# Butyl Rubber removal from plastic

#### KeepItSimpleStupid

Joined Mar 4, 2014
3,636
Can't figure out where to put this. Automotive possibly? I'm replacing the vapor barrier on a door of a car after a door speaker install.
So, it's a flexible plastic sheet to painted metal seal. Nearly all of the adhesive is on the plastic. Wish I still had access to LN2.

The area around the plastic was marked with a stadtler. The plastic vapor barrier was removed. The adhesive is off of the metal side of the door.
I removed a very small portion of adhesive, about 8" x 1/4" from a small piece of plastic and re-attached it.

Presently, putting the adhesive on the door using the vapor barrier as a template. The adhesive comes in tape form 50' x 14" x1/8" with a wax like paper backing. You apply one side and then remove the backing and apply the other.

Tools used so far:
Knife
vinyl gloves
Nitrile gloves
Scissors
Kapton tape
paper towels
Giant and intermediate sized cotton swabs

Solvents used so far:
Naptha
Hexane
Ligher fluid
Goo gone
Methanol - not for Butyl rubber

So, any other suggestions? I had a lot of trouble obtaining Naptha.

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#### jpanhalt

Joined Jan 18, 2008
8,063
VM&P Naptha (varnish makers and painters naptha) is still plentiful in Cleveland, including the big box stores. Another term for light hydrocarbons is "ligroin," which is usually sold by temperature range for distillation, e.g., 50-60 distills at 50° to 60°C. That is pure hydrocarbon with maybe a little aromatics. Stoddard solvent includes some aromatics and is slightly stronger. I take VM&P and add about 10% toluene (preferred) or xylene to get about the same. Much better than goo be-gone. Both are pretty gentle on modern automotive finishes.

#### shortbus

Joined Sep 30, 2009
7,074
Your wanting to remove the butyl, but don't quite understand from what? The vapor barrier? The trim panel of the door? I see John beat me to it.

If you are just going to replace the vapor barrier, why remove the butyl? I have always just stuck the visqueen type of barrier back to the door with the original existing butyl. And maybe a short piece of duct tape if it doesn't hold real good. The interior panel will hold it in place after it is clipped back on.

Automotive lacquer thinner wit usually cut the butyl if it is just a thin layer. Don't know what it will do to the VB though. The butyl sticks really good, they use it to glue in windshields and after cutting the left over butyl when replacing a windshield I've cleaned the final thin layer off with lacquer thinner. Tried one time to not clean it all off but got a leak doing it that way so clean down to paint now.

#### jpanhalt

Joined Jan 18, 2008
8,063
I agree, lacquer thinner will probably remove most caulk. I was concerned about the plastic (acrylic?). Lacquer thinner will attack it almost instantly. Unfortunately, the effects of hydrocarbon solvents (hexane, ligroin, Stoddard, 10% toluene -- roughly in order of strength) are not always immediate. Crazing can occur months later, and the stronger the solvent, the more likely crazing. I have seen oil-based rope-clay caulking (as recommended by some aircraft manufacturers) cause crazing on acrylic windshields. That is an expensive repair.

#### KeepItSimpleStupid

Joined Mar 4, 2014
3,636
Your wanting to remove the butyl, but don't quite understand from what? The vapor barrier?
Basically, the vapor barrier refuses to stick. Sometime ago, maybe 5 years, I did some sort of repair where I removed the vapor barrier. When I took the door off this time, the vapor barrier fell off in areas, so I tacked it back in places with Kapton tape. The passenger door was fine.

So, I did not try to buy the vapor barrier for an 18 YO vehicle. I probably couldn't get it anyway until the GM strike is settled. Before I can put the door back together, I have to order a piece of weatherstrip. The xmas tree nuts are all damaged too. All but 2.

I also broke some faux wood plastic trim on the door. That was fun trying to fix that. It was basically a piece of c-channel that I thought had to come off to expose some screws because it moved. Nope. Crack. I used two EZ-Loc inserts, so the adhesive would have something really solid to bite on along with a plastic glue to glue the edges together.

The painted surface would not be seen. it's the inside of the door. The vapor barrier is some 4 mil plastic sheeting. Again, perfect removal was not necessary. The plastic is sort of a milky color and maybe it's polyethylene.

With the stuff mentioned, I did manage to remove the adhesive. I also have the new Butyl rubber applied to the door.

My hexane was about 46% n-hexane. I don't really know the difference, but for a solvent I know I didn't need pure n-Hexane.

Mcmaster would not ship VM&P Naptha because of the VOC's. The bog box store such as Home Depot won't get it either. I did find it in stock in a nearby state that would have required a 16 mile drive one-way. I did accidentally find it at a Woodcraft store, but I found someone who would ship it to me. Acetone and plastic doesn't get along.

Final prep was wash with soap and water, rinse, wipe with methanol and store flat overnight. A Scotchbrite pad helped. So basically, solvent, and scrape with a dull penknife or sharp razor blade.

In the midst of this project, I attempted to remove some urine damaged hardwood floor sanding and using oxalic acid and finishing with Amber shellac. It's a perfect match. The stuff dries quickly and nearly no odor. The door project got priority because it was 75 degrees outside.

I don't know if I can get Toluene anywhere locally. Although there was/is a Fisher Scientific warehouse nearby. I don;t like toluene anyway. I probably could order it. Toluene might have helped.

#### jpanhalt

Joined Jan 18, 2008
8,063

Surprised shellac is still allowed in your area. Of course,that's an old finish for HWF's. Today, it is mostly polyurethane -- even water based. One room in my house was done with high quality (Bona) water-based poly. Not at all comparable in appearance or durability to the oil-based product.

Anyway, if it was shellac, I agree with sticking with shellac , unless you strip the floor entirely.

#### shortbus

Joined Sep 30, 2009
7,074
So, I did not try to buy the vapor barrier for an 18 YO vehicle. I probably couldn't get it anyway until the GM strike is settled. Before I can put the door back together, I have to order a piece of weatherstrip. The xmas tree nuts are all damaged too. All but 2.
I have my doubts that it is available from GM even without a strike. I would never even think of using butyl for doing a repair like that, the reason it was used on the line is speed, it sticks instantly, no "tack off" time. Since it is never seen unless the door panel is off I'd just use duct tape, and have many times.

The christmas trees are or should be available at any O'reilly's, PEP boys, Autozone, etc. They have a thing called Help products from Dorman, that has that kind of thing, most of the oddball fasteners and other things used by the OEM's.

#### KeepItSimpleStupid

Joined Mar 4, 2014
3,636
Shellac is alcohol based:

Ingredients:
Ethanol
Isopropanol
MEK
Shellac
Water

Voc < 700 g/l

At one point, I was able to take off a heat return register and see both the stained and unstained wood. I got lucky, I used ZInssar Amber Shellac and it matched perfectly. The house ia about 60 years old. No polyurethane then.

#### jpanhalt

Joined Jan 18, 2008
8,063
The point I was alluding to was that most shellac contains a wax too. That wax can interfere with adhesion of any other finish. Special shellacs (e.g., Kilz and Zinsser) that are sold as primers or stain blockers will usually say "wax free" to distinguish them. The ubiquitous polyurethane topcoats are especially sensitive to the presence of wax or oil. That is why when I recently re-finished a beautiful 15-panel entry door, I elected to use an alkyd spar varnish as the original door was done in shellac, circa 1950. (BTW, one has the same issue with polyester resins and epoxy. The wax in polyester resins is needed for a hard surface cure, but it is also one reason you can put polyester over epoxy, but not the other way around.)

#### KeepItSimpleStupid

Joined Mar 4, 2014
3,636
The christmas trees are or should be available at any O'reilly's, PEP boys, Autozone, etc. They have a thing called Help products from Dorman, that has that kind of thing, most of the oddball fasteners and other things used by the OEM's.
Amazon had them. I needed at least 16. 20 for $10.00 USD. They were double level, where they slide and lock into place before pushing them into place. A lot of the teeth were missing on the fasteners. I am looking for felt washers 1/8" thick and a 1/4" hole and a 0.500 to 0.750 in diameter. Right now, I'm going to cut a thicker one. I did destroy a (license plate type of nylon nut) Rectangular hole. It wasn't on any online diagram, and it wasn't on the dealers diagram. He had to call GM for the part number. Price was much cheaper on the bay, but I had to buy at least one from the dealer @$4.50 ea. He quoted a price of about $9.00 ea. In case, I have to remove the door panel again, I placed some labels under the inside door handle. eg. <Remove> for two somewhat hidden screws. The nylon "license Plate" nuts I broke by pulling too hard. They are on a slight angle. And a "DO NOT remove faux trim" label. So, now I have to just put the plastic back on. The door needs the weatherstrip on top of the actual door which I have to order. There are a few screws under the door panel. The stuff is expensive. It also needs the inner door seal which is a continuous strip. I got some molding lube to help install it. Another project is to pull the air bag and replace a steering wheel radio control and the multifunction switch (high beams wont latch). m It;s ben a while since pulled a steering wheel. Did it on a 1968 Chrysler (turn signal) and 1965 Ford (horn issue) vehicle. So, my 50+YO puller won;t work. I bought a nice Gearwrench 80742 Torx set. I know I need an external Torx to take the steering wheel apart. No deep external torx sockets though. I have some external Torx sockets, but really really small like 2.5. The service manual has a different method of disabling the air bags than just waiting 20 minutes after disconnecting the battery. Just as bad as refrigerator gaskets. Price from like$120 to $30 for the same gasket each. I got the freezer door gasket. Thread Starter #### KeepItSimpleStupid Joined Mar 4, 2014 3,636 John: I don't do a lot of re-finishing or painting. I painted a room once. Dad did all of the painting. I think I did it differently than anyone else would. First there was prep. Latex was placed over oil paint on the trim. Ceiling was first. Then I did the trim. It's like who cares if I over paint around the edges a bit. Then the walls. It's easier to remove wall pint from the molding that molding paint from the walls. #### shortbus Joined Sep 30, 2009 7,074 I did destroy a (license plate type of nylon nut) Rectangular hole. It wasn't on any online diagram, and it wasn't on the dealers diagram. He had to call GM for the part number. Price was much cheaper on the bay, but I had to buy at least one from the dealer @$4.50 ea. He quoted a price of about \$9.00 ea.
I go to the Dorman Help at a parts store before ever going to a dealer for things like that.

And here first for weather stripping, https://www.steelerubber.com/

The felt sounds pretty similar to what is used on a thread spool spindle on a sewing machine. I'd check at a sewing machine store for one.