overriding `Base.show` with Crayon act differently than `printstyled`

This was what I've been doing

using Printf
struct Foo
       val
end
function Base.show(io::IO, x::Foo)
    print(io, "Foo=")
    printstyled(io,x.val; color=:yellow)
end

julia>string(Foo(10))
"Foo=10"

And I tired to replace printstyled with Crayons

using Crayons 
struct Foo
       val
end

function Base.show(io::IO, x::Foo)
       print(io, "Foo=", Crayon(forecround=:yellow), x.val)
end
julia>string(Foo(10))
"Foo=\e[33m10"

Is there way for me to make string conversion work as before? without overriding the string method

KristofferC / Crayons.jl

overriding `Base.show` with Crayon act differently than `printstyled` #61