Daniel usually left the physical science to Sam, of course, but Sam wasn't around at the moment. Also she probably would have refused to do it, on the grounds that it was unnecessary contamination of the timeline, but he was pretty sure the timeline was fubar'd anyway at this point, and he'd picked up enough improvisational chemistry from his colleagues at the SGC that he thought he could figure it out on his own.
He supposed a quick'n'dirty job with native materials would have worked well enough, but he knew from his experience on Abydos that it wouldn't be the same, and anyway, it wasn't as if he were short on time. So on their next recruiting expedition, he talked Katep into stopping by Nekhbet's capital at El-Kab for a quick supply raid. It took him almost three months to refine the natron he'd gotten there, with crude equipment and working mostly by the seat of his pants, but eventually he had half a small jar of fine white powder. Which actually didn't look much different from what he'd started with, but at least now he was reasonably confident it would work, and wouldn't kill anybody in the process.
Katep stared down at it with him when he was done. "This must be strong magic indeed that you are making, Daneel, that you need to so purify that which itself purifies."
"It is magic that was shown to me by one who is even higher than the false gods," he answered, without smiling, "that her power might comfort me."
The next biggest difficulty was that the native Egyptians didn't have any metals beyond copper and bronze, and those had entirely the wrong heat conduction properties for what he needed. He solved that problem after a weapons run gone wrong, where they'd ended up having to shoot down two of Ra's high-ranking Jaffa in the desert. They looted the bodies and killed the symbiotes as usual, and Daniel looked down at the stupid-looking beaten aluminum skullcaps they always wore under the helmets, thought for a second, and pulled them off to keep for himself. He washed the bits of brain and blood off, and then spent the next few months by the evening fires beating them into shape with a stone mallet and chisel. After he'd got them flat, he settled on a honeycomb pattern rather than a square grid as the best way to ensure strength and proper heat distribution, and he was certain he was right when Katep leaned over his shoulder one night and said "This is for your magic? Tears of Ra, yes?"
"What?" Daniel said."Oh, yes, Shu and Tefnut and honeybees were all supposed to be born of the tears of Ra, weren't they?" He turned the metal in his hands, watching as his blurry reflection was broken again and again by the angles of the pattern. "Ra will weep, Katep, and not for beauty this time. Don't doubt that."
When they were finished and fit together neatly as crocodile teeth, he bound them each on the end of a broken tent pole and fastened them together with a hinge and latch made of bronze.
The rest of it was easier. He'd hesitated to ask for salt, because the salt they used for cooking on holidays was expensive and traded all the way from Siwa, but Katep reminded him about the cheaper sea salt they used in tanning, which was just as pure. It was also sacred to Seth, the enemy of Ra, which was why it wasn't used in cooking. Seth had been in exile for at least a hundred years, Daniel calculated, but he couldn't help feeling a sense of near-kinship at the thought, and gladly added the salt to his cache of supplies.
He'd known there was no hope of refined sugar, but Katep's nephew eventually found a hive of wild honey, which was shared among the clan. Daniel took the portion that would once have been an offering to Ra, and crystallized it dry enough to granulate, although to be honest plain honey probably would have worked well enough. The same with the wheat flour; he took the coarse stuff the women used and worked it nearly as fine as the refined flour of his homeland. Sha're had taught him to grind flour by hand, his semi-holy status excusing him from the strict gender roles on Abydos the same as it did here. He thought about her, sometimes, as his hands moved in the unchanging rhythms of bread, and Katep's sister-in-law mocked him for doing all that extra work.
He kept putting off the final steps until the time seemed right; flour would keep almost indefinitely in a well-sealed jar in the dry climate, and Katep's tribe travelled with their cows and chickens, so there was always fresh milk and eggs and butter, and other things kept him busy. Eventually, though, the plans for the rebellion began to come to completion. They had men and weapons enough and a strategy that ought to work, and they had come back to the place where it all started, to Gizeh where the three ha'tak perched on the pyramids like angular hats. All that was left to do was wait. And think.
The third night of that, Daniel pulled out his basket of supplies, stirred the ingredients together, poured it into the aluminum molds, and turned the mixture over a low fire to heat. He burned the first few tries, but by the time the moon was well up he'd found the trick of producing fragrant, honeycomb-patterned golden cakes, which he gave, with fresh butter and carob syrup, to the others who had gathered around to watch.
The women exclaimed aloud, that they were so soft and light when he had neither kneaded them nor waited for them to rise. He tried to explain baking soda, "It's the natron I cooked them with that made them rise," but the word for natron was netjer, which was also "god" in their language. So they ate the bread of the gods, for strength and power, before going into to battle against them; and Daniel ate his waffles, and thought about a diner in New York, and not about his team at all.