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industrial finishing: MASKING
Preventing Masking
Caps and Plugs
from Blowing Out During Curing
BY LEE LECHNER
TORNADOES CAN HAVE SPEEDS of up to 300 mph. That’s place, the tapered plug design only allows for a fraction of
the same speed your plugs go when they pop out during the plug to grip to the surface. This means that it’s much
the baking process! Just kidding. It isn’t that fast, but it may easier for the plug to pop-out once pressure builds.
look like a tornado went through your curing oven if you’re
not using a cap or plug designed to withstand intense in- THE SCIEnCE bEHInD PRESSuRE
ternal pressure. Don’t let your oven look like a wasteland. When gases, liquids, and solids are heated, they expand.
You can avoid this type of disaster in the future with some When the gas is heated in a closed container (like an air
simple fixes. reservoir tank), the particles collide with the sides of the
container, resulting in pressure. The greater the number of
wHy DO PLuGS AnD CAPS POP OuT? collisions, the greater the pressure buildup becomes.
When you’re plugging a pipe or some other component Enough pressure can result in unwanted results, such as
that is open on one end and closed on the other, there something as simple as a silicone plug popping out.
is no room for air or gas to escape. This causes the in-
ternal pressure to build up during high-temperature bak- PREvEnTInG CAP AnD PLuG bLOwOuTS
ing, ultimately resulting in the dreaded pop (your plug STAnDARD vEnTED PLuGS
popping out). During the curing process, the vent in the plug allows in-
Tapered plugs are the biggest culprit for popouts. Why? ternal pressure caused by high heat to escape. It does this
It comes down to the amount of surface that the tapered by having a small slit (the vent) that opens when pressure
design grips onto. Unlike a pull plug where most of the builds up and gases push outward. This means no more
plug is ‘grabbing’ onto the surface keeping it firmly in plugs popping out.
Graphic demonstrating plug blowing out due to pressure buildup. Silicone Vented Tapered Plug.
16 CAnADIAn FInISHInG & COATInGS MAnuFACTuRInG nOvEMbER/DECEMbER 2020
