The ratio on a manual gun is mechanical advantage: how far the plunger moves for one full squeeze. A 12:1 gun moves the rod further per stroke, so material comes out faster but each squeeze is harder. An 18:1 gun moves it less per stroke and multiplies your hand force, so a stiff sealant extrudes smoothly instead of in jerks.
Quick answers
Should I buy a 12:1 or an 18:1 sausage gun?
18:1 for structural grades, stiff sealant, cold weather and long overhead runs; 12:1 for general weatherproofing on a warm day. If you buy one gun for everything, take 18:1.
Can a cartridge gun take a sausage pack?
No. A sausage loads into a closed barrel with a plunger disc behind it and a nozzle on a front cap, so it needs a sausage gun.
Is a gun included with the sealant?
No. The gun is sold separately, and one 20 fl oz gun fits every sealant we carry.
Which ratio for what
| Sealant | Ratio | Why |
|---|---|---|
| General weatherproofing, warm day | 12:1 | Flows easily, you want speed |
| Structural grade, high viscosity | 18:1 | Stiff material, you want control |
| Cold weather, any grade | 18:1 | Cold sealant is much stiffer |
| Long overhead runs | 18:1 | Less hand fatigue over a shift |
If you are buying one gun for everything, take the higher ratio. You lose a little speed on easy material and gain control on hard material, and your hand lasts the day.
Why sausages and not cartridges
- More material per load. A 20 fl oz sausage holds roughly double a standard cartridge, so you reload half as often on a long run.
- Almost no waste. The foil collapses. A rigid cartridge leaves material stuck to the wall of the tube.
- Far less rubbish. A flat foil against a pile of plastic tubes matters on a site with one skip.
The trade-off is that a sausage gun is not a cartridge gun. The sausage loads into a barrel, a plunger disc seals behind it, and the nozzle screws onto a front cap.
Loading it
Cut one end of the sausage, load it cut-end forward, fit the plunger disc behind it, close the cap with the nozzle on, and advance the rod until sealant reaches the nozzle. Cut the nozzle to the joint width at 45 degrees — not wider, because you cannot take material back off.
Warm it first in the cold
Cold sealant is dramatically stiffer. Before a structural grade on a cold morning, bring the sausages up to room temperature — in the van cab overnight, not on a heater. It extrudes cleanly instead of surging, and you get a bead you do not have to rework.
One gun, whole range
Every sealant on this site ships in the same 20 fl oz (600 ml) foil sausage, so one gun serves Seimeda, Silande MF898 and MF899 and DOWSIL 795. The gun is not included with the sealant.