A few nanoseconds after Heather had finished her lecture on house elves, she turned to the Yellow Quartet and said "Harry, Amy, Susan, and Hannah and said, "Let me see your wands."
Harry, Amy, Susan, and Hannah all handed Heather their wands and she inspected them one by one. Heather frowned when she examined Harry's and Amy's wands but smiled when she evaluated Susan's and Hannah's wands.
"Susan, Hannah, " smiled Heather, "Your wands are in outstanding condition."
Heather handed Susan and Hannah their wands back and turned to Harry and Amy with a serious kind expression.
"Harry, Amy, " said Heather calmly, "I'm not criticizing you, but both of your wands are filthy. Now, there are plenty of pureblood wizards who either don't know or don't practice proper wand care so I'm not singling either of you out."
"But mom and Amelia Bones are very knowledgeable about wand care and have passed that knowledge on to us, " said Hannah, giving Heather a smile.
"Yes, " said Heather briskly, "Now Harry, Amy, are either of you familiar with any wand care products?"
"No, " chorused Harry and Amy.
"I thought not, " said Heather, "Wand care products are not part of Hogwarts required school supplies. Not all witches and wizards know of the existence of these products and some who do either don't think to get them or chose not to get them because they aren't required. But to get the best performance out of a wand, it needs to be well cared for."
"Does Olivander sell these products?" asked Harry.
"No, " said Heather clearly, "They are sold at a separate, lesser known shop in Diagon Alley known as Smart Sorcery Supplies."
"Even if such products would be useful, " realized Harry, "We can't risk a trip to Diagon Alley-"
"There's a way around that, "Smiled Heather, "But first, let's get you familiar with what these products are. First there are wand holsters. They are long rectangular boxes that have been bewitched with Anti Dust charms. All the wands in Olivander's shop are stored in such holsters until they are sold. Wand holsters are mainly used to store wands when the owners of the wands are getting some shut eye."
"But they help prevent the buildup of dust on wands when wands are not used, " realized Harry.
"Very good, Mr. Potter, " smiled Heather, "Another useful wand care product is wand polish."
"That sounds pretty self-explanatory, " piped up Amy, "But how often should wand polish be applied?"
"Once a week and no more, " said Heather, "While wands do need to be cleaned periodically, using too much polish or using it too frequently will cause the wood finish to start to peel away. You will both need to be taught how to polish your wands and I will be teaching you how as soon as we acquire the supplies to do so."
"Is that it then?" asked Harry.
"No, " said Heather firmly, "You can also buy wand tape. Wand tape is a thin and clear tape that cannot be seen once it placed onto a wand. But this tape is actually an alarm. If your wand has wand tape on it, it will sound an alarm if you store or place your wand in an unsafe place."
"That sounds useful, " said Harry matter of factly.
"It is, " confirmed Heather, "But there's also the matter of how to handle your wand. Wands should only ever be held from the bottom. Fingerprints add up fast on wands. That's one reason for the polish of course. But it's best to limit the buildup in the first place. Topsy?"
"Mistress Heather called?" piped up Topsy.
"Yes, " said Heather simply, "Topsy, I want you to go to Smart Sorcery Supplies and buy two complete sets of wand care supplies, one each for Harry and Amy."
Next nanosecond, the house elf vanished.