How to Fill a Crack on a Clear Glass Door Knob

Who doesn't love a door with a glass door knob? Antique glass door knobs have been manufactured since the early 1800s. They became very popular in the early 1900s, because metals were needed for wartime. This led to a variety of designs including 6, 8 and 12 point faceted glass in ovals, spheres and squares. Most glass door knobs were clear although cobalt, Robin's egg light blue, red, green, violet and Vaseline glass were also formed into door handle works of art. Bullet, star and pinprick designs embellished antique glass door knobs and now the rarest designs fetch a high price. Since then, glass doorknobs never went out of style. There are rare hand cut, colored, crystal door knobs which are pricey items still being sold in flea markets and antique stores. Luckily, glass door knobs are quite durable, but there are times they do sustain damage, and sometimes need repair.


  • Superglue
  • Silicone Adhesive
  • Masking Tape
  • Razor Blade
  • Clean Rags

Step 1. Preparation: Removing Your Glass Door knob

It is a good idea to start by removing your glass doorknob for repairs. You can then clean the areas and hardware around it. This will also give you a chance to tighten the glass door knob, which tends to wiggle and slip over time. Glass doorknobs are attached by a small set screw on the collar. Loosen this until you can unscrew the collar from the post or spindle. Leave the set screw in the collar. If your glass door knobs spins but doesn't open the door, now is a good time to replace the square post. Take a dry piece of rag, any old t-shirt will do, and wipe around the collar carefully removing dirt and grime around the doorknob.

Step 2. Repairing a Crack

Glass doorknobs can develop hairline cracks. The simplest solution is to apply superglue to the area and wipe off any extra residue. If you are concerned that your glass doorknob might be cracked enough to break while in use, you may simply want to replace it. Reproductions and original antique glass door knobs can be found at yard sales, antique shops and online starting at about $20. If the doorknob has already broken into 2 pieces, apply superglue to both sides and tape together with masking tape. Let dry overnight. To test the bond put the doorknob in a heavy sock and gently tap on the floor. If the pieces separate, you can try to glue them again or it might be the signal that it's time to replace it altogether.

Step 3. Securing Your Glass Door knob

Sometimes the problem with glass door knobs is that they become dislodged and fall out of their collar. For this problem, use your silicone-based glue to re-secure them. Add a generous amount of silicone glue to the collar and embed the knob into it. Make sure not to fill the area around the threads or to inadvertently glue the set screw in place. Let dry overnight and cut off any remaining silicone with your razor blade.