Jump to content

Bullet Proof Window Repair


Recommended Posts

OK-- Did I get your attention? HOPE SO! 

I am working on the 76 Cadillac "BULLET PROOF" limo  surplussed out by the DOJ.  All the windows are curved and "glued" together consisting of an outer layer of Polycarbonate sheet 1/4" thick. Under that are two solid 1/2" layers of glass. Between each of the three pieces is some type of rubber material (silicone?) and a type of clear epoxy that seals and binds all three layers into one unit. VERY HEAVY!

What has happened is, the 1/4" poly has gone bad and crazed. I have removed all of that and have the glass exposed, However, there has been some degradation of the "epoxy" material holding these together. This is where I need some help to remove this material, binding the glass together so I can clean and polish the glass.

I have tried Acetone, Lacquer thinner and some solvents. Nothing works. 

I have also taken one of the windows (yep, the smallest one) to a couple glass companies and they dont want anything to do with it and zero help.  

 

Any ideas??? 

Link to post
Share on other sites
9 minutes ago, Rusty_OToole said:

Now you have me curious, what are you planning to do with this thing if you get it on the road? And did you try wet sanding and polishing the windows like a polycarbonate headlight?

The poly will be replaced- the glass is nice, but has the silicone type material between the glass that is foggy. Easy to clean the glass, but not until I can get the pieces apart.

The car is almost ready for the glass... Think about what wet concrete/fiberglass mixture did to the doors and exterior sheet metal.. All the exterior panels rusted from inside out. Roof had a layer of mortar and a kevlar/cloth type material under a typical vinyl top covering. So it too was rotted and had begun to collapse into the pristine interior. 

 

The car will be part of a museum collection of other cars (some with interesting history) located in Vienna Austria. This car having been purchased  by the DOJ Washington DC to include the presidential flag holders, dual electrical systems, radio gear and hidden lights and siren and assigned to the northern area of Los Angeles California, kind of takes on some kind of Presidential Use???  Yes, I have the log book!

Link to post
Share on other sites
56 minutes ago, nickelroadster said:

There is no solvent that will take epoxy down.  I think you may have to use mechanical means to do this.  Hopefully one of the makers of armored cars will be able to help you with a method.

It is not a hard epoxy---- It is a rubbery-like material that looks and feels like a silicone material. But sticks like glue.

Link to post
Share on other sites

Between the two glass layers, it's likely that PVB (polyvinyl butyral) was used in a high pressure/high temperature autoclave.  There isn't any practical way to get the glass layers apart by dissolving the PVB.  Sticking polycarbonate (Lexan, etc.) to glass is extremely difficult.  See this patent:  https://patents.google.com/patent/US4204025.  This is not a task for the amateur, special equipment and chemistry knowledge is needed, plus a lot of experimentation.

 

If you have somehow peeled the polycarbonate from the glass, polish the glass with some soft jeweler's rouge and Bon Ami and leave it.  This ought to be enough for a museum car.

Link to post
Share on other sites
4 hours ago, Gary_Ash said:

Between the two glass layers, it's likely that PVB (polyvinyl butyral) was used in a high pressure/high temperature autoclave.  There isn't any practical way to get the glass layers apart by dissolving the PVB.  Sticking polycarbonate (Lexan, etc.) to glass is extremely difficult.  See this patent:  https://patents.google.com/patent/US4204025.  This is not a task for the amateur, special equipment and chemistry knowledge is needed, plus a lot of experimentation.

 

If you have somehow peeled the polycarbonate from the glass, polish the glass with some soft jeweler's rouge and Bon Ami and leave it.  This ought to be enough for a museum car.

I am probably not using the correct terms here... So MANY variations of plastics!  ALL of the outer "plastic" came off very easy. The "rubbery" clear material between the outer 1/4" plastic also removed very easy, actually falling off... NOW I have the two curved glass pieces 1/2" EACH to pull apart in order to removed the discolored material between them. These are not laminated "safety glass" pieces. They have not been bonded by pressure/temp. process.  Total thickness of three layers of glass, plastic and rubber binding layer, 1 3/8"  

Link to post
Share on other sites

Rather than getting the glass pieces separated, perhaps you can use the glass assembly as a form to make some new windows from acrylic (Plexiglas) sheet 1/4"-1/2" thick.  A good sign shop can probably do this for you.  They can form the acrylic to the shape of the glass by heating it to 300-350 °F, then trim to size.   If the car is going to sit in a museum with the windows rolled up, no one will know that the windows aren't really 1-1/2" thick.  Even if you got the glass apart, it would require a lot of work/technology and vacuum bagging to put the pieces back together without bubbles.  Are original, non-bulletproof glass windows available?     

Link to post
Share on other sites
  • 5 months later...
On 8/6/2018 at 12:39 AM, jp928 said:

Normal epoxy will soften with methanol - I know that from using 80% methanol fuel in R/C models and the impact of leakage on epoxy glues. Cant hurt to try ?

jp 26 Rover 9

It’s actually the nitro methane that soften the epoxy. The more nitro, the more severe the reaction. Most epoxy paint is good to about 25% nitro methane model fuel if wiped off within a reasonable time frame.

Link to post
Share on other sites
  • 2 weeks later...

Try methelyne chloride based paint remover. I have used it to remove fully cured epoxy glue from surfaces. Just remember that it is very nasty stuff to work with, and proper safety equipment is a must. I wear chemical resistant full length gloves, a rubber apron, and a full face  respirator. And I work outdoors with it, as the fumes are corrosive and will cause flash rust to form on bare metal surfaces exposed to the vapor.

 

I used to refinish furniture for a living, so I have a lot of experience with this chemical. I really don't like working with it, so I have gotten away from refinishing, and only have occassional need of it.

  • Like 1
Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...