Choosing the Right Encasing

Encasing materials can be divided into 2 main categories:

• Encasings WITHOUT membranes
• Encasings WITH membranes.

Encasings WITH membranes are made of fabrics bonded to an airtight layer of water vapor-permeable urethane. Because the membrane is airtight, not even the smallest dust mite or dust mite allergen particle will pass through. They are most suitable for those who are highly allergic to dust mites.

The superior allergy protection unfortunately comes at a small cost. Compared to encasings without membranes, these encasings may feel slightly less comfortable, may feel warmer, and don't pass moisture as quickly (so heavy perspirers may find them feeling damp). You can, however, compensate for these problems by putting 2 or more layers of bedding over the encasing or by using a mattress pad to absorb excess perspiration.

On the upside, since this material is airtight it will not only keep out dust mites and their allergens. It will also block odors coming from the mattress or pillow.

Please note that our encasings use new materials formulated to be soft and flexible and that do not make the crinkly plastic sound characteristic of older technology membrane encasings. Once fitted and covered with bed sheets most people will not even notice that there is an encasing.

Encasings WITHOUT membranes have a special weave or construction that keeps the pore size so small that dust mites cannot pass through. They feel very much like regular bedding material, but if you look closely you will see that the weave is very fine. Our cotton blend material has a pore size of 4 microns (dust mites are about 100 microns long and can probably squeeze through a pore of 25-50 microns). While this fabric prevents most of the allergens from passing through, some of them may be less than 4 microns in size. Therefore, we recommend this material for those with mild to moderate dust mite allergies. You can increase the effectiveness of encasings by layering. For example, I use two cotton blend encasings on my pillow (with zippers on opposite ends of the pillow).

Encasings, even ones with membranes, will eventually develop a population of dust mites on the outside. Because of this, it is important to wash them regularly. Your bed sheets and pillowcases should be washed every 1-3 weeks.Encasings should be washed every 2-6 weeks. But use your own judgment. Keep a note of how much time passes before your freshly changed sheets start to cause you discomfort and use this to determine the frequency of your washes. Personally, since I'm very allergic, I have to wash and change my bed sheets every week and the encasings every 2-3 weeks.

Fitted vs. Zippered Mattress Encasings

Zippered mattress encasings that completely encase the mattress on all sides are without doubt best at trapping dust mites. However, they can be difficult to fit and remove, especially on larger mattresses. Fitted encasings are constructed much like fitted sheets and are very easy to fit and remove. Since regular washing is essential to overall effectiveness, consider your habits before making a choice. A regularly-washed fitted encasing is going to be more effective in the long run than a zippered encasing that is rarely washed. If you want the best of both worlds, you can also use layering. You can, for example, fit your mattress with a zippered encasing that you wash every few months and on top of that a fitted encasing that you wash every few weeks.