Ok, here is a wee update to this thread; it may be of use, it may not.
The vast majority of flanges made for ostomates make their wafers/flanges/base plates, whatever you want to call them, from 2 main ingredients: hydrocolloid and pectin.
The hydrocolloids used in flanges are derived from natural sources. For example, agar-agar and carrageenan are extracted from seaweed, which are the main two sources used.
So, to save you from all the boring science, basically, they are natural gelling agents mixed with water to form the gel for the flange. These hydrocolloids can also exist in their liquid states and will try to revert back to liquid with the addition of heat or extreme cold, hence the fact that flanges get extra tacky in hot weather or baths. It's because they are starting the process of returning to a liquid state. Also, hence the fact that urostomates and ileostomates find the flanges start deteriorating quite rapidly. High enzyme output in ileostomates and acidity in urine with urostomates is also a major factor.
((Drifting off slightly, there are a few simple techniques to reduce the acidity of your urine which has a twofold advantage, as it extends the lifespan of the flange and reduces the risk of uric acid stones. High intake of neutral fluids such as water, tender coconut milk, diluted buttermilk, and citrus juices all lower urine acidity (unless contraindicated for some other reason).
Also, try to limit the amount of tea, coffee, and cow's milk to 1-2 cups a day, vegetarian foods, and high fiber also reduce acidic urine. Meat eaters should try to limit protein to 1 gram per kilogram a day. Also, try to avoid cold drinks that contain a high amount of sugar and calcium-rich sweets made using milk as a protein, especially on an empty stomach))
Sorry about that folks, I do have a tendency to waffle lol.
Pectin is used in flanges as a stabilizer to combat the issues I have mentioned above and is, as we all know, the sugar that comes from fruit. The pectin used in the manufacturing of flanges is extracted from citrus peel or apple pomace (pulp).
So if you have an allergy to any of the mentioned ingredients, you may find you will also have problems when it is used in flanges as it can cause blistering and sores on the peristomal skin.
Is there an alternative option? Perhaps not, contact ostomy pouch manufacturers to see if they have alternative options, but I am aware that some countries only have one ostomy provider.
Also, it is probably a good idea to have an allergy test from your G.P. to determine whether or not you are indeed allergic to any of the ingredients. Also, a simple patch test will determine whether you will be prone to reactions from the flange of the pouch you are using.
To do a patch test, cut a small section from one of the flanges you are using and stick it to the inside of your forearm under a plaster and leave it for 48hrs. If it shows an irritation, then it is likely you will have problems with that specific flange, but to be sure, to be sure (as they say in paddywhack land), it's best to have an allergy test done by your G.P. for the aforementioned ingredients.
I hope this is of use to all those suffering from ongoing peristomal skin problems, as this may very well be the cause of your problems.