Painting the steel bollards that make up the wall would add at least an extra $500m to the cost of the project, according to contracting estimates seen by The Washington Post.
The president’s enthusiasm for painting the wall has ebbed and flowed over the years. He believes that the dark colour will make the wall more forbidding and too hot to touch. Mr Trump is said to favour a matte black because it absorbs more heat.
The military and border officials, who see the black paint as unnecessary — not just because of the cost, but also the long-term maintenance required — believed that they had talked him out of it and omitted it from the original specifications.
The Post reports that the idea resurfaced in a meeting in April, with the president telling his son-in-law and senior adviser, Jared Kushner, to get cost estimates for the paintwork.
The estimates seen by The Post range from $500m for two coats of acrylic paint, up to $3bn for a premium powder coating.
Whichever option is chosen will add significant costs to what is already one of the most expensive infrastructure projects in the country’s history — $15bn has already been appropriated for construction.
The steel bollards that make up the wall are already weather resistant with a lifespan of 30 years.
Painting would not only be costly, but would significantly slow progress. It would involve painting components before erecting them, revisiting completed segments, and working out how to paint the Mexican side of the barrier, given that only a thin strip of land separates the two countries.
The president has promoted progress on the wall as part of his 2020 re-election pitch, promising to complete 500 miles of construction by 2021.
Approximately 175 miles of new wall has been completed so far and Customs and Border Protection hosts video and an interactive map on the progress of the project.