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-   -   Acetone wipe proseal before or after cure? (https://vansairforce.net/community/showthread.php?t=148881)

spaceflightmeow 04-22-2017 10:29 PM

Acetone wipe proseal before or after cure?
 
Does proseal come off easily with acetone once it's fully cured, or should I clean up any excess/spatters before cure?

I just finished riveting the stiffeners on my tanks. The outsides of the skins were spattered with proseal. I used a paper towel and acetone to wipe down the rivet lines underneath the stiffeners. Is that bad? Should I have waited for a full cure to clean up?

Robin8er 04-22-2017 11:27 PM

It does not come off easily once its cured. Infact Acetone doesnt really work well at all once its cured. Clean it up as much as you can before it cures.

rwtalbot 04-23-2017 02:56 AM

MEK when wet. Acetone doesnt work well at all. Be careful with the MEK

tgmillso 04-23-2017 06:39 AM

Hi Richard. Not sure where you sourced your acetone from, but it worked great for me on both tanks, so long as you clean up the proseal before it is cured. Maybe we have spicier acetone down here.
Tom.

N941WR 04-23-2017 07:23 AM

DO NOT wipe your tanks with acetone or MEK!

Let them dry and then sand off any excess. You run the risk of having the chemicals penetrate the proseal.

I did wipe one of my tanks off to clean it and even though it passed the pressure tests, the one tank had developed paint blisters while the other is fine.

spaceflightmeow 04-23-2017 10:06 AM

Too late, already wiped the stiffener rivet areas down last night (the clock was running with about 10 hours on the cure). Acetone works like a charm.

Reading up on paint blisters...seems like one of those eternal debates:
http://www.vansairforce.com/Communit...ad.php?t=10187
http://www.vansairforce.com/communit...ad.php?t=87616

Have not reached any conclusions or recommended actions. I need to do some more prosealing today. So, how do you clean off proseal from the skins during the riveting process? Do you wait for a partial cure to remove it? Use a different solvent? Sanding seems OK for the external skins, but I also need to clean internal areas, like the rib rivet lines, so I can place the ribs inside cleanly without any lumps of cured proseal underneath.

EDIT: I am using Van's supplied Flamemaster sealant, CS3204 B-2. I am applying sealant to the faying surfaces and riveting while wet, then adding fillet and rivet dome seals. The rivets have been swished around in a jar of lacquer thinner and patted dry prior to installation. (aside: I've decided I don't want to wait for a partial cure prior to riveting, so that I can get the best squeeze-out. So all of this is done within the 90 minute working time after mixing sealant).

DanH 04-23-2017 12:59 PM

Quote:

Originally Posted by N941WR (Post 1167677)
DO NOT wipe your tanks with acetone or MEK!

Come on Bill...do the reading. MEK is a Flamemaster-approved cleaning solvent.

Per Flamemaster's Application Document, Rev.III, 01/15/07:

Cleaning Solvents
1. Isopropyl Alcohol TT-I-735 E
2. Methyl Ethyl Ketone (MEK) ASTM D740 E
3. Naphtha TT-N-95 E
4. Solvent Cleaning Compound MIL-C-38736 E

Industry standards, per AIR4069a, revised 05/98:

A solvent mixture consisting of (by weight)

Aromatic naphtha (containing 30 parts toluene) 50%
Ethyl acetate 20%
Methyl ethyl ketone 20%
Isopropyl alcohol 10%

or (non-photochemically reactive mixture)

Toluene 18.5%
Ethyl acetate 35.5%
Methyl ethyl ketone 36.0%
Isopropyl alcohol 10.0%

or "other solvents used successfully"

a) ASTM D 740 Methyl ethyl ketone (MEK), technical grade
b) Naphtha, aliphatic
c) Naphtha, aromatic
d) Toluene, technical grade
e) Dry cleaning solvent, high flash

Some of the manufacturers reduce to Class A viscosity by thinning with MEK.

A "blistered builder" survey conducted among vans builders did not find MEK usage to be a common factor.

N941WR 04-23-2017 02:36 PM

Quote:

Originally Posted by DanH (Post 1167752)
Come on Bill...do the reading. MEK is a Flamemaster-approved cleaning solvent.

Per Flamemaster's Application Document, Rev.III, 01/15/07:

....

Dan,

You say all you want but while I had my plane home for the engine swap, I cleaned up some excess proseal on the top of the left wing, in preparation for painting and now, a few years after painting, the only place I experienced paint blisters is on the top of the left tank.

No blisters on the bottom of the left tank or on the right tank.

Why risk it? Since it is easy enough to let it harden and then remove with little risk of future leaks.

In fact, my plane has been flying nine years now, painted for five and I just noticed another blister on the top of the left tank.

If you have a better reason why the top of left tank is developing these blisters and not the bottom or the right tank, I'm all ears.

g zero 04-23-2017 03:12 PM

Blisters
 
Quote:

Originally Posted by N941WR (Post 1167765)
Dan,

You say all you want but while I had my plane home for the engine swap, I cleaned up some excess proseal on the top of the left wing, in preparation for painting and now, a few years after painting, the only place I experienced paint blisters is on the top of the left tank.

No blisters on the bottom of the left tank or on the right tank.

Why risk it? Since it is easy enough to let it harden and then remove with little risk of future leaks.

In fact, my plane has been flying nine years now, painted for five and I just noticed another blister on the top of the left tank.

If you have a better reason why the top of left tank is developing these blisters and not the bottom or the right tank, I'm all ears.


Check your fuel tank vents . I hanger my plane and always release the fuel caps after pulling it it . They are ready to check fuel level before next flight but also can vent without any pressure . If any fuel gets in the vent the tank would have to gain 1/2 psi to push it up and over the vent loop ( RV8 ) . Might be totally bs , but nothing to loose

N941WR 04-23-2017 03:25 PM

Quote:

Originally Posted by g zero (Post 1167777)
Check your fuel tank vents . I hanger my plane and always release the fuel caps after pulling it it . They are ready to check fuel level before next flight but also can vent without any pressure . If any fuel gets in the vent the tank would have to gain 1/2 psi to push it up and over the vent loop ( RV8 ) . Might be totally bs , but nothing to loose

I've never had a pressurized tank as indicated by a sound when opening the caps, as you describe. Like you, my plane is hangared and as I described above, my issue has only happened on the one tank that was cleaned with MEK prior to painting.

What I'm saying is simply, why risk it?

No one has come up with a good reason for the paint blisters and in my case, I'm pretty sure it was caused by the use of MEK.

In fact, I was talking with another RV builder who also worked for an airline manufacturer. He told me their SOP was to never clean the excess proseal off with any type of solvent because it can produce leaks later on. Sounds kind of suspicious to me.

RV7A Flyer 04-23-2017 05:37 PM

Quote:

Originally Posted by N941WR (Post 1167784)
I've never had a pressurized tank as indicated by a sound when opening the caps, as you describe. Like you, my plane is hangared and as I described above, my issue has only happened on the one tank that was cleaned with MEK prior to painting.

What I'm saying is simply, why risk it?

No one has come up with a good reason for the paint blisters and in my case, I'm pretty sure it was caused by the use of MEK.

In fact, I was talking with another RV builder who also worked for an airline manufacturer. He told me their SOP was to never clean the excess proseal off with any type of solvent because it can produce leaks later on. Sounds kind of suspicious to me.

And yet...I cleaned up after riveting with *liberal* use of MEK on the tanks...4+ years, nearly 500 hours, no blisters.

I suspect something else is going on that is causing them for most people...or several something elses. We may never know, but it's far from clear that cleaning up with a solvent after riveting is a cause. If it were, I suspect there'd be a significantly higher number of people with blisters under the paint...


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