Windshield Repair Forum

This may be a dumb question.But what's the purpose of the upper seal?Seems to me the lower o-ring seal would keep any air from entering the upper chamber since the lower seal does not enter into the larger chamber, so how does the air get past the lower seal to evacuate the air out of the upper chamber?

Magic is the answer grasshopper Its like the how does the microwave work question who knows as long as it works I go with the flow that semester in science class was the worst ten years of my life

As far as I'm aware the air removed by the vacuum process is not expelled past the lower piston seal. The air is pulled through the resin by the length of the piston stroke - the resin then flows into the damaged area initially by gravity and then by the vacuum which has been created in the damaged area. On releasing the plunger, it is the initial removed compessed air (now trapped) between the glass surface and the lower 'O' ring, which then creates the pressure cycle and forces the resin to circulate around the stonechip damage with the assistance of the compressed pressure which has been created in the main chamber. The 3/4"seal in the main chamber creates the pressure cycle to assist the vacuumed damaged area pressure, by pushing the resin into the stonechip area, ready for curing. Might be wrong but that is how it was explained to me - omg did that make any sense?

I'm so amazed I can't even find the words to respond.