Transparency While Loop Help?

So, first, imagine solving this problem without the context of Touched.

We would do exactly what you said:

while true do -- a while loop
    wait(0.2) -- every 0.2 seconds
    local bsTransparency = b.Transparency
    b.Transparency = bsTransparency + 0.1 -- 0.1 added to b's Transparency
end

Then we just can put this inside of our touched function:

local b = script.Parent

function onTouch(part) 
    while true do -- a while loop
        wait(0.2) -- every 0.2 seconds
        local bsTransparency = b.Transparency
        b.Transparency = bsTransparency + 0.1 -- 0.1 added to b's Transparency
    end
end 

b.Touched:connect(onTouch)

This will more or less work. Two ideas to improve it: add a debounce and reset the transparency to 0 each time it gets touched.