Archive for the ‘Containerboard’ Category

Bake a cake in a box

January 31, 2018

Stan asks,

We have a customer who wants to bake a cake in our corrugated box. We use recycled paper from XXXXXXXXXX Mill in XXXXXXX. We also have a letter of ‘No Objection’ from Health Canada. Do you foresee any problem or restriction on this method of cake preparation?

Assuming you have some type of suitable and accepted barrier coating the only other concern would be heat. I assume that they are planning to bake in a conventional or convection oven. Since cakes typically bake at 350 degrees F you shouldn’t have to worry about the 451 degree combustion point of the paper.

If a microwave oven is to be used then there may be a few concerns about the paper and what comes into direct contact with it. A mass resting against paper in a microwave can cause temperatures to reach a point significant enough to cause scorching and even combustion of the paper. (I’ve ruined enough bags of pop corn to prove this point)

I’m not sure how the AIB may play into this if the products are to ship into the United States.

Let’s toss this one out to the readers and see what knowledge they have to share.

– Ralph

Checking Moisture of Corrugated Sheets

January 31, 2018

Tim asks,

Recently we encountered corrugated sheets with dry liners and medium that created problems converting. Is there a way for us to test sheets for moisture content at our facility? If so, is there a listing of the ranges?

Moisture meters, or moisture analyzers, can be used to test the moisture content of corrugate sheets. There are a number of portable, hand-held models available. (Most look surprisingly like a taser) They are rather inexpensive (ranging from $50 to $600) and a modest range of testers with varying capabilities and features are available in this range. These units provide instant readings of paper moisture content and should meet your needs. If you purchase a meter/analyzer make sure it is suitable for measuring paper. Some of the least expensive models are only for wood or hard materials. Also check the accuracy rating of the device. If it has a .01% or .02% for paper it should do fine. The same devices may have a 1% – 3% accuracy for wood, but that won’t affect testing paper.

6 to 8 percent moisture is the sweet spot for corrugated paperboard. Below 6% and the risk of cracking scores will increase, perhaps significantly depending on the paper. If the moisture content goes above 8% you will start to see a decrease in compression strength. Reports indicate compression strength can decrease as much as 6.5% per every 1% of moisture over 8%.

Now, in your case (simple checking for machineability) moisture meters/analyzers should work fine. However, they are not the most accurate method for checking paperboard moisture. Should you ever need to certify board for food or pharmaceuticals you may want to find a testing facility that can provide results via the oven method.

– Ralph

Decoding Customer’s Specs

January 3, 2018

Richard asks,

I was a given a spec for an RSC with the paper spec’d as:

K7K 230g + 140g + 230g Kraft C/F.

I don’t know how to interpret this. I’ve reached out to our board suppliers, but I thought you may be able to shed some light. I’m assuming this is a standard way to spec board in some other part of the world.

The paperweight is the easiest to decode. To convert the paper weights from grams to #/MSF simply divide the values by 4.88 and round accordingly to match the closest available weight.

Therefore,

  • 230g = 47.13
  • 140g = 28.68

The other parts of the specification may be a code that is specific to the customers operation. The K7K probably denotes Kraft over Kraft liners and not test liner. The 7 is the caliper, 7mm or .177”. The ‘Kraft C/F’ probably denotes Kraft Corrugated Fluting.

However, that’s a lot of ‘probablies’. To be on the safe side I would try to get the customer to confirm the K7K and the C/F.

– Ralph

Yeast & Mold Standard

December 1, 2017

Reul asks,

We recently had a batch of doublewall boxes held at the port because it was mishandled by the shippers and delayed for about two weeks. The dry container van was stored at the Customs Yard. Maybe the two weeks of exposure to cyclic condition, high humidity at night time and occasional rainfall may have resulted in a favorable condition for spore to develop into molds.

Do you know a standard or allowance of presence of yeast/molds in a corrugated box? We have this analysis of 1500 CFU from the swab test conducted on the samples coming from a certain batch of corrugated boxes that we produce.

This has been a concern for us since one of our customers complained the boxes they received had some dusty matter on its surfaces. We sent samples to an independent lab for microbial analysis and it was confirm to have that reading mentioned above. Is this value alarming?

That’s a tough question. We have no threshold count for molds and yeasts. It would not come with the containerboard except where the relative humidity or liquid water is present with the spores. Certainly the conditions you described could have had an impact on the condition of the boxes and the growth of molds if spores were present. Depending on what the contents are and what the end user environment is these conditions could very well be unacceptable.

— Ralph