Blog

January 30, 2020

The Secret to a Leak Free Windshield on Your Classic

If you’re a Steele customer or you’ve seen our advertising you know our main focus is making parts designed from originals so they fit like they came from the factory and, in turn, won’t leak. However, when it comes to your windshield, rear window or any other stationary glass in your vehicle, it takes more than a superior gasket to avoid leaks. There’s an extra step you should take to seal between that gasket and the body of the vehicle- you need to use Automotive Bedding and Glazing Compound.

What is Bedding & Glazing Compound?

Bedding & Glazing Compound is a sealer designed specifically for creating a watertight seal between the windshield rubber gasket and auto body. Here at Steele, we recommend the 3M brand (3M part number 08509).

It is a rubber-based formula that never hardens so it remains flexible. That makes it the perfect solution for sealing glass and acting as a buffer for the window on a vehicle that’s always shifting and vibrating. 

It also:

  • Has non-sagging properties making it great for vertical and overhead applications
  • It’s a one-part sealer so there’s no mixing required
  • Comes in a caulking tube for easy application.
  • Did I mention that it won’t harden or crack EVER?! This stuff is amazing.

Side Note: Urethane Adhesive should NEVER be used in place of Bedding & Glazing Compound. Urethane Adhesive will bond windshield, gasket and body together and you’ll have problems replacing the windshield if you need to later on. Urethane Adhesive might look similar but is a much different product and we only recommend using it in place of butyl tape when gluing in your windshield. For more information about Urethane Adhesive read our article Where has all the Butyl tape gone?

When should you use Bedding & Glazing Compound?

When installing a window – windshield, rear window, rear quarter or any other glass that uses a rubber gasket. You can also use it to repair leaking areas.

Why should you use Bedding & Glazing Compound?

For a truly leak free window you need to seal any and all places that water can get in. Gaskets are made to fit to the glass exactly and when you put them onto the vehicle, they fit into the allotted space well but do not create a watertight seal. Taking the extra step to use Bedding & Glazing Compound will seal everything up and avoid that dreaded wet carpet, water dripping on the dash and ultimately, rust.

Bedding & Glazing Compound was used on the assembly line when these classic cars were new so it’s certainly not a step you should skip in your restoration.

How do you use Bedding & Glazing Compound during a gasket/glass installation?

Materials needed:

*Just a warning- this can get messy, but it’s worth it.

Once you’ve removed the old windshield/back window and gasket, clean the body where the gasket will lay. Making sure this area is clean and free of debris will help the Bedding & Glazing Compound do its job.

Because of the above mentioned mess, the next step we’d recommend is taping around the window opening with some Auto body tape. This will make cleanup a breeze- and possibly lower your stress levels too.

For locking strip type gaskets that are installed on the pinch weld first, lay a bead of Bedding & Glazing Compound on the pinch weld all the way around the opening and push the gasket on as usual. If your gasket is installed on the glass first, lay a bead of Bedding & Glazing Compound on the body of the vehicle where the gasket will lay on it. Lay another bead on the underside of the gasket and install the glass as usual. Be sure to use spacers and/or tape to hold everything where it should be until it cures.

If your vehicle allows you can also install the gasket/glass first and then apply the Bedding & Glazing Compound after (always from the outside of the vehicle) or put some additional on after the installation if more is needed.

Tip: Always apply Bedding & Glazing Compound from the outside of the vehicle. It almost never rains inside a vehicle, so you don’t need it in there.

3M Automotive Bedding & Glazing Compound has a 40-50 minute working time so don’t stress! You can take your time and still get the glass placed before anything starts to set up.

Once everything is in place, go back with a dry rag to clean up. You can also use denatured alcohol, if needed.

Bedding & Glazing Compound cures in as little as 24 hours so leave it in a dry, safe place for a day or two and you’re all set.

How do you use Bedding & Glazing Compound for repairing a leak?

Locate the area of the leak.

Apply Bedding & Glazing Compound to the area making sure to squirt it into any gaps or open areas. Again, always apply it from the outside of the vehicle.

Clean up and wait at least 24 hours and test it to see if it leaks again.

Do you have a technical question about our products? Or would like to request instructions for installing a product we sell? Let us know! We’re happy to help get your ride #SealedWithSteele!


Steele not only has all the products you need but all the knowledge you need to get the job done right, too. If you have questions about Rubber Parts or Weatherstripping on your Classic Car, Truck, Hot Rod or even your boat, trailer or RV, feel free to reach out to us! You can call us at 800-650-4482, contact us through our website or comment on this post and we’ll get you answers as quickly as possible. Check out our YouTube channel for our full library of how-to/installation videos.

Steele Rubber Products, located in Denver, NC, is a manufacturer and seller of high-quality rubber parts and weatherstripping products for classic and vintage automobiles, hot rods, RVs and Boats. Steele offers more than 12,000 parts for cars and trucks as well as a large line of universal weatherstripping and rubber parts to be used on any project. Established in 1958, Steele is a trusted name in the automotive restoration industry. 

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