question: How come other powders dissolve okay in cold water while others don't? (e.g.: Coffee Creamer vs. Powdered Juice)
comment: Short: Like dissolves like. To dissolve something the liquid has to get a long with the substance you want to mix in it. This is because to mix together enough to dissolve, they have to be broken down to their individual parts. Longer: When a substance dissolves in a liquid e.g. water, it needs to basically separate the substance into its tiny parts. For instance, salt dissolves exceptionally well in water, whilst sand does not. This is because water is what is called bipolar, it basically has charges associated with the sides of the molecule - positive on one side and negative on the other. When salt (NaCl) dissolves it is able to be split into its two parts, a positive sodium atom (Na+) and negative chlorine atom (Cl-) by water molecules surrounding them. For sodium, the negative poles of the water molecule face in (opposites attract) to surround the sodium, and vice versa for the chlorine. Non polar substances (has no charges) can't be dissolved by water. On the other hand, oil which is non polar itself would be good at dissolving the substance instead. Temperature can aid dissolving because it adds energy in. This means the molecules travel around faster and therefore collide more frequently. It can also give them enough energy to undergo the separation into their parts if they didn't have enough energy to do so beforehand
passages: While it is relatively easy to apply thick coatings that cure to smooth, texture-free coating, it is not as easy to apply smooth thin films. As the film thickness is reduced, the film becomes more and more orange peeled in texture due to the particle size and glass transition temperature (Tg) of the powder.
   There are very specialized operations where powder coatings of less than 30 micrometres or with a Tg below 40 °C are used in order to produce smooth thin films. One variation of the dry powder coating process, the "Powder Slurry" process, combines the advantages of powder coatings and liquid coatings by dispersing very fine powders of 1–5 micrometre sized particles into water, which then allows very smooth, low film thickness coatings to be produced.
   Section::::Properties of powder coating.
  
  Because powder coating does not have a liquid carrier, it can produce thicker coatings than conventional liquid coatings without running or sagging, and powder coating produces minimal appearance differences between horizontally coated surfaces and vertically coated surfaces. Because no carrier fluid evaporates away, the coating process emits few volatile organic compounds (VOC). Finally, several powder colors can be applied before curing them all together, allowing color blending and bleed special effects in a single layer.
   A random mixture can be obtained if two different free-flowing powders of approximately the same particle size, density and shape are mixed (see figure A). Only primary particles are present in this type of mixture, i.e., the particles are not cohesive and do not cling to one another. The mixing time will determine the quality of the random mixture. However, if powders with particles of different size, density or shape are mixed the segregation can occur. Segregation will cause separation of the powders as, for example, lighter particles will be prone to travel to the top of the mixture whereas heavier particles are kept at the bottom.
   Most powder coatings have a particle size in the range of 2 to 50 μ (Microns), a softening temperature Tg around 80 °C, a melting temperature around 150 °C, and are cured at around 200 °C. for minimum 10 minutes to 15 minutes (exact temperatures and times may depend on the thickness of the item being coated). For such powder coatings, film build-ups of greater than 50 μ (Microns) may be required to obtain an acceptably smooth film. The surface texture which is considered desirable or acceptable depends on the end product. Many manufacturers prefer to have a certain degree of orange peel since it helps to hide metal defects that have occurred during manufacture, and the resulting coating is less prone to showing fingerprints.
   In modern times, powdered milk is usually made by spray drying nonfat skimmed milk, whole milk, buttermilk or whey. Pasteurized milk is first concentrated in an evaporator to approximately 50 percent milk solids. The resulting concentrated milk is then sprayed into a heated chamber where the water almost instantly evaporates, leaving fine particles of powdered milk solids.
   For example, if one were to make tablets from granulated sugar versus powdered sugar, powdered sugar would be difficult to compress into a tablet and granulated sugar would be easy to compress. Powdered sugar’s small particles have poor flow and compression characteristics. These small particles would have to be compressed very slowly for a long period of time to make a worthwhile tablet. Unless the powdered sugar is granulated, it could not efficiently be made into a tablet that has good tablet characteristics such as uniform content or consistent hardness.
   Powdered sugar is available in varying degrees of fineness, most commonly XXX, XXXX, and 10X: the greater the number of Xs, the finer the particles. Finer particles absorb more moisture, which results in caking. Corn starch or tricalcium phosphate is added at 3 to 5% concentration to absorb moisture and to improve flow by reducing friction between sugar crystals. Because of these anticaking agents, it cannot always be used as a substitute for granulated sugar.
  
  Section::::Other varieties.
   Section::::Enteral formulations.
  
  Oral drugs are normally taken as tablets or capsules.
  
  The drug (active substance) itself needs to be soluble in aqueous solution at a controlled rate. Such factors as particle size and crystal form can significantly affect dissolution. Fast dissolution is not always ideal. For example, slow dissolution rates can prolong the duration of action or avoid initial high plasma levels. Treatment of active ingredient by special ways such as spherical crystallization can have some advantages for drug formulation.
  
  Section::::Enteral formulations.:Tablet.
  
  A tablet is usually a compressed preparation that contains:
  
  BULLET::::- 5-10% of the drug (active substance);
   When a thermoset powder is exposed to elevated temperature, it begins to melt, flows out, and then chemically reacts to form a higher molecular weight polymer in a network-like structure. This cure process, called crosslinking, requires a certain temperature for a certain length of time in order to reach full cure and establish the full film properties for which the material was designed. Normally the powders cure at 200 °C (390 °F) for 10 minutes. The curing schedule could vary according to the manufacturer's specifications. The application of energy to the product to be cured can be accomplished by convection cure ovens, infrared cure ovens, or by laser curing process. The latter demonstrates significant reduction of curing time.
   BULLET::::3. Improved dispersion and/or solubility: Improved dispersion and solubility is sometimes achieved with instantization, in which the solubility of a product allows it to instantly dissolve upon its addition to water. For a powder to be considered instant it should go through wettability, sinkability, dispersibility, and solubility within a few seconds. Non-fat dry milk and high quality protein powders are good examples of instant powders.
  
  BULLET::::4. Optimized bulk density: Consistent bulk density is important in accurate and consistent filling of packaging.
  
  BULLET::::5. Improved product characteristics
   BULLET::::4. A wide range of speciality effects are easily accomplished using powder coatings that would be impossible to achieve with other coating processes.
  
  BULLET::::5. Curing time is significantly faster with powder coating than with liquid coating.
  
  Section::::Types of powder coating.
   Although concentration criteria is a useful rule of thumb when predicting amenability to gravity concentration, factors such as particle shape and relative concentration of heavy and light particles can dramatically affect separation efficiency in practice.
  
  BULLET::::- Classification
  
  There are several methods that make use of the weight or density differences of particles: 
  
  BULLET::::- Heavy media or dense media separation (these include the Sepro Condor DMS, baths, drums, larcodems, dyana whirlpool separators, and dense medium cyclones)
  
  BULLET::::- Shaking tables, such as the Wilfley table
  
  BULLET::::- Spiral separators
  
  BULLET::::- Reflux Classifier
   Because of the above-mentioned instability, the combination of aluminium powder and potassium chlorate is a poor choice for flash powder that is to be stored for more than a very short period. For that reason, it has been largely replaced by the potassium perchlorate mixtures. Chlorate mixes are used when cost is the overriding concern because potassium chlorate is less expensive than perchlorate. It is critically important to exclude sulfur and any acidic components from these mixtures. Sometimes a few percent of bicarbonate or carbonate buffer is added to the mixture to ensure the absence of acidic impurities.
   The clumping behavior of a powder arises because of the molecular Van der Waals force that causes individual grains to cling to one another. This force is present not just in powders, but in sand and gravel, too. However, in such coarse granular materials the weight and the inertia of the individual grains are much larger than the very weak Van der Waals forces, and therefore the tiny clinging between grains does not have a dominant effect on the bulk behavior of the material. Only when the grains are very small and lightweight does the Van der Waals force become predominant, causing the material to clump like a powder. The cross-oversize between flow conditions and stick conditions can be determined by simple experimentation.
   Caking properties must be considered when designing and constructing bulk material handling equipment. Powdered substances that need to be stored, and flow smoothly at some time in the future, are often pelletized or made into pills.
  
  Section::::Mechanism.
   In general, for some material property formula_1 (often the elastic modulus), the rule of mixtures states that the overall property in the direction parallel to the fibers may be as high as
  
  where
  
  BULLET::::- formula_3 is the volume fraction of the fibers
  
  BULLET::::- formula_4 is the material property of the fibers
  
  BULLET::::- formula_5 is the material property of the matrix
   Alternatively, the milk can be dried by drum drying. Milk is applied as a thin film to the surface of a heated drum, and the dried milk solids are then scraped off. However, powdered milk made this way tends to have a cooked flavour, due to caramelization caused by greater heat exposure.
  
  Another process is freeze drying, which preserves many nutrients in milk, compared to drum drying.
   BULLET::::- Powdered milk is a manufactured dairy product made by evaporating milk to dryness. In modern times, powdered milk is usually made by spray drying nonfat skimmed milk, whole milk, buttermilk, or whey. Pasteurized milk is first concentrated in an evaporator to around 50% milk solids. The resulting concentrated milk is then sprayed into a heated chamber where the water almost instantly evaporates, leaving fine particles of powdered milk solids.
  
  Section::::Dried foods.:Processed foods.:N.
  
  BULLET::::- Non-dairy creamer is a liquid or granular substance intended to substitute for milk or cream as an additive to coffee or other beverages.
   BULLET::::- In the case of a weak monoacid (here we take acetic acid with p"K" = 4.76) with decreasing total acid concentration , we obtain:
  
  BULLET::::- The calculation in the case of phosphoric acid (which is the most widely used for domestic applications) is more complicated since the concentrations of the four dissociation states corresponding to this acid must be calculated together with [], [], [Ca], [H] and [OH]. The system may be reduced to a seventh degree equation for [H] the numerical solution of which gives
  
  Section::::See also.
  
  BULLET::::- Cuttlebone
  
  BULLET::::- Cuttlefish
  
  BULLET::::- Gesso
  
  BULLET::::- Limescale
  
  BULLET::::- Marble
   The drying method and the heat treatment of the milk as it is processed alters the properties of the milk powder, such as its solubility in cold water, its flavour, and its bulk density.
  
  Section::::Food and health uses.
   Many other powder behaviors are common to all granular materials. These include segregation, stratification, jamming and unjamming, fragility, loss of kinetic energy, frictional shearing, compaction and Reynolds' dilatancy.
  
  Section::::Powder transport.
   In mixtures such as this, the speed of molecule movement is dependent on molecule size and carbohydrate (in this case, maltodextrin) concentration. Water, the smallest molecule in the mixture, is able to move and evaporate fastest. In higher concentration, by decreasing water, water molecules can move much faster. After the film formed it is less permeable to larger molecules than water. By the time the film is completed, water has evaporated enough. This phenomenon is called "selective diffusion."
   BULLET::::- Menthol and camphor, both solids at room temperature, form a eutectic that is a liquid at room temperature in the following proportions: 8:2, 7:3, 6:4, and 5:5. Both substances are common ingredients in pharmacy extemporaneous preparations.
  
  BULLET::::- Minerals may form eutectic mixtures in igneous rocks, giving rise to characteristic intergrowth textures exhibited, for example, by granophyre.
  
  BULLET::::- Some inks are eutectic mixtures, allowing inkjet printers to operate at lower temperatures.
  
  Section::::Other critical points.
  
  Section::::Other critical points.:Eutectoid.
   The dissolution rate is described by the Noyes–Whitney equation:
  
  formula_1
  
  Where:
  
  BULLET::::- formula_2 is the dissolution rate.
  
  BULLET::::- A is the solid's surface area.
  
  BULLET::::- C is the concentration of the solid in the bulk dissolution medium.
  
  BULLET::::- formula_3 is the concentration of the solid in the diffusion layer surrounding the solid.
  
  BULLET::::- D is the diffusion coefficient.
  
  BULLET::::- L is the thickness of the diffusion layer.
  
  As the solution is already in a dissolved state, it does not have to go through a dissolution stage before absorption begins.
  
  Section::::Ionization.
  