Shabbos: Wrinkled Shirts

2 questions about shirts: 1) is it permitted to put on a wrinkled shirt on Shabbos, since today's shirts are mixed with synthetic threads which cause the wrinkles to disappear as the shirt is worn. 2) Shirts are usually made with extra buttons at the bottom for replacing buttons that might fall off, so is it permissable to go out on Shabbos with a shirt with these extra buttons, or should they be removed before Shabbos?

Shalom!

Thank you for your question!

Regarding your first question:

It is permitted to wear a wrinkled shirt on Shabbos even if there is a chance that some of the wrinkles might smooth themselves out while wearing it. There are a number of reasons for this such as, all shirts have some creases anyways, it is not certain that the wrinkles will be removed while wearing the shirt, the shirt is obviously still wearable even though there are some noticeable wrinkles, and your intention is merely to wear the shirt and not to take out the wrinkles.

Although wearing a wrinkled shirt is not a problem at all, it is worth mentioning that one must not use any anti-wrinkle spray on Shabbos. This is because using such sprays would be a violation of “tikun mana,” actively trying to ‘fix’ something. Indeed, in certain situations, there is even a ban on folding garments to prevent wrinkles as it too is similar to ‘fixing.’

Sources: OC 302:3; Mishna Berura 302:14

Regarding your second question:

You are obviously referring to an area where there is no Eruv or if, for whatever reason, one chooses not to rely on the Eruv. Even where there is no Eruv it is permitted to wear garments with extra buttons sewn onto them, as is common at the bottom of a shirt. Among the reasons we are lenient is because a) the buttons are considered to have no importance and are therefore secondary (“batel”) to the garment and b) the buttons are considered to be an extension of the garment and c) they are sewn in and essentially permanent.

Sources: OC 301:23 and commentaries