A survey of manufacturing shows sales in the sector were down 40% in March compared with March last year.
The Manufacturers and Exporters Association survey shows domestic sales were the hardest hit, falling 46% in the month compared with a 31% drop in export sales.
But firms' expectations of future sales, investment and employment rose sharply.
This mirrors signs in overseas' economies that the worst of the global manufacturing slump may be coming to an end and firms are rebuilding inventories.
Despite this, the numbers employed were down nearly 13% after signs earlier in the year that employment in manufacturing was up.