Filling lip balm tubes: tray or freehand, overfill, top-up and the defects each one causes

Fill weights for tubes, tins and jars, the 8-15% overage rule, pour height and speed, why you overfill and scrape, when to top up, and a defect table with causes.

The melt is chemistry. The fill is craft, and it is where most home batches lose their finish. Nothing here changes what is in the balm, but it decides whether the stick has a flat glossy top or a crater, whether the tube twists smoothly, and whether you end up with 22 good units or 19 good units and three you cannot sell or gift.

Before you pour: set up so the pour never waits

A pour is a timed operation. Once the melt leaves the bath it cools by roughly a degree a minute in a small stainless jug, faster in a thin-walled beaker, so every second spent hunting for something is a degree of pour temperature gone. Have all of this ready before the wax goes into the bath.

1. Containers out of the bag and upright. Do not wash tubes. A rinsed tube never dries properly inside, and residual water in an anhydrous product is exactly the condition that would need a preservative. Wipe the outside with isopropyl alcohol if it is dusty and leave the inside alone.
2. Mechanisms wound fully down. Check every tube. A disc sitting even 2 mm up costs you fill weight and leaves the user winding down into a void.
3. Tray or jig level. A tray sitting on an uneven bench gives you a batch of sloped tops. Check with the edge of a ruler, not by eye.
4. Bench clear, hair tied back, one clean spatula. Full practice is on workshop hygiene. The short version: this is a leave-on product going on a mucous membrane and it has no preservative.
5. Batch record started. Batch code, date, formula version, and the number of units you expect. Write the expected number down before you pour, so you find out honestly whether your overage was right.
6. A warm tray if the room is cold. Tubes at 30 to 35 C fill better than tubes at 15 C, and warming the container is always better than raising the pour temperature.

Tray versus freehand

A filling tray is a block that holds tubes upright at a fixed height with a flat plate across their tops. Its real function is not speed, it is that the plate becomes a reference surface: you can pour past the rim, let the excess set on the plate, and scrape the whole batch flat in one pass. That produces a consistent, level top that freehand pouring cannot match reliably.

Freehand means holding or standing tubes in a jig and filling each to just below the rim. It is slower per unit and the tops vary, but it wastes less balm, needs nothing you do not already own, and is genuinely fine below about 20 tubes. A strip of stiff card with holes punched to the tube diameter, taped over a shallow box, holds five to ten tubes as securely as anything sold for the purpose.

Fill weights and how big a batch you need

Work in grams, never in millilitres. Use 0.92 g/mL as the working density of a finished balm if you need to convert a container's stated volume into a fill weight, and remember that molten balm is less dense than set balm, which is exactly why tins dip in the centre as they cool.

The overage rule is 8 to 15% above the sum of your fill weights, to cover what clings to the jug, the spatula, the thermometer and the tray plate. Use 8% for a large batch in a stainless jug with a good spout, and 15% for a small batch, a viscous high-wax formula, a borosilicate or silicone vessel, or any batch where you will be doing top-up pours from a cooling jug.

Worked example. Twenty-four oval tubes at 4.5 g each is 108 g of balm in the containers. At 12% overage the batch is 108 x 1.12 = 120.96 g, so weigh out 125 g and accept a small remainder. At 8% it would be 116.6 g, which is enough only if your equipment is genuinely low-loss. If you would rather the arithmetic did itself, the batch calculator converts units into batch weight, and scaling beyond a few hundred grams brings its own issues, set out on batch scaling.

The pour itself: height, speed and one continuous movement

Hold the spout 5 to 10 mm above the tube rim. Higher than that and the falling stream entrains air, which shows up as bubbles at the top of the stick and occasionally as a void further down. Lower and you will touch the rim, which drags balm down the outside of the tube and leaves you cleaning threads later.

Pour in one continuous movement per tube, at a speed that keeps a coherent stream rather than a dribble. A broken stream lays down layers that set against each other and leaves faint horizontal lines in the finished stick. Do not stop halfway to check the level, and do not go back to a tube you have already left, because the second addition arrives on a surface that has begun to set. Pour, move on, come back for the deliberate top-up later.

Keep the jug moving between tubes rather than resting it, so the melt stays mixed. If you are pouring more than about 30 units from one jug, return it to the bath partway through: the last tubes in a long run are always the coolest pour, and they are the ones with flow lines. The whole temperature question is set out on pour temperatures.

Why you deliberately overfill, and how to scrape

Overfilling is not carelessness, it is the point. Balm contracts as it solidifies, so a tube filled exactly to the rim ends up below the rim with a dished top. Filling past the rim gives the contraction somewhere to come from.

With a tray, pour until a small dome stands proud of the plate, let the whole block set for 20 to 30 minutes, then draw a stiff blade or a scraper flat across the plate in one pass. The excess comes off as a sheet, goes back in the jug and is remelted with the next batch, so it is not waste unless you leave it on the bench. Do not scrape while the balm is soft: you will smear rather than cut, and you will pull material out of the tubes.

Freehand, the equivalent is to fill to about 1 mm below the rim, accept that a dip will form, and rely entirely on the top-up pour to produce the final surface. That gives a slightly domed top instead of a flat one, which is what most handmade balm looks like and is entirely acceptable.

The second pour: when to top up

Ten to fifteen minutes after the first pour, the surface has skinned and the core is still warm. That is the window. Test it with a fingernail at the edge of one tube: if it leaves a mark but no liquid appears, top up now.

Pour a thin second layer, just enough to fill the crater and stand slightly proud. A transfer pipette is better than the jug here, because you are placing 0.1 to 0.3 g per tube. Keep the jug in the bath at pour temperature while you do it, or the top-up itself will be too cool and will sit as a visible disc.

Two failure modes to recognise. Topping up too early merges the new balm into a still-liquid centre, so you simply repeat the original contraction and get the same dip again from a slightly higher starting point. Topping up too late bonds poorly to a fully set surface, and the disc shears off the first time someone winds the stick up. If your dips are deep enough to need two top-ups, the real problem is pour temperature, and the diagnosis is on tunnelling and dips.

Capping, cooling and cure

Cool upright at room temperature. Resist moving the tray for the first ten minutes: a knock while the surface is setting leaves a permanent ripple. If the formula contains shea and you are cooling deliberately fast, use the fridge for about 20 minutes rather than the freezer, because cooling below 18 C favours the unstable alpha form and adds contraction cracking without buying lasting stability.

Cap when the balm is fully set and back at room temperature, usually one to two hours. Capping warm marks the dome and traps warm air that condenses on the inside of the cap. Then leave the batch 24 to 48 hours before judging hardness, because wax crystallisation is still finishing and a balm assessed at two hours reads softer than the same balm at two days. A stick that feels right on day one and draggy on day three has not changed formula, it has finished setting, which is a common false diagnosis on balm too hard or too soft.

The twist-up mechanism, and what a hot fill does to it

A standard twist-up tube is a polypropylene barrel with an elevator disc riding on a threaded screw driven from a turning base. The disc is a moving seal, and it is only as good as its fit.

Fill too hot and the balm is thin enough to wick past that seal into the screw thread underneath. There it sets, and one of two things happens: the thread jams and the tube twists stiffly or not at all, or the balm continues through and seeps out of the base, which the customer discovers in a pocket. Very hot balm can also soften the barrel enough to distort the bore slightly, which produces the same symptom by a different route. Both are avoided by staying inside 65 to 72 C.

The other mechanical points are simpler. Fill with the disc fully down, always. Do not overfill so far that balm gets into the cap seat, or the cap will not seat and will pop off in a bag. And accept that tube quality varies: the fit between disc and barrel is the single thing that differs most between cheap and good tubes, and it is worth testing a sample before buying a thousand. Container choices are compared on the packaging guide.

Labelling, after the cure

Label at 24 to 48 hours, not at two hours. Two reasons. First, a warm tube outgasses slightly and lifts the label edge. Second, and more practically, every tube you have handled during a pour has a trace of oil on it, and adhesive does not stick to oil. Wipe each tube with isopropyl alcohol on a lint-free cloth and let it flash off before applying the label.

Record the batch code on the label or the base. If you give balm away, that is how you trace a complaint back to a batch; if you sell it, it is a requirement rather than a nicety, and what has to appear on the label is set out on labelling cosmetics in the US.

Defect table: what the tube is telling you

Getting a consistent batch, not one good tube

The difference between a hobby fill and a repeatable one is that the second is a sequence you do the same way every time, in the same order, with everything in reach before the heat goes on. Write your own version of the sequence on a card and keep it with the tray. Then change one variable at a time: pour temperature, or top-up timing, or container warming, never two at once, and cut a test tube each time so you are judging the inside rather than the top.

The equipment that actually helps is short, and it is not the tray, as set out on equipment. If your fills are consistently good and the balm itself is still not right, the problem has moved back upstream to the formula, and the starting point for that is how to make lip balm.

Reviewed and updated 6 September 2026. Spotted an error? Tell us and we will fix and log it.