I have design improvement to the rubber glove for restaurants that work with gloves in front of the customer. It will reduce the cost significantly on production and material. Can I make it in the public domain and start production right away less then the cost of patenting etc.?
You question is a bit confusing, but I'll try to answer my interpretation. If you make an improvement to an existing patented device, you could potentially obtain a patent on the improvement, but if the existing patent has yet to expire, you can not produce the product without obtaining a license (assuming your product is covered by its claims). For any manufacturer, it is a good idea to perform a freedom-to-operate search to assure yourself that no relevant active patents exist. If there are no active patents, then you can go ahead and produce the improved product without a patent, but then nothing stops your competitors from copying your improvement and selling functionally identical products. In some cases, the improvement might be in the manufacturing process and not obvious in the product sold. In that case, a very common tactic is to keep the improvement as a trade secret. In any case I'm not sure what you mean with the term public domain. Selling a product counts as public disclosure and should preempt anyone else from being able to patent the improvement.