (position control surfaces accordingly). Bond gets 50% strength during the first 20 minutes or so. 90% during first 24 hours.

bumper
SRS cobra ramp sliders
MKIV yaw string
Quiet Vent

[Eric Greenwell[_4_]]

wrote on 8/14/2017 6:24 AM:
> I used some Mylar that came with adhesive applied and the customer returned after one wing shed its top Mylar after he took the bird near redline! That's when I decided the process needed better "tooth"! Without sanding you are asking the adhesive to hold one smooth surface to another smooth surface.

Did you determine the transfer tape came off the Mylar and not the wing?

I don't see any inherent problem with adhesive adhering to a smooth surface, and
never had the tape come off the Mylar, but it has come off the glider. What
preparation do the transfer tape and/or Mylar manufacturers recommend?

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorgliders/publications/download-the-guide-1
- "Transponders in Sailplanes - Dec 2014a" also ADS-B, PCAS, Flarm

http://soaringsafety.org/prevention/Guide-to-transponders-in-sailplanes-2014A.pdf

[Dan Marotta]

I just had the lower surface mylars replaced on my wings. Fidel used
acetone and cleaned the surface well. No other prep. My glider has PU
paint.

On 8/14/2017 8:59 PM, Eric Greenwell wrote:
> wrote on 8/14/2017 6:24 AM:
>> I used some Mylar that came with adhesive applied and the customer
>> returned after one wing shed its top Mylar after he took the bird
>> near redline! That's when I decided the process needed better
>> "tooth"! Without sanding you are asking the adhesive to hold one
>> smooth surface to another smooth surface.
>
> Did you determine the transfer tape came off the Mylar and not the wing?
>
> I don't see any inherent problem with adhesive adhering to a smooth
> surface, and never had the tape come off the Mylar, but it has come
> off the glider. What preparation do the transfer tape and/or Mylar
> manufacturers recommend?
>

--
Dan, 5J

[[email protected]]

On Monday, August 14, 2017 at 10:59:48 PM UTC-4, Eric Greenwell wrote:
> wrote on 8/14/2017 6:24 AM:
> > I used some Mylar that came with adhesive applied and the customer returned after one wing shed its top Mylar after he took the bird near redline! That's when I decided the process needed better "tooth"! Without sanding you are asking the adhesive to hold one smooth surface to another smooth surface.
>
> Did you determine the transfer tape came off the Mylar and not the wing?
>
> I don't see any inherent problem with adhesive adhering to a smooth surface, and
> never had the tape come off the Mylar, but it has come off the glider. What
> preparation do the transfer tape and/or Mylar manufacturers recommend?
>
> --
> Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
> - "A Guide to Self-Launching Sailplane Operation"
> https://sites.google.com/site/motorgliders/publications/download-the-guide-1
> - "Transponders in Sailplanes - Dec 2014a" also ADS-B, PCAS, Flarm
>
> http://soaringsafety.org/prevention/Guide-to-transponders-in-sailplanes-2014A.pdf

I have encountered the same issue JJ described. As a consequence I always scuff seals as he described.
FWIW
UH