Slippery Elm bark for esophagitis and/or gastritis: (per Dr Kathy)
The powder is generally believed to be more effective than capsules. Instructions:
–   Put a cup of powder in 2 cups water and simmer down to 1 cup
–   It will be consistency a bit thicker than salad dressing will just take 3 minutes.
–   Give a few tsp – tablespoons 3 times daily.
–   Give 1 hour before or after any other meds to minimize inactivation of those meds.
–   Can be refrigerated for up to 2 days.
–   Give at room temperature.

I did some research and also found this suggestion:
–   Powder: Mix two cups boiling water to one tablespoon of powder, three times a day.
–   Simmer down to 1 cup.

It does need to be prepared fresh, each time it is to be used. Slippery elm may interfere with the way that other medications or herbal remedies are absorbed by your body. To avoid this, take slippery elm several hours before or after taking other medications. Slippery elm prepared as a poultice coats and protects irritated tissues such as skin or intestinal membranes. The powdered bark has been used in this manner for local application to treat gout, rheumatism, cold sores, wounds, abscesses, ulcers, and toothaches. The tannins present are known to possess astringent actions. It also has been known to draw out toxins, boils, splinters, or other irritants. Powdered bark is incorporated into lozenges to provide demulcent action (soothing to mucous membranes) in the treatment of throat irritation. It also is used for its emollient and antitussive actions, to treat bronchitis and other lung afflictions, and to relieve thirst. When slippery elm preparations are taken internally, they cause reflex stimulation of nerve endings in the GI tract, leading to mucus secretion. This may be the reason they are effective for protection against stomach ulcers, colitis, diverticulitis, gut inflammation, and acidity. Slippery elm also is useful for diarrhea, constipation, hemorrhoids, irritable bowel syndrome, and to expel tapeworms. It also has been used to treat cystitis and urinary inflammations.

Can get slippery elm bark syrup from some health food stores: Roughly 1/4 tsp/15-20 lbs To make the tea: Steep 2 tablespoons of powdered bark in 2 cups of boiling water for about five minutes and allow to cool. Give 1/4-1/2 cups twice daily.  Can mix in with applesauce, etc.

Tea: Pour 2 cups boiling water over 4 g (roughly 2 tablespoons) of powdered bark, then steep for 3 – 5 minutes. Drink 3 times per day. Tincture: 5 mL 3 times per day. Note: Contains alcohol. Capsules: 400 – 500 mg 3 – 4 times daily for 4 – 8 weeks. Take with a full glass of water. Lozenges: follow dosing instructions on label. External application: Mix coarse powdered bark with boiling water to make a poultice; cool and apply to affected area. Never apply slippery elm to an open wound. Source: Slippery elm | University of Maryland Medical Center, University of Maryland Medical Center Or, Preparations and Dosage Because slippery elm does not tincture well, its bark is powdered or cut into thin strips for tea. Like all demulcents, the bark is best prepared with a long soak in cold water. The powder is used as a healing food: Stir 2 to 3 tablespoons into juice, pureed fruit, oatmeal, or other foods. You can also mix slippery elm powder with hot water, bananas, and applesauce to prepare an oatmeal like gruel that can soothe an inflamed stomach or ulcer. (1) it reduces the amount of time digestives remain in the bowel; (2) it absorbs toxins from the bowel; (3) it increases the bulk of stools and dilutes stool materials thereby reducing stool contact with the intestinal mucosa; and (4) it enhances helpful bacteria processes in the intestines. The mucilage resists hydrolysis and digestion by stomachs acids and enzymes, meaning that it maintains it’s soothing action throughout the entire digestive system. The discomforts of heartburn or an ulcer may respond to slippery elm bark.