[Tex/LaTex] Single Thicker vertical line

Question

I have this table and I would like to make two vertical lines thiker than the others. This turns out to be useful to visually divide the columns. Basically my table has 13 columns and I would like to turn 2 of them a bit thicker. I won't show the code for the table because it is really huge and not practical to paste it here. What I'm looking for is probably a keyword to make the vertical line thicker, without messing too much with this already messed-up table :-).

Thanks a lot.

EDIT: I tried with the following command

\newcolumntype{"}{@{\hskip\tabcolsep\vrule width 1pt\hskip\tabcolsep}}

But it creates some spacing between one column and the other. Trying to remove the first \tablecolsep solves the issue (that is no more spacing between the columns), but I get three errors: Package array Error: Illegal pream-token (2.2mm): 'c' used. this probably because I declare the column like this: |"{2.2mm} but it I do not declare the size it messes the whole table up, Missing number, treated as zero. on

    \vrule 
\end{tabularx}

and Illegal unit of measure (pt inserted). on the exact same output as the second error. Sorry if these are stupid mistakes but modifying the command shown doesn't lead me to success.

EDIT2:
By using the "array" package and following what @egreg said, I get the following error: Package array Error: Illegal pream-token (2.2mm):c' used. This is probably because I define the columns like this (wherexis\newcolumntype{x}[1]{>{\centering\hspace{0pt}}b{#1}}`):

|?{2.2mm}
|x{2.2mm}
|x{2.2mm}

and so on.

Answer 1

You could use the ! feature of array:

\documentclass{article}
\usepackage{array}
\newcolumntype{?}{!{\vrule width 1pt}}

\begin{document}
\begin{tabular}{|c?c|c|}
x & 1 & 2 \\
y & 11 & 22 \\
z & 111 & 222
\end{tabular}
\end{document}

I wouldn't use " as a specifier, because it can conflict with babel.

However, my advice is don't use vertical rules at all.

If you want to specify the thickness, change the code into

\newcolumntype{?}[1]{!{\vrule width #1}}

and then you can do

\begin{tabular}{|c?{2mm}c|c|}

for having a thickess of 2mm.