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How to Seal Ceramics to Prevent Leaks

Broken treasure? Let's fix it!

Broken treasure? Let's fix it!

How to Waterproof a Ceramic Vase

You're digging through those dusty boxes in the garage when you come across a fantastic piece of ceramic ware: a vase, a flowerpot, a casserole dish, etc. You decide to finally put it to good use. But minutes after putting it into action, you learn why it was boxed up: it leaks like a sieve!

Fortunately, your great-looking ceramic doesn't have to go back in the box, and it doesn't have to be relegated to the display cabinet. You can seal it inexpensively with equipment you already have at home, without detracting from its value. The sealant will be easily removable (and almost invisible). On a winter afternoon, if you have nothing better to do, seal up those ceramics. Start enjoying them as they were meant to be used!

You Will Need

Most of what you will need you probably already have at home:

  • Hairdryer
  • Hot plate
  • Several metal cans
  • Metal jar lid
  • Potholders

You will probably also need an extra person to help out if any of your pieces are of substantial size. If you're planning to serve food in your ceramics, see the second part of this article.

If you are not planning to use the item for food, the only thing you will need to buy is paraffin wax, which is usually used for making candles. Even if you are not planning to serve food in your ceramic dishes, it's best to get food-grade paraffin, which has dozens of uses around the house, including canning and making chocolates!

How to Make the Seal

  1. Use your hot plate. Fill a large, sturdy metal can with three inches of water, and place a small metal object like a jar lid or empty tuna can in the bottom, upside down.
  2. Scrape off some paraffin (it will take more than you think) into a second, smaller metal can and place inside the first.
  3. Put the entire contraption on the hot plate and turn it on to melt the paraffin.
  4. Get your ceramic piece and wipe down the inside with a damp rag so it is clean. When the paraffin is melted and ready for use, get a second person to hold your ceramic item with a potholder.
  5. Heat the inside first, then the outside of the pot or vase with a hairdryer until it is hot to the touch.
  6. Quickly pour the paraffin inside, and, holding the item so that the mouth is parallel to the floor, rotate it so that the paraffin touches the entire inside and will seal the item against leaks.
  7. Set the piece aside to cool (put it on a trivet or potholder).

If at some time in the future you need to remove the paraffin, it removes easily with a hairdryer. Just warm the wax up, and it will peel or chip right off. Another warming and you can wipe up any stray paraffin with a rag. (Dispose of the rag properly to avoid starting a fire!)

Sealing Ceramic Cooking Dishes

If you have a ceramic casserole dish, glazed or unglazed, and it leaks, there is an easy fix. You simply submerge the piece in whole milk, heat gently for at least one hour, and let cool overnight. Remove the piece from the milk the next morning, and rinse.

The milk will seep into the pores of the ceramic and the proteins will bond with the molecules of the ceramic dish. You will have an invisible seal and, of course, since you used food to seal it, the dish will be food-safe.

Even after you seal your ceramic baking dishes, it's a good idea to soak them in warm water for two hours before baking in them (you can dry off the insides). The water will help prevent leaks, surprisingly!

If you run your ceramic baking dishes in the dishwasher, you may need to reseal them with milk occasionally.

Questions & Answers

Question: We use a huge ceramic bowl as a water feature. Because of an early frost, protecting the bowl didn't happen, and it's developed a leak in two places. We repaired it, but it turns out, almost two months later, the epoxy we used is now lifting off, and the bowl is leaking again. We cannot repair it from the outside, as it is buried. However, it can be repaired inside, and down to where the bowl meets the ground. Do you have any suggestions?

Answer: You can try brushing melted wax on the interior and letting it dry. You could also try a different kind of resin (the food-grade kind used for repairing leaks in glasses). However, if you're using it as a water feature outside, and it's not leaking too badly, consider that you might just be watering the soil around it and leave it be. If it remains filled fairly well, then leave it alone.

Question: What do I use on the bottom to seal ceramic dishes to prevent mold?

Answer: My answer is to put a very thin layer of wax on the outside of the dish.