WASHINGTON — Treasury Secretary Jacob Lew won't win any prizes in penmanship, but his official signature which will go on the nation's currency is at least a slight improvement over the loopy scrawl he had a few months ago.

The Treasury Department unveiled the new signature on Tuesday. It takes the Bureau of Engraving and Printing about 18 weeks to put new engraving plates into production. That means Lew's signature will not show up on the various currency denominations until sometime this fall.

Lew's signature had been so bad that President Barack Obama joked that unless it improved it would "debase our currency."

The new signature is still hard to read but it does represent an improvement from previous signatures that were essentially a series of loops. Lew became Treasury secretary, succeeding Timothy Geithner, on Feb. 28.

While the signatures of Treasury secretaries have been appearing on the currency since 1914, Treasury chose a very modern way to release Lew's signature. They tweeted it.

Treasury spokeswoman Suzanne Elio said that Twitter was chosen "given the interest in the secretary's signature and the attention it has received through social media."