is there only limited amount of upgrade materials?

[karkied]

it seem like mcduff sells infinite amount of large titanit shard, but other than that, i havent seen any other unlimited amount of upgrade material merchant.

i mean, im not even halfway through the game, but if there are upgrade materials thats limited then i would like to know.

...mainly because my favorite armorset requires twinkling titanite.

[HypetheKomodo]

You'll come across a vendor who slowly sells more and more kinds of upgrade materials.

You'll end up finding a lot of the materials you'll need, and you can buy the rest later.

[Shironagi]

You can get up to Titanite Chunks as infinite buyables but only near the very end of the game, Slabs, Twinkling titanite and Dragon bones are all finite resources albeit a large pool. Slabs are best obtained via the Belbro covenent as it's an occaisonal reward, Twinkling and Dragon bones are much harder to get.

[perico2palotes]

At first you might think such titanites are hard to come by, but all of them can be obtained easily in infinite amounts. If you walk alongside the coastal line of Majula you'll find this stone where you can pray to join the Covenant of Champions. This covenant makes all trash mobs respawnable after resting at the appropriate bonfire. You might want to switch out of CoC once you're done farming though - CoC makes the game a lot harder.
There are certain trash mobs whose loot tables include twinkling titanites, petrified dragon bones, and titanite slabs. All other titanite types will be available to buy with unlimited supply once you meet a certain NPC.
If you do farm mobs for titanite you'll get truckloads of souls too, so if soul memory is of any concern to you you might want to buy a certain Agape ring from Straid of Olaphis in Lost Bastille. He's the petrified dude near the bonfire on top of the prison cells, close to Sinner's Rise entrance.

[Chronusaur]

The various upgrade and infusing materials are dropped by certain types of enemies. if you wanna know which ones are dropped by what, look it up on the fextralife wiki.