713.17 Materials not attachable for debts of purchaser.—Whenever materials have been furnished to improve real property and payment therefor has not been made or waived, such materials shall not be subject to attachment, execution, or other legal process to enforce any debt due by the purchaser of such materials, except a debt due for the purchase price thereof, so long as in good faith the same are about to be applied to improve the real property; but if the owner has made payment for materials furnished and the materialman has not received payment therefor, such materials shall not be subject to attachment, execution, or other legal process to enforce the debt due for the purchase price.