# What causes a ballpoint to leak ink?



## ossaguy

This might sound like a real rookie question,but can someone explain to me what causes it to happen?

I discovered that one of my ballpoints leaked in my shirt pocket,and it was a new & expensive shirt.Then today I found a cross cartridge had leaked out of the knurled plastic end,and it had never been removed from the kit bag yet.

So I'm asking also for tips on how prevent it from happening.

Thanks for any thoughts!

Steve


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## TonyL

I have experienced the same regardless of the quality/price of the pen (store-bought and now, home-made). I think the reality is that pens leak. I noticed pens leaking more often when I use them to draw long lines - like to line a page with a ruler. This has just been my experience. I don't keep/store pens anywhere leaking would damage something. I hope some has an answer/solution. Otherwise, for me, it is death, taxes, and leaking pens.


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## frank123

Heat can cause this if you are outdoors in hot weather or in a hot work area, particularly with gel ink and click type roller ball inserts such as uni-ball and G2.  I think it thins the ink enough to let is get past the clearance around the ball.


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## 1080Wayne

I think a properly functioning ballpoint requires a balance between three things : ball diameter , nib opening diameter and ink viscosity . Plus or minus manufacturing tolerances will exist for all three . Small ball diameter and/or large nib opening and/or low viscosity will cause a pen to leak . Large ball diameter and/or small nib opening and/or high viscosity will make it difficult to start the pen writing . None of those are in your control . The best manufacturers will have the tightest tolerances and therefore fewer problems of either type . The same arguments apply to leakage from the knurled end .

I would assume that the optimum and designed operating range for a ballpoint would be 70 F plus/minus 10-20 degrees . That will translate into you getting more leaks than someone in Alaska , and they will have more pens that don`t want to write . 

So , store pens and refills at room temperature if possible . Turf leaking refills ,  smudgy refills , refills that don`t want to write and scratchy refills , and you should end up with happy customers .


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## workinforwood

Heat and cold are equal partners in destruction. Most inks are water based these days, heat like sitting in a hot car expands the ink causing pressure inside to push up the top or push the ball out of seat on the bottom. Cold is likely to do even more damage than heat as the ink freezes and expands causing hydraulic pressure which can crack the ink tube or unseat the "cork" on top. It is more likely that your unopened leaking refill was damaged by cold air, as the suppliers are mostly in cold climates, the manufacturers ship in containers overseas and world wide we had one of the coldest winters in decades across the entire globe.


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