Unwanted vertical separation between tcolorboxes

Question

I am trying to prepare printer labels for the spine of ring binders. The text is designed to be printed on label paper sheets with A4 format, having top and bottom margins of 26.5mm and left/right margins of 9mm.

The format of the labels is 61mm by 192mm, there are 4 of them on the sheet, without any separation between them.

I use the tcolorbox environment as a 'frame' for the labels and and perhaps my idea is to naive, but I just wrote four of such environments in a row with nobeforeafter setting for each (well, using \tcbset command).

Even with \parskip set to 0pt there is small spacing between the boxes of about 1mm, which would lead to a shift of the content consecutively, and the 4th box appears on the next page. Reducing the bottom margin is not an option, of course. I believe, that \parskip is of no use here anyway.

I am pretty sure, that the content of the boxes has no influence on the spacing, as long as the height is not too large, which does not seem to be the case here.

How can I reduce the space between those colorboxes to a effectively 'zero' value, resulting in no shift when printed?

Note

I checked the margins etc. after print out, they are correct!

Even if there might be other solution for such label printing, I would like to have some solution to reduce the spacing between the boxes (Ok, it might be a very trivial solution.)

This is the code I tried so far

\documentclass[12pt,paper=a4]{article}

\usepackage[lmargin=0.9cm,rmargin=0.9cm,tmargin=26.5mm,bmargin=26.5mm,showframe=true,a4paper]{geometry}
\usepackage{tcolorbox}
\usepackage{lmodern}


\begin{document}
\setlength{\parindent}{0pt}%
\setlength{\parskip}{0pt}%
\pagestyle{empty}%

\fontsize{80}{96}\selectfont 
\tcbset{height=61mm,nobeforeafter,top=2cm}
\begin{tcolorbox}%
\textbf{\LaTeX}%
\end{tcolorbox}
\begin{tcolorbox}%
\textbf{is}%
\end{tcolorbox}
\begin{tcolorbox}%
\textbf{very}%
\end{tcolorbox}
\begin{tcolorbox}%
\textbf{sophisticated}%
\end{tcolorbox}

\end{document}

I looked into other 'similar' questions here, none of them seems to be connected to this problem

• Vertical alignment of "nobeforeafter" tcolorbox
• Tcolorbox in footer with nobeforeafter adds space to other elements in footer
• tcolorbox doesn't print offset correctly?
• too much space between two environment create with tcolorbox

Note

Here is the result with some features of the tcolorbox package and the solutions by Gonzalo Medina and egreg together with the comment by Thomas F. Sturm.

Answer 1

You need to cancel the natural \lineskip:

\documentclass[12pt,paper=a4]{scrartcl}

\usepackage[lmargin=0.9cm,rmargin=0.9cm,tmargin=26.5mm,bmargin=26.5mm,showframe=true,a4paper]{geometry}
\usepackage{tcolorbox}
\usepackage{lmodern}


\begin{document}
\setlength{\parindent}{0pt}%
\setlength{\parskip}{0pt}%
\pagestyle{empty}%

\fontsize{80}{96}\selectfont 
\offinterlineskip
\tcbset{height=61mm,nobeforeafter,top=2cm}
\begin{tcolorbox}%
\textbf{\LaTeX}%
\end{tcolorbox}
\begin{tcolorbox}%
\textbf{is}%
\end{tcolorbox}
\begin{tcolorbox}%
\textbf{very}%
\end{tcolorbox}
\begin{tcolorbox}%
\textbf{sophisticated}%
\end{tcolorbox}

\end{document}

In the above example, \offinterlineskip will have effect from the point where it was issued on. To have suppress the \lineskip in a more controlled way, one could use the after key in with

after=\par\nointerlineskip

as Thomas F. Sturm suggested in his comment.

Answer 2

The spacing is due to \lineskip; the usual setting of \parskip is to have zero natural width, so it can add vertical space only when \flushbottom is set, because it has a stretch component of 1pt. In this case, you should set it to zero and also set \lineskip to zero, but in a group to avoid the setting going on forever.

\documentclass[12pt,paper=a4]{scrartcl}

\usepackage[lmargin=0.9cm,rmargin=0.9cm,tmargin=26.5mm,bmargin=26.5mm,showframe=true,a4paper]{geometry}
\usepackage{tcolorbox}
\usepackage{lmodern}


\begin{document}

\begingroup
\setlength{\parindent}{0pt}
\setlength{\parskip}{0pt}
\setlength{\lineskip}{0pt}

\fontsize{80}{96}\selectfont 
\tcbset{height=61mm,nobeforeafter,top=2cm}
\begin{tcolorbox}
\textbf{\LaTeX}
\end{tcolorbox}
\begin{tcolorbox}
\textbf{is}
\end{tcolorbox}
\begin{tcolorbox}
\textbf{very}
\end{tcolorbox}
\begin{tcolorbox}
\textbf{sophisticated}
\end{tcolorbox}

\endgroup % the empty line is needed

\end{document}

Why is \lineskip intervening? Because each line has height plus depth larger than \baselineskip, so the difference between “depth of the line above plus height of the line below” and \baselineskip is larger than \lineskiplimit (usually 0pt), hence TeX inserts \lineskip glue, thinking that the lines are too near to each other.

A different solution, from a comment by Thomas F. Sturm, is adding after=\par\nointerlineskip to the options to tcolorbox:

\tcbset{height=61mm,top=2cm,after=\par\nointerlineskip,before={}}