He is known for refining damascening, a technique that involves inlaying gold, silver, and other metals into an iron surface, creating an intricate decorative effect.

Taking over his father's armaments factory, he adapted it to make art pieces which he exhibited at international fairs, winning multiple awards.

His notable works include the altar for the Sanctuary of St. Ignatius at Loyola, the Fonthill Casket (an iron cassone with intricate decoration inside and out), and a monumental sarcophagus for the Prime Minister of Spain, Juan Prim.

[4] Plácido contacted the English art collector Alfred Morrison, heir to a textile fortune, whom he had met at the 1862 International Exhibition in South Kensington, London.

[10] Zuloaga was skilled in all the techniques used by metalworkers of his time, including forging, relief chiselling, engraving, drawing and enamelling.

[10] In order to create his most ambitious works in a reasonable time, he led a team of specialist artisans who carried out his designs, each object being produced by eight to twelve individuals.

[11] Included in these are the Fonthill Casket, a 201-centimetre-wide (79 in) iron cassone with gold and silver damascening, decorated with white enamel ornament in black.

[8] Also commissioned by Morrison are a pair of amphora-shaped urns, 108 centimetres (43 in) high, from 1878 whose style imitated the medieval Alhambra vases.

[14] Covered in intricate Hispano-Arabic decoration, possibly drawn from contemporary engravings of a specific Alhambra vase, these were exhibited in Paris before delivery to Morrison.

[14] A writing desk dated 1884–1885 has 44 drawers in a wooden case, each with enamelled floral patterns and a damascened metal button-pull.

[15] A 47.3-centimetre-high (18.6 in) iron shrine dated 1880 recalls Gothic architecture in its overall shape, but the intricate damascened decoration is more suggestive of Art Nouveau.

[25] "Plácido Zuloaga: Spanish Treasures from The Khalili Collection" was held at the Victoria and Albert Museum in London from May 1997 to January 1998.

"Metal Magic: Spanish Treasures from the Khalili Collection" was exhibited from November 2011 to April 2012 at the Auberge de Provence in Malta.

[25] With his first wife Lucía Zamora y Zabaleta, he had ten children, five of whom survived to adulthood, including Ignacio Zuloaga, who would become a noted painter.