Dead space loss: weighed ten 0.5mL insulin syringes

I did the same with 1mL 29g syringes: 0.01-0.012mL residual. Smaller barrel helps, but the fixed hub hides water. Low-dead-space 1mL got me to 0.004mL.

Low-dead-space made a bigger difference for me than luer lock. The luer hub held a tiny ring unless I primed it, which defeats the point.

Wait, are you weighing with the plunger fully bottomed? I get different numbers needle on vs off. Fridge door temp swings matter for BAC water, not dead space.

I ran a similar test over two weeks with 0.3mL and 0.5mL BD syringes. Residual was less about brand and more about push speed.

Slow push left 0.003-0.004mL; fast push left almost double. I also tried a 1mL luer lock with a 30g 8mm needle, and the hub needed about 0.02mL to clear before anything came out.

For me that's not worth it unless I'm drawing larger volumes. The low-dead-space fixed needles win for small draws.

Curious if anyone has weighed after a 10-second hold instead of pulling right away?

Fast push vs slow push—never really considered that a variable worth comparing.

Luer lock kind of stops making sense once volumes get small. Those 0.3mL insulin syringes leave less behind, and an old test strip case with a couple alcohol pads holds them perfectly. Storage win, honestly.

0.17mL over 28 draws adds up if the vials are small. Low-dead-space is the first thing worth trying. Luer lock only really wins when needles get swapped between draws, and in most setups they don't.

I ran the same test on ten 1mL 31g BD and averaged 0.004 to 0.005g, then re-weighed the same ten a few minutes later and every sigle one had dropped another 0.002g — that's evaporation, not dead space, which makes me think your 0.006 average is partly inflated by how long each one sits out before it hits the scale. The other thing that messed with me was scale drift: I tared a sealed cap and it wandered 0.003g over twenty minutes, basically half of what I thought I was measuring.

So I stopped chasing the syringe and started weighing the whole vial before and after a session instead, and the truth is the hub leftover is the small piece of the pie — what actually bit me was the tail end of a small vial drawing short, and I fixed that by just calling it done earlier instead of scraping for every drop. 0.17mL over six weeks feels annoying until you compare it to what a single impatient draw costs you.

Fourteen weeks of Sunday-morning waist measurements taught me the same thing the hard way — my waist has swung 1.25 inches between consecutive weeks, and my scale jumped 3.5 lb overnight after a salty dinner, which is a lot more noise than anything left in a syringe hub. I tracked obsessively for the first six weeks, then my scale battery died for nine days and the tape measure was all I had, and that stretch produced the cleanest trend line I'd seen because I wasn't arguing with a daily number.

Weirdly I got more consistent with my routine after that, not less.

Are you logging anything besides the scale, or is the syringe accounting basically your control variable right now?

I went the other direction: weigh the vial, not the syringe. Same 0.001g scale, zero with an empty identical vial, let both sit 10 min.

Pre/post mass over a whole vial catches hub loss, drips, and whatever clings to the stopper. My residual was tiny; most of my “missing” volume was me drawing a hair shy because I was eyeballing the plunger. Are you comparing syringe weight to vial weight? That gap is the tell.

I stopped chasing the per-syringe number and started logging per-vial yield: date opened, date empty, and how many full draws I actually got. The label math said one number; real life was usually 1–2 short.

That gap was dead space plus my own sloppy “one more tiny draw” habit. Now I just track that yield and adjust when a vial dies early.

Are you tracking per-vial, or only the residual test?

I found the vial-level number more useful because it includes all the little losses I don’t see.

I lift 4x/week and track recomp stuff, so I get the obsessive streak. The dead-space number that actually mattered to me wasn't per syringe—it was whether my scale stayed linear across the range.

I tested 0.005g, 0.010g, and 0.020g with calibrated weights and found my cheap scale was fine at 0.020 but ±0.003 at 0.005. That's the same order as your residual. Did you check linearity or just tare zero?

I’ve got the same 0.001g scale, and mine gets moody if it’s not perfetly level—AC on, readings wander

the AC thing is real—mine only cooperates after I level it and apologize lol

I’m in the same obsessive camp, but my scale only goes to 0.01g, so I went low-tech: I mark a tiny dot on the vial label for each draw and note when the stopper starts that squeaky “last pull” feel. Weirdly, I saw more residual when I rushed the draw; slowing down and pausing before the final pull seemed to leave less in the hub.

Did you compare slow vs quick draws?

I’m plateaued hard too, so this is the only variable I can fiddle with without losing my mind.

I’ve been doing a low-key version: weigh the whole vial before and after each draw on my little scale, log it in a note with my walk/meal-prep stuff. My “vial tax” looks pretty constant per draw, not per volume, so I stopped trying to chase the worst-case.

One thing I’m curious about: have you compared residual after a quick full depress vs a slow one? I swear mine leaves a bigger bead if I rush the last bit, but I haven’t tested enough draws to know if that’s real or just me.

My little pharmacy scale gets moody if the AC kicks on—solidarity on the dead space math lol

newbie wek one here, already deep in the dead space anxiety lol. Solidarity!