Friday, December 5, 2008

Mylar Bag Sealing Using a Clothes Iron

Mylar bags and 5 gallon plastic buckets are meant for each other and is the simple, cost effective and proper way to safely store your bulk foods for the long term. In a nut shell simply place a Mylar bag into the 5 gallon bucket, add your food and the appropriate number of oxygen absorbers, then heat seal the Mylar bag closed and snap on the bucket lid. It’s really that simple!
The only potential problem we face when doing this procedure at home without purchasing sophisticated commercial heat sealing equipment is, how do we create the perfect seal needed for this method to be effective?

Typically a 2x4 type piece of wood would be used as an anvil for the heat sealing surface, place the open end of the bag over the 2x4 and use a household clothes iron to apply the heat needed to bond the open end of the Mylar bag together. This 2x4 method can be a hit or miss approach due to the large surface area we are trying to create a seal with due to the number of square inches of area to heat and seal with this size of an anvil board. It’s nearly impossible to keep the Mylar bag sealing area wrinkle free and at the same time applying even heat and pressure over that broad of a surface to get a proper bag seal.

The solution is similar in that I still use the household iron but use a different anvil board configuration for the heat sealing surface.

I used a 1x6x22 inch long board (although the width can be 3-4 inches) and attached by gluing a piece of molding trim that has a half round contour on it and secured at the lengthwise edge of the main board. It is very important that there are no nail heads, holes or other imperfections on the top of the ½ round molding trim. The half round molding now acts as the anvil and concentrates the heat and pressure of the iron on that crown of the molding which will produce about a 1/8 inch wide seal ensuring a proper bonding seal.

The photo immediately following the first photo of “all the items you need” is a close up end view of the anvil board with the trim molding attached to show you what I’ve done. The molding can be any style molding as long as it has a radius feature or a crown to concentrate the irons sealing heat and pressure.

The items you need to long term seal bulk food in 5 gallon buckets are a; bucket, lid with gasket, 4-500cc oxygen absorbers, 20"x30"x5mil Mylar bag, clothes iron, anvil sealing board and a bag of rice, beans, wheat, pasta or what ever you want to store.

Step #1Sealing Procedure:
Open the Mylar bag and place it into the bucket. Using your hands spread the bag open to form fit the bag the best you can to the bottom and walls of the bucket. This will reduce dead air space, bag strain and a possible rupture to the Mylar bag when filling the bucket with the food.

Step #2Add the food to the bucket.
Add the food you are storing into the bag/bucket. Do not fill the bucket to the rim. Try to keep the food about 2 inches below the rim of the bucket. You need this space to fold the excess Mylar bag into and still be able to close the lid.

Add the Oxygen Absorbers, four 500cc absorbers are more than enough for rice, wheat and beans and other small grained foods, and try and equally space them equally as you fill the bucket. As you add the absorbers use your hands and press down on the food to help press the Mylar bag against the bucket walls and bottom to make use of all the bucket volume possible.

1st one on the bottom
2nd one at 1/3 full
3rd one at 2/3 full
4th one on top

Step #3Close the Mylar Bag.
Take the open end of the Mylar bag and grasp the bag edge seams and spread them apart to close the bag. Take your time doing this. You don’t want any wrinkles in this area, just a very smooth bag surface to surface for the sealing operation.

Step #4Place the anvil board on top of the bucket.

Close up end view of the anvil board showing
the trim molding attached

Step #5Grasping the two edge seams of the Mylar bag stretch it apart and fold the open end of the Mylar bag over the half round anvil and try to keep it wrinkle free.

Step #6Now place the pre-heated iron (use the cotton setting) on top of the Mylar directly above the half round molding and apply about the same amount of pressure on the iron as if you were ironing a pair of pants. Slowly slide the heated iron with medium speed, about a 3-4 second count beginning to end across the top of the half round using constant pressure on the iron. I go over the same seal bead three times with the heated iron.

Step #7I repeat the seal 4 times on the Mylar bag, spacing each seal bead about a half inch apart. It almost guarantees that one of those 4 seals is the perfect seal you are trying to achieve for safe long term food storage.

The four seal beads should look like this.

Step #8Fold the excess Mylar into the bucket and install the lid.
This is why you must not fill the bucket to the rim with food. By leaving about 2 inches you will have 1½inches of space for the excess Mylar bag to fit in and the ½ inch the bucket lid needs to be seated.

Step #9Loosely set the lid on the bucket and wait 2-3 days to give the oxygen absorbers time to consume all the oxygen from inside the sealed bag. As the oxygen is consumed the bag will shrink down to a snug fit around the food packed. If you seal the bucket lid before the shrinking occurs the bucket side walls can be sucked in and distort the round shape.

After the 2-3 days has passed use a 4 lb. mallet (shown in the photo below) or a hammer with a block of wood placed on top of the rim to prevent hammer damage to the lid and strike firmly to dive the lid down until it snaps closed and sealed.

I use a “Dead-Blow” 4 lb. mallet to drive the lid on.
It works great!

Step #10Labeling the bucket.
Labeling the bucket with the contents is very important. After all it may be 5-10 years or longer before you need the food inside and with 10-30 or more buckets accumulated over the years you will never remember what’s in them.

Where to place the label?
The best place I find for the labeling is just above the handle as shown in the photo. By placing the information there the handle will never block the label from view so when the buckets are in storage on the shelving and you take regular inventories of your stock it will make that task easier.

The labeling should be able to tell you the following;The type of bulk food.
The foods manufacturer.
The processing lot number or date. (if a recall you will know if you’re affected)
The actual description of the food.
The month and year you packed it for storage.
The amount by weight of the food inside. (from this you can calculate how many servings of prepared food are in each bucket)

Note; there is a down side to using self adhesive labels. Should you have water damage they may come off or become blurred or unreadable. As a back-up or alternative is to use a Sharpie marking pen and write directly on the bucket, just be sure to print legibly.

My bucket label

Note about the Iron’s Surface Temperatures:
The Mylar material can be melted or sealed by using the “Maximum” heat setting on the iron. This setting will produce a temperature between 300 and 310 degrees.

The typical household iron does not produce an even temperature from the point to the heel of the iron’s heated surface so you need to remember that it is the tip or top 1/3 area that has the highest temperature for sealing and it is that area you need to keep in contact with the Mylar and the anvil board when sealing the bag.


  1. This comment has been removed by the author.

  2. This comment has been removed by a blog administrator.