The phrase "a string of red" is correct and usable in written English.
It can be used to describe a series or collection of red items, often in a visual or metaphorical context.
Example: "The artist used a string of red to create a striking contrast against the blue background."
Alternatives: "a line of red" or "a series of red".
A string of red lights pops on.
It lost €800m ($950m) in 2013, the biggest in a string of red annual numbers.
Reporters stand behind a string of red velvet ropes, waiting to shove a recorder in the face of a senator departing the floor.
But all the sensors were still doing their jobs, so the bus showed up on Mr. Levandowski's laptop screen as a string of red dots that stretched out as the bus rounded the corner.
Sitting around a table at Radio, a bar in Oakland barely illuminated by red Japanese lanterns and a string of red lights, the band members clearly enjoy one another's company and jokes.
The Pulupaki had just been acquired from Japan by a Tongan shipping company and was making its inaugural run; a string of red, blue and yellow flags waved cheerily from mast to stern.
In the fall we'll begin opening a string of Reds Cafes ["Reds" is the team's nickname], branded family restaurants, which are to spread all across Asia".
A string of Vietnamese flags, red with a yellow star, hangs overhead.
The second change came later, after a string of background checks showed red flags, forcing Mr. Thammineni to revise his policy of offering conditional employment pending the results.
On a memory test, a patient may be able to repeat a string of unrelated words -- red, Oldsmobile, cabbage -- but then fail to recall even one of them 10 minutes later.
A string of semicircular booths in blood-red leather line the corridor leading to the main dining room, where they are repeated on a larger scale in wraparound booths big enough for six diners.
