Paint firms AkzoNobel and Jotun have donated tens of thousands of pounds worth of specialist coatings to help preserve the 83-year-old vessel.
TS Queen Mary was built by Denny of Dumbarton and spent more than 40 years taking passengers “doon the watter” from Glasgow to Dunoon, Rothesay, Millport and Arran on the Clyde.
The ship has been rescued from dereliction in Essex by the Friends of TS Queen Mary, which raised Â£300,000 to buy and bring her back to the Clyde in May.
A Â£2 million fundraising campaign for the vessel’s restoration was launched by charity patron Robbie Coltrane the following month.
It intends to turn the ship into an exhibition and arts and culture venue.
Queen Mary was moved to dry dock last week for a full inspection prior to her hull being stripped down and repainted.
Charity trustee Iain Sim said: “The paint on any ship serves more than just a cosmetic purpose.
“It is essential in order to protect the vessel from salt water and the weather Scotland is known for all year round.
“AkzoNobel and Jotun bring with them centuries of expertise, giving us absolute confidence the meticulous and delicate job of repainting the Queen Mary will be handled with the utmost care and attention.”
AkzoNobel Marine Coatings spokesman Jim McKinlay said: “We are proud to support the charity behind the restoration of this iconic Scottish vessel.
“By providing sustainable, high-performance coatings, we are sure Queen Mary can continue to be enjoyed and admired, in all her glory, for many more years to come.”
Evan McGrath, of Jotun, said: “Supporting the restoration of this famous turbine steamship is a fantastic opportunity for us and we are only too pleased to help.”
The vessel, whose name was changed to Queen Mary II after the Cunard liner was launched, is on the UK’s National Historic Fleet register.
The more famous liner has been a hotel and visitor attraction in Long Beach, California, since 1967.
TS Queen Mary was latterly operated on the Clyde by Caledonian MacBrayne until being withdrawn in 1977 and moved to London after plans to plans to use her as a maritime museum were scrapped on financial grounds.
The vessel served as a bar and restaurant beside Waterloo Bridge from 1998 to 2009.
She was sold to a French firm for conversion to a hotel and towed down the Thames to Tilbury but the plans fell through.