When packing a rectangular mirror or a picture frame, getting a tight fit in a neatly-fashioned carton is not particularly challenging. But what about when that flat, fragile item has curves and odd corners?

If you’re faced with an unusual item – a pentagon-shaped picture frame, a painting in the shape of a palm tree or something truly amorphous – chances are you’ll end up with a mirror carton that is nowhere near rectangular. Fortunately the items we have to pack tend to be much more agreeable and we can wrangle our cartons into decent right angles.

For mirrors some guys prefer bubble wrap. Others go with paper. Here we’ll wrap our mirror in brown paper and add packing paper for the extra necessary protection. And while packing an odd-shaped mirror like the one pictured isn’t terribly difficult, its proportions do demand a little attention.

Squaring the mirror with the paper and wrapping it from there works, though this packer prefers laying items at an angle – this seems to lend itself to a tighter, more reliable wrap when it’s taping time.

In lieu of bubble wrap’s bulky qualities we can opt for a sheet of foam wrap to get that extra layer of protection for these big, relatively heavy items. Lay it flat on your brown paper and incorporate it right into your wrap job.

Mirror cartons offer a good amount of protection, both on the corners and along the sides. Even on the large and vulnerable front and back faces it can be tough to do any real damage – unless of course you are practicing some real negligence. But it can never hurt to add an extra layer of cardboard over the glass. (Used cardboard works just as well as new in this case.)

Once you’ve wrapped and taped up your mirror it’s time to fashion your carton. Two-piece mirror cartons work well if the dimensions match the item being packed; otherwise using a four-piece carton might serve you better. (The pieces pictured here come with interlocking flaps to hold its shape – but only temporarily, because as soon as you begin filling the inside corner with packing paper it comes apart so you’ll need to have taped it anyway, rendering this snazzy little feature practically useless.)

The following is just one possible set of steps to achieving a tight, square mirror carton. Your preferred techniques may differ. The end result is what matters. (With this in mind, we invite you to look for the one rather egregious mistake in the pictures below.)

Size up your carton by setting it up next to the item you are packing. Then make it a few extra inches longer on each end; you’ll need space for packing paper plus a bit of room to slip the top half of the carton inside this bottom half when the time comes.

Remember the side of this mirror is curved, not flat, so certain areas will bear the brunt of the weight when it is placed on its side. Put extra paper down in these areas. The upper part of the mirror is also not as wide as the bottom so another couple wads of paper will help even it out, which will help keep the mirror and thus the carton straight. ** In some cases you might consider folding up a bit of cardboard for stronger interior support.

Once your item is inside the bottom half of the carton, eliminate most of the extra room on each end by simply pushing the halves together. This helps keep the packing paper lining the ends of the carton in place. Leave a little room, however, for when you slip the remaining parts of the carton over the top and inside the bottom half. You don’t want to force all that packing paper to the bottom – this will negate the protective efforts you’ve made. Plus the unnecessary resistance makes it much more difficult to get your carton to form a tight fit.

Before slipping that third corner over the top you will have lined it with packing paper. You’ll do the same with the fourth and last corner, but putting paper too far along that edge will prevent the carton pieces from fitting together properly.

With all four corners now in place, Push down until you feel you’ve got a tight fit. Just like when loading a truck, the less movement inside the better. A tightly-packed load is a stable load; a solid carton is much less prone to being crushed than a loose one.

Turn your carton on end and push down again, to get a better fit vertically. Put the carton back on its original bottom edge and give it another bit of pressure for good measure. Now we are ready to tape it up.

More than for other types of boxes, a four-piece mirror carton depends on tape for maintaining its shape and strength. Tape has to be pulled hard and wrapped tightly around each corner, edge and side – otherwise the carton will quickly begin to loosen and the security of its contents will be compromised. Develop your own favorite method of taping up your mirror carton; we prefer taping the two places where the mirror carton pieces overlap along its width, plus along the lengthwise overlap, several times around. Check again to make sure the edges and corners are taped securely and your mirror is good to go.

By the way…did you catch the mistake we made? Check out where the top of the mirror is inside our box. Then take a look at the printing on the pieces of carton and think: which way would you assume was up?