How To Plug a Hole at the Bottom of Pottery
What is best to plug the hole in the bottom of a pottery pot before sealing it as a fish pond?
Selleys Knead It Aqua is the right product for this. Cut off enough for the job, mix it thoroughly between your fingers until the putty is a uniform colour, then force it into the hole and feather the putty out to the edges so the hole is fully sealed.
One preparation step makes a real difference: give the inside of the hole a bit of a scratch up first. A keyed surface gives the putty something to grip, and a drainage hole in a glazed pot is otherwise about as smooth a surface as you will find.
Why an epoxy putty rather than a sealant
A drainage hole in a pot is a static void, not a moving joint. Nothing about it flexes. What it needs is a plug that fills the hole completely, bonds to the sides, and holds up under permanent water contact.
That is what Knead It Aqua is. It is a hand-kneadable, fast-setting co-extruded epoxy repair system designed for rebuilding, reshaping and repairing damp, wet or underwater substrates — a white hardener encapsulated in aqua-green resin, which turns off-white once you have mixed it properly. The colour change is your mixing indicator: keep kneading until there is no green marbling left, or the unmixed portions will not cure.
A flexible sealant would be the wrong tool here. Its whole value is in accommodating movement, and there is none to accommodate. The putty's hardness is an advantage in a plug.
Published figures
| Property | Knead It Aqua |
|---|---|
| Type | Two-part epoxy putty, co-extruded |
| Appearance | White hardener in aqua-green resin; off-white when mixed |
| Pack sizes | 110g plastic tube; 50g blister |
| Working time | 20–30 minutes after mixing |
| Hardens | 20–30 minutes |
| Initial cure | 60 minutes — can then be machined, drilled, sanded, filed, sawed and painted |
| Full cure | 24 hours at 25°C |
| Application temperature | 5 to 40°C |
| Heat resistance | −40 to +120°C continuous; −40 to +140°C intermittent |
| Drinking water standard | Complies with AS/NZS 4020 for contact with drinking water at temperatures up to 85°C |
Indicative data only, not intended for the preparation of specifications.
What the figures mean for a pond pot
The AS/NZS 4020 compliance is the number that matters most here. That standard covers products used in contact with drinking water — it is the same test regime Selleys cites for its potable-water-approved roof and gutter sealants. For a plug that will sit permanently under water with fish in it, a product tested against that standard is a materially better position than one that is simply "waterproof".
A 20–30 minute working time is generous but finite. Cut off only as much as you need for the hole in front of you. Set time increases below 20°C, so on a cold day you will have longer to work but a longer wait before it hardens.
Full cure is 24 hours at 25°C. Do not fill the pot the same day. If you are also applying a pond sealer over the whole pot afterwards, let the plug reach full cure first so you are coating a hard surface rather than a soft one.
How to plug the hole
- Clean the area around the hole, inside and out, so it is free of dirt, grease and loose material.
- Scratch up the inside face of the hole with a file, a rasp, or coarse sandpaper wrapped round a dowel. This is the step that most improves adhesion.
- Cut off enough putty for the hole with a knife. Err on the generous side — you want the plug to fill the full thickness of the pot base, not just bridge the opening.
- Knead it thoroughly between your fingers until the colour is completely uniform. Streaks of green mean unmixed resin, and unmixed resin does not cure.
- Force the putty into the hole so it fills the full depth. It will not sag, run or drip, so it stays where you put it.
- Feather the putty out to the edges on both faces so the seal continues past the rim of the hole onto sound pottery.
- Leave it 60 minutes to reach initial cure, then sand or file it flush if you want a flat finish.
- Allow the full 24 hours before filling the pot or applying a pond sealer over it.
Limitations — where Knead It Aqua should not be used
- Not recommended for filling joints and cracks subject to movement. The cured product is extremely hard and inflexible. It is a plug and a rebuild material, not a joint sealant.
- Will not adhere to polyethylene, polypropylene or Teflon. If the pot has a plastic insert or bung, check what it is made of first.
- Set time increases significantly below 20°C. Work indoors or wait for a warmer day if you want the published times.
- Application temperature range is 5 to 40°C.
- The AS/NZS 4020 compliance applies to water at up to 85°C. That comfortably covers a garden pond.
A note on the pond as a whole
Plugging the hole and sealing the pot are two separate jobs, and the answer above covers the first. Selleys' guidance here is to plug with Knead It Aqua before sealing the whole pot with a pond sealer — so the plug goes in first, cures, and then the coating goes over the top of it. Follow the pond sealer manufacturer's own directions for the coating stage, including anything they say about compatibility with an epoxy patch and about how long to leave the finished pond before adding fish.
Common questions about plugging a hole in a pottery pot
How much putty should I cut off?
Enough to fill the full thickness of the pot base plus a little to feather onto the surrounding surface. Cutting a second piece later is fine — the two will bond while the first is still workable.
How do I know it is mixed properly?
By colour. The resin is aqua green and the hardener is white; mixed correctly the putty turns a uniform off-white with no streaks.
Can I apply it if the pot is already damp?
Yes. Knead It Aqua is designed for damp, wet or underwater substrates and can be used under fresh or salt water.
Can I sand it flush afterwards?
Yes, 60 minutes after mixing. At that point it can be machined, drilled, sanded, filed, sawed and painted.
Will it be safe for fish?
Knead It Aqua complies with AS/NZS 4020 for contact with drinking water at up to 85°C. Follow the pond sealer manufacturer's directions for the coating you apply over it, including any curing period they specify before stocking the pond.
How long before I can fill the pot?
Full cure is 24 hours at 25°C, and longer below 20°C. Wait for full cure before filling.
What if the hole is very large?
Knead It Aqua has good gap-filling properties and will not sag, but a large opening is better backed from behind with something solid so the putty is filling a recess rather than spanning a void.
Would a silicone sealant do instead?
Not for this. Selleys' wet-area and glass silicones are excluded from permanent water immersion, and the products that are approved for water contact are not putties. Knead It Aqua is the product Selleys names for this job.
Is this the same product used for pool cracks?
It is one of the two Selleys names for underwater crack repair — see fixing a hairline crack in a pebblecrete pool, where the choice between Knead It Aqua and Marine Flex turns on whether the defect moves.
What is the best product to plug a hole in the bottom of a pottery pot before sealing it with pond sealer?
Selleys Knead It Aqua is recommended, especially if the pottery will hold water, because it is a hand-kneadable epoxy putty that can be applied to wet or damp ceramic surfaces and adheres well to ceramics.
Why is Selleys Knead It Aqua a good choice for pottery that will hold water, like a fish pond pot?
Selleys Knead It Aqua works on wet substrates, adheres to ceramics, provides a permanent repair, and once fully cured is approved for contact with drinkable water, meeting AS/NZS4020 standards.
How long does Selleys Knead It Aqua take to work with and fully cure?
Selleys Knead It Aqua has a working time of 20-30 minutes and reaches full cure in 24 hours.
How do you apply Selleys Knead It Aqua to plug a hole in pottery?
Cut off the required amount of the epoxy putty, knead it with your fingers until it reaches a uniform color, press it firmly into the hole, and smooth it before it hardens.
Is there an alternative product if the pottery pot is completely dry?
Yes, if the pottery is dry, Selleys Knead It Multipurpose is also suitable, offering excellent adhesion to ceramics with a quick working time of 3-5 minutes.
Can Selleys Knead It Multipurpose be finished or worked after it cures?
Yes, once cured, Selleys Knead It Multipurpose can be drilled, sawed, sanded, and painted, with full cure achieved in 24 hours at 25°C.
What surface preparation is recommended before plugging a hole in pottery?
The area around the hole should be clean and slightly roughened to ensure the best adhesion of the epoxy putty.
Once cured, can Selleys Knead It Aqua be machined or shaped?
Yes, Selleys Knead It Aqua is machineable when cured, meaning it can be sanded, drilled, or filed for a refined finish.