Thanks Wayne - another little gem of information that will save
a builder (or 2 or 3 !) , hours and hours of grief !!!
Things like this really demonstrate the value of this list !!
Thanks Mike, for the list, and Wayne for the content !!
Can't say about Wayne, but it's about time to send a donation
along to Mike .... It costs him time & money to keep this thing
running ! Strictly voluntary - and I know some of you donate
regularly .... His mailing address is on the home page ...
(<I> will NOT use PayPal ! Some do ... )
......bobp
bobp@prosumers.ca
bobp@pattersys.com
http://www.Pattersys.com
http://www.amway.ca/BobPatterson
De-fenestrate now ! Linux is the answer !
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On Wednesday 23 November 2011 19:38:46 Wayne G. O'Shea wrote:
Was into a real mess on this wing tank fabrication that I'm currently on.
The previous builder had built wet tanks.. skipped a LOT of attention to
detail and gave up on trying to fix leaks years later. They cut all the rib
and stringer structure apart and installed fiberglass tanks, leaving the
wings with no compression or tension strength in the first 3 bays, which
unfortunately had the new aircraft owner in a terrible place. In between
that work they had tried the sloshing compound fiasco and it was everywhere
as well. It was bonded REAL nice to all the flat surface though, but of
course it will never seal gapping holes or skin overlaps that were never
prosealed in the first place.
So once I had the wings all torn apart... the tanks out, wing ribs
removed.. top and bottom tank skins gone and wing skins cut back.... rear
fuel tank bulkheads tossed in the big round can, I still had a pair of
main spars and their skin overlaps coated in all this crap. So while
browsing ACS to order some new Proseal 890B-2 I noticed a product called
Polygone..........
"PolyGoneT stripping agents are unique formulations that remove polysulfide
(PRC) and silicone RTV sealants from metal, ceramic, and some plastic
substrates. The top polysulfide producers include PRC DeSoto (now PPG), AC
Tech, and Flamemaster. The top silicone producers are GE, Dow, and Wacker.
Both polysulfide (polysulphide) and silicone RTV are difficult to remove
completely since they actually bond into surface/substrate. The typically,
sealant removal method requires scraping that results in damaging the
substrate. There are also products that try to "disslove" the sealants but
due to their inertness, this does not work. PolyGone however, reacts with
the polymers chemically and breaks them down so they can be rinsed away
without damage to the surface/substrate. This offers significant advantages
over other removal methods. PolyGone emulsifiers are specialty blended
chemistries that wet and penetrate the polymer and relatively quickly
emulsify it. This emulsification prevents redeposition of the reaction
by-products and allow for water rinsing"
Figured what the hell, I'll give it a try and if it saves hours and hours
of labour trying to mechanically remove the mess.... or risking my eyes to
a gallon of MEK then the $210 per 5 lb pail of the stuff would be a great
investment. Well today and yesterday I gave it a whirl. I brushed on the
gel (that stays absolutely in place even upside down) and then poked it
around with the brush every 30 minutes as per the directions. This stuff
doesn't just lift the sealer it actually emulsifies it and pulls it up out
of the aluminum pores. After about 4 hours I used a plastic scraper to
remove the majority of the sealant and slosh. Stubborn spots I recoated
and left overnight. Today I scraped most of that off easily and a few
spots needed another splash of remover and about an hour later I had
everything looking like shinny new aluminum ready for a good scotchbrite
crosshatch and new parts to rivet / seal in.
The nice thing is that this stuff has no odor or fumes and it can be rinse
with water if you like (or you can use acetone). It also eats and removes
epoxy primer, as you can see in the pictures where the third bay was
painted and not part of the original 2 bay wet wing.
Never again will I fight like mad, trying to mechanically remove the
proseal from a badly prepped area of skin / rib or bulkhead to fix a tank.
Even at a cost of $210, for a 5 pound pail, I figure I saved the customer
at least double that in labour by using it. Now that I've seen how far it
went, I probably could have got away with about 3 x 6oz packs @
$21.50each. instead of the 5 lb pail. Oh well... if someone has a spot
they need to clean send me an email and I'll put some in a heavy ziplock
container or similar for you. It has a one year shelf life, if kept cool
and in the dark.
Before..
http://www.irishfield.on.ca/gallery/polygone1.jpg
The stuff...
http://www.irishfield.on.ca/gallery/polygone.jpg
Stuff starting to eat..
http://www.irishfield.on.ca/gallery/polygone2.jpg
http://www.irishfield.on.ca/gallery/polygone3.jpg
http://www.irishfield.on.ca/gallery/polygone4.jpg
After first scrape...
http://www.irishfield.on.ca/gallery/polygone5.jpg
Second coating..
http://www.irishfield.on.ca/gallery/polygone6.jpg
A little plastic persuasion..
http://www.irishfield.on.ca/gallery/polygone7.jpg
After wiped with Acetone..
http://www.irishfield.on.ca/gallery/polygone8.jpg
Regards,
Wayne
PS... and yes Gary you can use it if you need something for the RF
magazine!
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