Replacement Kiln Vent Plugs

 

Replacement Kiln Vent Plugs

Accidents happen.  Sometimes the lightweight plug for the vent of a kiln gets dropped and broken.  You can replace this, whether brick or ceramic.

A quick solution is to roll up some fibre blanket or thick fibre paper into a roll large enough to fit into the hole.  This is enough to keep the heat from escaping and stop outside air flowing in.  If you leave excess outside the plug hole, it allows you to pull it out and view the interior as usual.  This will last quite a while and can be renewed easily.

A more permanent solution is to shape soft fire brick.  This can be shaped with a cheap saw. The brick is soft but very abrasive. So, use a cheap saw or an old one.  I keep an old saw especially for shaping bricks and vermiculite.  You could use 50mm/2 inch vermiculite in this way too, but firebrick this thick or more is easy to obtain.

Cut a cube from a fire brick.  This usually is about one third of a full brick.

Mark all around with a pencil how thick the shoulder (the outer part of the plug) should be. 25mm or 1 inch is thick enough.  It is possible to have it thicker if you wish.  The important element is that the outside part of the plug should not over balance the neck that fits into the vent channel.

Present the brick to the vent hole and twist a little, this will leave a mark to determine the diameter required. Alternatively, measure the inside diameter and draw this onto the end of the brick with a soft pencil or charcoal.

One end of brick cube marked, although a little off centre

Saw down to the shoulder mark on each of the four corners. Then make it eight corners. Test how well this adjustment fits to the hole.  It is probable that it is too big on the corners, but ok on the flat sides.

The first four corners sawn off to the shoulder

This is the time to use a wood rasp to round the multiple corners. Repeat the testing for size and adjusting until the plug fits the hole.  

The plug should not be tight.  It needs only a loose fitting so that it is easy to remove and put in.

Fit too tight to slide easily into the vent.

Finally, with 60 grit sandpaper round off any remaining corners.  Test and sand more off until it slides easily into the hole. This should not take more than a quarter of an hour to complete.

 

Fit just right. It slides in and out easily.