"Stamps aren't perfect at transferring with high fidelity, so we'd have to be careful about using them."

"Hmm. Yes. That makes sense. I wonder if a stencil would work better."

"Maybe - if I understand correctly we'd be able to abort without finishing if we made a mistake?"

"Yes. But--how much fine control do you have over what you're changing? Do you even need to physically apply dye, couldn't you just change exactly and only what the stencil showed?"

"Yes, I could, but anybody could use a stamp or a drawing-type stencil, right? You could have mass-producible magic."

"Ooh, hm. That is a truly excellent point. I'm a little concerned by the possibility that people would be careless and set things on fire but there have to be ways to mitigate that risk without scrapping the project entirely." She takes out her notebook to write this down.

"You were saying that silk being flame-retardant would help, there are materials less burnable than silk probably?"

"My concern isn't that it can't be done safely, my concern is that people won't take the safety precautions seriously."

"Yeah, that's fair, but people handle other fire hazards like matches and mostly manage not to burn down their houses. They probably have invented fire extinguishers here. How much fire are we talking about?"

"Depends on how many Correspondence sigils and how large and how careless. If you have good reflexes and a bucket of sand handy you could practice them on regular sheets of writing paper all day from a starting point of total lack of understanding and not end with worse than a singed sleeve and a lightly charred desk. But that's if you have to personally physically draw each one, if you have a stamp and are mishandling it you could potentially end up with nothing visibly wrong right up until the house burns down." 

"Why, if it's the same size, same reflexes, same bucket?"

"Because if it's almost right, but it's not almost right because you have any idea what you're doing, then the almosts can build up until something snaps and you won't realize it's coming. And by that point you'll have a lot more sigils than the person drawing them does when his paper catches fire." 

"Oh, I was imagining it'd start burning as soon as you drew it wrong."

Headshake. "Sometimes everything seems fine until enough sigils are put in the same space." 

"Maybe they could have computers check them as they come off a printer for errors? Computers can do stuff like that."

"That would solve the problem of a faulty stamp but not the problem of a damaged one. --I'm not trying to argue against this, I really think it's a great idea, but I want to think about how to make it as safe as possible first."

"What if just finished stamped products were sold?"

"That could work. I'd still be concerned about people deciding it was a great idea to try to draw the sigils themselves--people know not to drop matches on things, they don't know not to do this--but. Less dangerous."

"And they'd be drawing them by hand and the products could ship with warnings. Does the sigil even have to be visible?"

"--No, you could absolutely put it between layers of something." 

"There you go then! That's proof against casual copying and if someone takes it apart they probably take everything apart and we cannot save them because many household objects in a high tech society are unwise to take apart without knowing what you're doing."

"I'd believe it. We have enough electricity in 1898 that I can tell that's what a lot of this tech stuff runs on and also my brother has told me what the stuff can do to careless people who stick fingers where they shouldn't. My brother is a student at the University," she explains. 

"Oh cool, I didn't remember when electricity became common. Yeah, it's all over the place, it's risky, it can power things that are also risky in separate ways, people in industrial societies become used to purchasing objects they shouldn't immerse in water or stick their fingers inside, there might be a learning curve for 'don't crack it in half and copy the pretty writing' but it can get cut down."

"I wouldn't call it common exactly but it's around."

"Around, then. By 2006 it's ubiquitous. I should actually check if they use a kind of outlet here I can use to charge my phone; I've been avoiding using it because it won't last long if I turn it on."