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I know some of you were organized and your pockets were full of excess money, so you bought all your winter underwear last fall. For those of us who didn't, now is a good time to take advantage of the sales in all those stores that think it is time to clean out the winter apparel and put out the bathing suits.

Keep in mind that the basic principle of staying warm is layering. Trapping dead air next to the body retains body heat. In cold weather you have to find the balance between insulating the body but also allowing for transmission of moisture from next to the skin outward. A wet body will cool 25 times faster than a dry one.

Materials like polyesters actually absorb the liquid moisture into the fiber and through a wicking action spread it across the material so it can evaporate. Polypropylene cannot wick liquid moisture, but instead transfers moisture in the vapor state via different staple lengths within the fiber. Polyester is normally a hydrophobic (water-hating) fiber, with a moisture regain rate of 4 percent. However, it is not as hydrophobic as polypropylene, which has a moisture regain rate of .05 percent. Moisture regain has an adverse effect on vapor moisture transmission because the more moisture a fabric absorbs, the more it expands, creating an even tighter weave that reduces further moisture penetration. Both polyester and polypropylene fibers, however, are much less absorbent than natural fibers like cotton and silk, which regain moisture at rates of 8 percent and 11 percent, respectively. Other factors that effect moisture transportability are the construction of the cloth (its weave) and the weight (thickness) of the material.

Polyester: Polyester is essentially hydrophobic and does not absorb moisture. The polyester used in thermal underwear, however, has been chemically altered to allow it to absorb and then wick liquid moisture. Some coatings, though, only last five washings.

Chemically Finished Polyester: Polyester chemically modified to enhance wicking capabilities by creating a hydrophobic surface while retaining a naturally hydrophobic core. This creates a fabric in which the fibers spread liquid moisture across the surface so that it can dissipate and dry while the fibers' core refuses to absorb moisture.

Capilene: Core remains hydrophobic. Antimicrobial finish added to inhibit the growth of odor-causing bacteria. Retains capabilities for more than 50 washings.Polartek and PolywickChemical finish. Surface absorbs and wicks moisture and the core remains hydrophobic. Retains for 50 washings.

Wintergard: Polyester made up of different fibers to enhance moisture vapor transfer. Two different thickness create passages in which still air can be trapped, increasing the insulation value.

Molecularly Modified Polyester: Does not absorb water, but instead wicks along its surface. Can be destroyed by fabric softeners.

Bio Thermal Underlayers (BTU): Modified polymer that allows the polyester to transport liquid moisture and creates air pockets for optimal insulation.

Skinetics: 100% polyester that has had its molecular weight modified to allow transport of liquid moisture.

Thermax: Hollow-core polyester with a moisture-loving surface and a moisture-hating core. Molecularly modified for easy evaporation. The hollow core increases insulation because the hollow spaces trap more air. It may also trap perspiration and therefore odor.

Untreated Polyester ComFortrel: First polyester capable of transferring moisture without a chemical treatment. Unique formula that feels like cotton.

Fabric Treatments Neutratherm: Latest fabric treatment that claims to store and release thermal energy, adapting to thermal fluctuations at the skin's surface, to prevent perspiration and chilling. Body heat makes the polymer soften and store excess heat normally lost. As the wearer cools down, the polymer hardens releasing the stored heat. The coating also imparts absorbency, abrasion resistance and thermal insulation. Fabric has been proven to remain stable through more than 50 washings.

Polypropylene: Least absorbent of all textile fibers. It cannot wick liquid moisture, but transfers vapor moisture. Polypropylene has a bad reputation for retaining odors. Users have also complained of shrinkage. Only tolerates low heat in dryers.