This transparency loop should take 0.1 transparency every 0.5 seconds, but it won't?

This script should minus the parts inside the model's transparency by 0.1 every half a second after a button is clicked, but it only changes the transparency of 1 part.

Script:

local model = workspace.model1:GetChildren()
local button = workspace.button1.ClickDetector

button.MouseClick:Connect(function(onclicked)

for i,v in pairs(model) do
    repeat
        v.Transparency = v.Transparency - 0.1
        wait(0.5)
    until v.Transparency == -0.1
end

end)