Applying New Seals

[Randy]

I am planning to place an order for control seals and tape to reseal
my glider (304CZ). For those of you who have recently done this to
your glider, what can you share to make this an easier job for me
to do?
Are there any special technics or tools required?
Any additional sealing information would be very much appreciated.

Randy

N304BU

[Stephen]

I got the material from W&W. Clean off all the old seal residue.
Install in 90 degree heated hanger. Put a surface thermometer on the
wing to ensure the fiberglass is 90degrees. Now have someone run a
heat gun ahead of the second person applying the dbl sided tape
heating the fiberglass surface. Do the same for when applying the
mylar. It takes good heat for the chemicals in the dbl seal tape to
make a good bond. then apply the transfer tape. :) Works good last
long time.. I might have some pics if you want them.. S9

[JJ Sinclair]

After 30 years in the repair business, I found the only way to insure
the mylar didn't lift was to sand both the inside of the mylar and the
corresponding wing (stab, fin) with 220 dry, then wipe both surfaces
with acetone just before applying double back sticky. Keep the DBS
straight as an arrow and then follow it in order to keep the Mylas
straight without any kinks. Sand only the 10mm area where the DBS will
go. If you get a kink, make a cut to remove it and press on.
I believe a good mylar job is all that in needed (internal seals not
necessary).
Cheers,
JJ

[William Elliott]

JJ,

Do you agree with the requirement for heat?

WE

[uncl...@ix.netcom.com]

> JJ- Hide quoted text -
>
> - Show quoted text -

I would add emphasis that ALL previous residue has got to be off which
may require more than 220. Then finish with
220.
It is also very helpful to deflect the surface away from the seal
while curing. If you do both sides at once and come back the next day
to popped seal, the natural tendancy is to rub it back down. Likely
this will go on until you rip the whole thing off and do it again.
Wanna know how I know? Nah
UH

[JJ Sinclair]

> JJ,
>
> Do you agree with the requirement for heat?
>

> WE- Hide quoted text -

>
> - Show quoted text -

I haven't tried heat, it may work. The proof is in how long it stays
down. The stuff isn't cheap and quite a bit of work to replace. I have
used a heat gun to help remove the old DBS. Heat it up till you can
roll up the goo with your thumb. No problems since I started sanding
both surfaces. The mylar on my Genesis is about 9 years old now and
none of it has lifted. I even used 2 or 3 layers in places to build up
a low spot after replacing the left aileron with an early unit that
was a tad thicker.
Cheers,
JJ

[T8]

Tips for removing seals:

1) use a hair dryer or heat gun to warm things up. At 100 F plus, the
seal can usually be peeled back (slowly) span wise and take virtually
all of the adhesive residue with it. Work the heat gun on the area
just ahead of the peel point. Go slow, don't overheat. Your should
just be able to hold a finger or thumb on the heated surface. 110 -
120F. Most people can't keep a hand on 120F or more.

2) clean remaining residue with 3M red can adhesive remover. Good
chemical resistant gloves recommended.

Tips for application:

1) Clean gelcoat with 3m adhesive remover thoroughly.

2) Apply bonding tape, DO NOT STRETCH. It must be straight.
Everything must go down stress free. Rub down with metal spoon.
Leave cover (non-adhesive) film in place for now.

3) Position Mylar where you want it. It must be absolutely stress
free & straight. Hold in place with strips of electrical tape (gap
seal tape) about 4 inches long every foot. The gap seal tape goes on
span wise, more or less as you would anti-peel tape. The leading edge
of the mylar must be exactly in line with the leading edge of the
bonding tape.

4) Fold back the mylar on the hinge created by the gap seal tape,
tape it with more gap seal tape to hold it folded back and clean
underside of mylar with adhesive remover. Let dry (30 seconds).

5) Remove protective film from bonding tape.

6) Now work carefully from one end, "roll" the mylar into place on the
gap seal tape hinge. The objective is to bring the entire bonding
surface into very light, continuous contact. After the whole seal is
lightly in contact, rub down with spoon.

7) Clean top side of mylar and just ahead on wing with adhesive
remover. Apply safety tape. Do not stretch.

If you do that as I've described, you don't need to sand anything.
That said, sanding probably doesn't hurt.

This all goes best on a minimum 70 degree day. I agree that some heat
helps establish the bond. If in doubt, warm things up with a hair
dryer and rub down again. Final tip: don't try to do this under time
pressure (i.e. on flying day). Do it fast and sloppy... do it again
real soon. Do 'em correctly, they last for years and years. Make
certain that trailer fixtures maintain control surfaces in neutral
position.

I have had problems with adhering to routed out composite surfaces
(e.g. ASW-24 ailerons). I suspect one way to deal with this is paint
the surface with a very thin coat of epoxy and allow to cure fully
before applying sealing materials. Have not had to try that yet.
Better ideas?

-Evan Ludeman / T8

[hretting]

What if the top white glossy 'safety tape' has started to peel but the
mylar gap seal is still attach firmly with no issues. Is this an
indication that the mylar is in need of replacement or simply clean
the mylar surface and re-apply the safety tape?
Thanks,
R

[uncl...@ix.netcom.com]

Thin CA glue seems to work as a surfacer that helps when bonding to
routed surfaces. Tape seems to like the smoother surface.
Epoxy works well but CA is instant.
I still sand and scrape carefully.
FWIW
UH

[Tom]

There have been accidents when the Mylar was not installed properly,
came loose, which disrupted the airflow over the control surface,
causing a major change in controllabilty.

If you don't REALLY know what you are doing, it is better to have it
done by a professional. This is a serious task.

Tom

[T8]

On Oct 4, 2:52 pm, unclh...@ix.netcom.com wrote:
>
> Thin CA glue seems to work as a surfacer that helps when bonding to
> routed surfaces.

1001 uses. Noted.

-T8

[uncl...@ix.netcom.com]

I've seen safety tape so old you could almost blow it off while seal
bond was just fine.
If bond is good, don't mess with it. Clean up well and replace safety
tape.
Usually every couple years is good enough.
Seems most folks only pay attention when it is falling off.
Safety tape is quite important on elevators especially.
UH

[Dave Springford]

Go to Lee Valley Hardware and buy the plastic Razor blades. You can
use these to remove the tape gunk and not damage the gelcoat or Mylar
while scraping.

http://www.leevalley.com/US/wood/page.aspx?p=53612&cat=1,43456,43407,53612



Dave
www.foxonecorp.com

[Eric Greenwell]

On 10/4/2011 5:44 AM, JJ Sinclair wrote:

>
> After 30 years in the repair business, I found the only way to insure
> the mylar didn't lift was to sand both the inside of the mylar and the
> corresponding wing (stab, fin) with 220 dry, then wipe both surfaces
> with acetone just before applying double back sticky. Keep the DBS
> straight as an arrow and then follow it in order to keep the Mylas
> straight without any kinks. Sand only the 10mm area where the DBS will
> go. If you get a kink, make a cut to remove it and press on.
> I believe a good mylar job is all that in needed (internal seals not
> necessary).

I've always used Mylar that already had the transfer tape on it. It
saves me a lot effort and time, and I've never had the adhesive come off
the Mylar.

I prepared the carbon on my ASH 26 E by cleaning off the old adhesive
COMPLETELY, even scraping with a flat Xacto blade or single edge razor,
then sanding gently with a block and 320 grit as JJ describes until only
fresh carbon shows, then cleaning the residue off with acetone.

I apply the Mylar under a very slight tension. When it's all on, I rub
over the adhesive portion with a firm piece of balsa, rag, thumb, as
needed , then follow that with a hard roller, paying particular
attention to "white" places. That's probably easier to do when the wing
surface is carbon instead of gel coat.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)

[JJ Sinclair]

Forgot one thing, I make sure the mylar is secured to the DBS and to
the surface by rolling it very hard with a roller that I made from a
30mm X 10mm bearing mounted on a 12" rod. I press down real hard as I
roll everything twice. I usually buff and wax the ship every other
year (wax every year), then replace the safety tape which is showing
some age (wax after replacing the safety tape). BTW, I believe the
pilot of Ventus that had tape lift on its elevator, had waxed the
surface, then applied the safety tape..........good point to remember!
Cheers,
JJ

[Andy]

On Oct 4, 8:04 am, T8 <tangoei...@gmail.com> wrote:

> 5) Remove protective film from bonding tape.

What I have found works well is to tape the mylar seal in place over
the bonding tape and then peel off a short length of the backing at a
90 deg angle to the mylar. Stick down the mylar in this area then
pull on the backing to expose another few inches and stick that down.
Keep working along the seal until it's all stuck down.

Andy