I bought pieces of comics that are drawn with pencil, and I’m afraid that they get blurred. How can I preserve them? Can this be done the same way as with sketches?
Welcome to the community! I don't know if you want to do this, but there's something called "fixative spray". In Walmart for $6 you can buy it, it's so effective, you can even edit after spraying. Just let it rest after 1 hour and you'll be fine! That's the solution! the substitute is hairspray, that's a cheaper option, but you won't be able to edit again, just with the fixative. Hope this helps!
There are a number of ways to preserve pencil drawings. This question is explicit in distinguishing that the drawings were purchased, which introduces another consideration.
A common way to preserve pencil drawings is with a fixative. How can I protect my pencil & charcoal drawings once complete? goes into recommendations and discussion on that approach. A fixative works to protect it, but it modifies the surface, and can change the appearance a little. For acquired works, the fixative would be something the original artist did not apply, and would be an alteration of the work.
If you just want to keep the work for its value to you, protect it any way you like. But if investment/resale value is a consideration, or it's a historical work, your applying a fixative to it could seriously degrade its value.
In this case, a better way to preserve it is to either store it in acid-free, archival quality flat files between layers of glassine paper, or have it professionally framed behind (UV-resistant) glass so it can be displayed and enjoyed.
For completeness, plastic sleeves were also suggested as a means of protection, but Allison C advised that smudging can result.
Mylar sleeves for storage are the most common way comics collectors protect original art, being the sturdiest and least likely to cause chemical damage to the paper. Mylar and acid-free cardboard are pretty much your first line of defense with anything comics-related.
I've attended San Diego Comic-Con for 40 years, and the majority of the dealers I've seen there over the decades display/store/ship vintage original art (usually ink over pencil or blue lines on Bristol Board) in mylar sleeves.
Uninked pencil art is also displayed this way if it's not framed or boxed, but I've more often seen that in the poly sleeves of artist's portfolios, being sold by the artist themselves, and that's far less suitable storage for any art.
not sure if that is the best option, but on dry chalk paints I use common/regular hair lack in rattle can.
It does fix the last chalk layer enough, dries fast enough, and do not smell that much as synthetic lack I use for car repairs etc.
As it dry really fast the next chalk layer can be made within seconds. However repairs to previous layers are a bit hard. Use higher weight, stiffer paper, like those for acrylic painting, and spray very lightly, no puddles of lack as it would warp the paper.