Why Do Some Plastic Crankbaits Swell From Heat?

[mark poulson]

Having had lots of plastic cranks swell in the summer heat, I'd like to know why it happens?

My Japanese cranks don't, and all of my first generation red eye shads did, as well as lots of my DD22s.

Is there a more expensive plastic that isn't as affected by heat?

 

[bass100]

I have never had a crank swell on me but I live in PA.  I did a little bit of research and found that it can happen to any plastic crank.  I think the only solution is to keep them out of extreme heat.  Hot air expands and it has to go somewhere.

[Chuck Young]

One reason could be the greenhouse effect. Transparent tackle holders become a greenhouse. I imagine a hollow lure - even with paint on it - will collect and store heat. The closer to a globe the shape of the lure is, the more efficiently it stores heat. Keeping trays in tack e bags with the cover closed will help. The table below may help. It shows the temp at which plastics begin to distort. I believe they make lures out of PVC and ABS. ABS would be superior. But if lures are reaching almost 200 degrees, it can probably be prevented. An extra 20 degrees may not make much of a difference. I wish lure suppliers would tell us what they use. It might make a difference who we choose to buy from.

plastic distortion temps

PVC        197.6F

ABS         216.1F

PS           216.5

PE           261F

PP           306F

PC          312.8

Edited May 19, 2016 by Chuck Young

[bass100]

I believe those are distortion temps with just heat, once you add the pressure from the expanding hot air I am sure the baits would distort at a much lower temp.

[Cougarftd]

I have seen a lot of the old wiggle warts do that

[SW Lures]

Take a infrared laser thermometer gun and put a crank into the sun light you well be very surprised at the temperature that is created.

As far as pressure goes, this can get extreme. Trust me in my job I have seen extreme increase pressure from sunlight, radiation. And also rapid decrease pressure from rain, cloud cover when the vessel/plastic crank has been exposed to sunlight.

I've seen polyethylene (plastic) pipe over 100° above ambient temperatures. We can not test when pipe is exsposed to sunlight or we have to cover the pipe (any pipe) from the sun. It creates erratic pressure changes and will make a test fail.

So IMO it's both of these issues. My suggestion is to do what has already been mention cover them when not in use. I have a friend that that's all he does, even a clear tackle box. If we ever have and sun and warm weather I could find what temperatures are created and maybe what pressures are created.

For the ones that do not it could be the construction design, another could be not being equal condition to all that we are chatting about. To many scenarios to really know.

Take Care,

Dale

Edited May 20, 2016 by DaleSW

[CNC Molds N Stuff]

I wonder if any of it has to do with the humidity at the time the halves are joined.  As we know water vapor expands a LOT when temperature rise. 

[Chuck Young]

I believe those are distortion temps with just heat, once you add the pressure from the expanding hot air I am sure the baits would distort at a much lower temp.

Those distortion temps are under a 1 lb weight. But you make a good point. Air pressure could exert a lot of pressure.

[fishon-son]

I HAVE A BABY 1- THAT THE PAINT CRACKED ALL OVER AND WHEN I LOOKED CLOSER THE BAIT HAD SWELLED RIGHT UP...SENT IT TO MANNS FOR A 5 IN RETURN SOME STICKERS AND A PATCH..SO I GUESS IT CAN HAPPEN...    dam caps

[SW Lures]

Interesting Bob, no matter what we do unless vacuuming or injecting a dryer gas, our atmosphere has moisture in it. During the forming of the bait it could be trapped inside.

So if here in the south during the summer months, there would be more moisture trapped then in let's say Arizona during the same time.

Nice Bob,

Dale

Edited May 20, 2016 by DaleSW

[Chuck Young]

PVC is injected at 350f  and abs at 400f minimum. But the halves cool completely before assembly. I wonder if there is any climate control in the assembly area?

[BobP]

I'm sure there are differences among the different kinds of plastics used and you'll never be able to predict which ones will swell up, which won't. You also have a mechanical effect. It takes much less pressure to deform a curved body from the inside the curve than it does from outside. That is why chicks can break out of their eggs so easily.

[SW Lures]

No matter what it's a interesting topic. Some very good opinions.

Dale

[Travis]

Very interesting topic and one that has a lot of information behind. Several answers are hitting on some of the issues.  

 

Your question falls into the material science end.  A few topics that are pertinent if you really want to get to the reasons are understanding glass transition temperatures of polymers, coefficient of thermal expansion, heat deflection temperatures, creep, and then chuck in refresher or pressure, temperature, volume.   Design also ends up playing an important role in controlling or reducing the effects that are related to these topics.

 

Take home message don't  leave cranks in direct sunlight.  

 

Controlled environment? Companies have a long history of using China manufacturing for their rigorous standards and.....no it isn't controlled they can make them for a penny a piece.     

[wildturkey]

I too have had DD22's "explode" into fragments in a really hot storage area. I think it must be the air expanding in the bait. Wish I would have known earlier that is was possible for that to happen, I would not have stored them in that type of temperature.

[mark poulson]

I've never had a crankbait that was on the deck on a hot day swell.

All my swollen baits happened when they were in a plano box in a tackle compartment behind the passenger seat in my boat.  I kept it covered on my driveway in Los Angeles, and I know it got hot under that cover in the summer.  I'm just perplexed because in the same plano box, some baits swelled, and others didn't.  Even baits of the same model had some swell and some not.

I remember reading that Aaron Martens insulates all the lids on his boat compartments.  Maybe that's the answer.

My boat is garaged now, so I don't have to worry about it anymore.  It never gets that hot now.

I test fished some of the swollen Red Eye Shads, and they didn't swim right anymore.

But the DD22 baits that swelled still fish fine, even though they look awful.

[CNC Molds N Stuff]

You know its funny.  When I was first trying to get more serious about bass fishing I recall guys on R.O.F.B talking about deliberately swelling Bandit cranks by tossing them in hot water on the stove.  I guess it made them into some kind of magic hunting fish stalker.  I never had the nerve to try it.  Can't say I ever owned any Bandit cranks either.  I have fished some swollen cranks, and most did s__k, but a few seemed to have an interesting wobbling hunting action.  I honestly do not recall which ones.  If I had caught fish on them I bet I would remember though. 

[Chuck Young]

Very interesting topic and one that has a lot of information behind. Several answers are hitting on some of the issues.  

 

Your question falls into the material science end.  A few topics that are pertinent if you really want to get to the reasons are understanding glass transition temperatures of polymers, coefficient of thermal expansion, heat deflection temperatures, creep, and then chuck in refresher or pressure, temperature, volume.   Design also ends up playing an important role in controlling or reducing the effects that are related to these topics.

 

Take home message don't  leave cranks in direct sunlight.  

 

Controlled environment? Companies have a long history of using China manufacturing for their rigorous standards and.....no it isn't controlled they can make them for a penny a piece.     

They don't call 'em sweatshops for nothin'. I was hoping to hear from some of the cage guys here in the US. Climate control would give us one more reason to support their business.

Edited May 20, 2016 by Chuck Young

[DingerBaits]

I have had real Lucky Craft 1.5's and 2.5's blow up on me due to high heat and being in the sun. The way I look at it is the bait is a sealed chamber with air. As air gets hot it expands and needs some where to go. With the plastic also being hot it can only expand to a certain size before the seams burst. 

[RayburnGuy]

Has anyone checked the wall thickness of the baits that are blowing up? If they are thinner they could be significantly weaker than baits with thicker walls.

 

Ben

[Travis]

Wall thickness can play a role and is one of the reason good designs and control of manufacturing specks is important.     The material construction/purity profile of the polymer (as it decreases the glass transition temperature) and thus affects heat deflection.   "Bad" batches due to plastisizer issues also can compound the issue.  

 

The important thing to realize is the only control we have against this issue is to keep baits stored properly.  

[SW Lures]

Since I have never had this issue, it must be the way I handle my baits. When I was young I had to keep what I had together and protected. Since it was a one time shot at getting a lure or buying that lure over and over again as I saved my money.

I kept the lures in the box when not in use, because most of time my fishing was from a pier. Till I was given an old boat with oars. The box was kept in a cool area or I should say a shaded area, my bed room when not in use.

The habit has continued as I got older. I still have whats left of (lost by fishin) my lures. One that I have as a show case piece is a jitterbug lure. Old, battle worn but not distorted. I believe that this is my earliest plastic body. That was my first I think. Caught a lot of fish, but was put away in time. Still was carried around for many years, fished now and again. New baits just makes you think that they are better, I guess. Keep them away from concealed storage areas that can get hot from motors, etc. Control the environment.

So yes I agree with Travis in a long winded way,

Dale.

Edited May 21, 2016 by DaleSW

[Mr.t]

I had red eye shad swell in a Plano box in a boat compartment. I contacted strike king about the issue they told me that they believed that the glue used to hold the the two halves together when expose to heat created a gas that expands causing the bait to swell. I was told by strike king to send the baits to them and they would make it right. I also had various other brands in the same box with no issues,even some other redeye shads that were unaffected. They recommended keeping the baits in storage out of direct sunlight to help prevent lures from swelling. Maybe manufacturers will a dress this problem.

[tendelta]

I have also baits swell and split and "all the baits had a foam inner core" with the foam seeming to have expanded splitting the hard plastic outer bait shell, only happens when the tempature is high 90 or above, check to see if foam filed; as heated the chemical composition produce a great internal air pressure strong enough to rupture the outer shell.   Reno  

[mark poulson]

All the cranks I've had swell were hollow, without foam.