Caulking guns might seem like simple implements— lever, a spring, a notched shaft, and a few extra flourishes and what was once a slab of sheetmetal is now ready for sealing service.
Not so fast.
Like most other common tools, caulking guns can vary in durability and quality, and a variety of types are designed for different tasks. One of the most distinguishing characteristics of a caulking gun is its thrust ratio, which signifies the amount of power generated by each full trigger pull. A lower thrust ratio means you’ll need to apply greater force to the trigger, and more adhesive sealant material (aka “boat goop”) will be dispensed with each trigger pull.
The common hardware store caulking gun is typically a low-ratio gun, which will work fine with the store’s latex window caulks, and some silicones. However, the polyurethane sealants like Sikaflex 295 or 3M 5200 are much thicker.
Our technical editor Drew Frye became very familiar with industrial caulking guns decades ago while working in refineries as a beginning engineer. One of his early jobs was sealing concrete containment dikes. The dikes are sealed with thick caulks. Frye and his team used pneumatic guns for the long floor seams, and high-ratio manual guns for the tight spots and smaller repairs. A low-ratio gun would have left their forearms cramped and sore before the job was done.
TECH TIP: Caulking Guns
| THRUST RATIO | STROKES PER TUBE |
|---|---|
| 6 | 10-12 |
| 8 | 14-16 |
| 10 | 18-22 |
| 18 | 34-40 |
| 26 | 55-65 |
When Frye started testing adhesive sealants for Practical Sailor, he soon realized that although the favorite adhesive sealants were readily available at chandleries and big-box retailers, a proper caulking gun was not. Which is strange, because even the most devout keep-it-simple sailor will happily allow a caulking gun aboard. Although not “essential” – a squeeze tube will suit most small repairs – a cheap caulking gun inevitably works its way into the sailor’s toolbox by the first haulout, if not before.
By the time we are ready to embark on that long-awaited cruise and are choosing which tools leave ashore with our sons (only one of whom has ever held a caulking gun), it is too late. Not only has the cheap dented caulking gun proved its mettle, but our long experience with leaks and drips, and our dark premonitions of a leaking hull-deck joint halfway to Tahiti have elevated the status of our caulking gun to the status of essential emergency repair tool.
Too bad that we bought the wrong one.
While that Dollar Store low-ratio caulking gun will do just fine for sealing Aunt Beatriz’s picture window, it’s just not up to snuff for the true mariner. The dynamic stress of being underway at sea and exposure to the harsh marine environment makes it difficult to create at durable seal on any boat. Boat joints go through the same freeze and heat cycles as your chimney flashing, so your sealant is often as thick and goopy.
Imagine that chimney getting squeezed and levered as your house heels and punches to windward and you get some idea of the need for good adhesion as well as plasticity. Because of these added dynamic stresses, our marine goops—especially the polyurethane types—can be as thick and sticky as the stickiest roofing caulk, and much, much goopier than common latex caulk.
The viscosity, or “goop factor” (a technical term we just coined) is even more punishing for the impecunious mariner who preserves their leftover caulk tubes in the freezer to extend their useful life, or the anxious sailor works through the cold season. Good luck using a discount store caulking gun to pump out temperature and time-thickened polyurethane. If he’s lucky, the caulking gun buckles before his forearms revolt.
VALUE GUIDE: Caulking Guns
| MANUFACTURER | MODEL | TESTED | THRUST RATIO | PRESSURE AT 30 LBS. GRIP FORCE | PRICE |
|---|---|---|---|---|---|
| MODEL | |||||
| HDX | Composite | 8:1 | 240 | $9.97 | |
| HDX | Dripless | Tested | 6:1 | 180 | $5.97 |
| RED TREE | Heavy Duty | Tested | 10:1 | 300 | $9.29 |
| RED DEVIL | 3986 | Tested | 10:1 | 300 | $8.97 |
| SEAT | |||||
| HDX | Professional | 18:1 | 540 | $17.97 | |
| RED DEVIL | Extreme | 18:1 | 540 | $16.75 | |
| JES (Best Choice) | M26S (adjustable stroke) | Tested | 26:1 | 780 | $28 |
| NEWBORN (Recommended) | 250 | 18:1 | 540 | $29 | |
| NEWBORN (Recommended) | 375 XPS | Tested | 26:1 | 780 | $38 |
| COX (Recommended) | 41004-2T | 26:1 | 780 | $39 | |
| FUNNEL ONLY | |||||
| RYOBI | One+ Power Caulk Gun | N/A | 500 | $49.97 (+$28 for battery) | |
| RIGID | 18V Caulk Gun | N/A | 750 | $79 ($45 for battery) |
HOW WE TESTED
Apart from some bench testing to compare features, the bulk of our testing involved using the guns for various jobs and comparing performance. Some of the findings are also based on Frye’s long personal experience with caulking guns, which includes of industrial, household, and boat work.
WHAT WE TESTED
We tested a low ratios guns from Redtree, HDX (Home Depot), and Red Devil. We also tested a high ratio caulking guns from Newborn, JES, and Cox. (The Cox and Redtree guns were used but in good condition at the time of testing.)
OBSERVATION
After spending hours with the caulking guns reviewed here, Frye noted several key points to consider when choosing a caulking gun.
Pick a ratio. Thrust ratio is the ratio between the amount of force applied to the trigger, and the amount of compressive force applied to the caulking tube. A low ratio means less mechanical advantage is gained from lever and more grip effort is required to force caulk from the tube. This is tiring and reduces control when working with high viscosity sealants. Ratios range from 6:1, 8:1, and 10:1 for low pressure guns and 18:1 and 26:1 for high pressure guns (see table page 12).
We prefer 8 or 10:1 for pumping latex caulk. The beads are smoother and we get just the right amount of feedback when forcing sealant deep into cracks. For general use, 10:1 is good. On the other hand, as our hands get older, we often find ourselves reaching for our handy high-ratio gun even for latex caulk. In other words (but no less punny), in our weakening grip, the lighter-duty caulking guns have become a handful.
Temperature. Pumping polyurethane sealant in cool weather is a different story. Thick sealants are best applied with a 18:1 or 26:1 gun, depending on how warm it is and how strong your hands are. You can make a low-ratio gun work, but control is poor and it hurts, especially if you have joint inflammation. We also like the higher-ratio guns for asphalt sealants (roofs and driveways), although viscosity of products can vary greatly by temperature and by product.
Other features. Dripless delivery is nice. When applying latex caulk, unless you are lightning fast on the release and pull the rod back manually, excess caulk can shoot out, making a mess and wasting caulk. This is less dramatic with thicker urethane sealant, but they are much hard to clean up. Proquality guns release pressure with the tap of your thumb on a lever— no need to withdraw the pusher rod manually. Nice.
Unnecessary accessories. We don’t attach much value to tip cutters; they can’t cut the tip to the exact angle and length we have in mind. Sailors almost always have a knife or other cutter with them. Some guns come with a sealpoker, a short rod to break the inner seal. The poker, of course, gets covered in goop with each poke, so keep a rag handy and try to remember not to stick the tool back in your tool box or in your pocket.
Not missing an opportunity to cover our hands in goop and ensure we are attached to their product, some caulking guns have a designated spot to store the seal-poker along the caulking gun barrel, or in the handle—places where we usually grip the gun. Especially if you’re working with 3M 5200, or some other polyurethane, you’ll want to wipe the pin clean (not always possible without solvent) or wait until the caulk residue is cured before stowing this pin.
Skin protection. Plastic gloves offer little protection for your skin. The thin gloves, in particular, will stick and pull apart in chunks. Working bare-handed isn’t much better. Cleaning polyurethane from your skin requires mineral spirits, which can increase chemical absorption and result in dry skin. We like wearing tight-fitting coated gardening gloves; sticking is less problematic and the caulking generally will not penetrate them.
Rotating tips. Some caulking guns have a cartridge holder that rotates. By releasing the pressure and twisting the tube holder (the gun’s “barrel”), you can reorient the angle-cut tip to more precisely lay the bead of caulk. Of course, you can do this with any gun by turning just the caulk tube, but having a rotating tube holder makes this a little easier.
Adjustable stroke. By adjusting a lever stop above the handle, the stroke length can be reduced to suit smaller or tired hands. Given the larger handle throw of the industrial guns, this is a worthwhile feature.
Push too hard with the 26:1 guns and you will blow the tube apart. We did that more than once. If you’re curious to know if it could force a plug of 2-day old caulk out, we know: the tube blows before the plug and you’ll spend the next 10 minutes and lots of paper towels wiping down the gun. Our favorite method for clearing the old plug, if it is too hard to just pull out with our fingers, is to use an old 5/16- inch drill. Works every time.
LOW RATIO GUNS
Low ratio guns are best suited for latex caulk and silicone sealants.
RED DEVIL 3986
This caulk works fine around the house. We can even squeeze cold polyurethane out of it if we really bear down, but it’s hard work. We found the twinbar design provided a bit more resistant to bending and jamming. The design makes it relatively easy to relieve the pressure off the piston and rotate the tube. We finally broke the ratchet by squeezing too hard using polyurethane sealant that had been stored in the fridge.
Bottom line: Good for latex and silicone caulk.
RED TREE INDUSTRIES
This is a clone of the Red Devil 3986 but a few pennies more expensive.
Bottom line: Good for latex and silicone caulk.
HIGH RATIO GUNS
High ratio guns are suited for polyurethane, polyether, and polysulfide sealants. Asphalt roofing and paving sealants. All have rotating frames.
NEWBORN 250
Probably the most popular among contractors, the 18:1 ratio is a reasonable compromise for many applications. A professional quality gun.
Bottom line: Recommended for marine sealants, and perhaps the best allaround choice for home and boat use.
NEWBORN 360
We didn’t spend a lot of time with this one, but it was smooth and powerful.
Bottom line: Recommended for thick sealants.
JES M26S
Smooth operation, high power, good value, and an adjustable stoke length made this our favorite. We’ve used JES guns in industry; they hold up in that setting and a DIY a lifetime.
Bottom line: Best Choice for a high ratio gun.
COX 41004-2T
Cox has long been focused on the professional market, and we were not disappointed. Several local craftsman used this one and sang its praises.
Bottom line: Recommended for thick sealants.
ELECTRIC GUNS
Electric guns are recommended for Polyurethane, polyether, and polysulfide sealants. They’re also good for asphalt roofing and paving sealants.
RYOBI ELECTRIC
This gun’s variable speed is nice. Though not a heavy duty brand, we met one fellow that used it professionally.
Bottom line: Recommended for big jobs.
MILWAUKEE
Although we didn’t use this gun for more than a few quick squirts, the man recaulking his deck was smoothly working his way down each row of seams, making casual work of a tiresome job. Milwaukee has a reputation for pro quality, so expect it to last.
Bottom line: Recommended for big jobs.
CONCLUSIONS
You get what you pay for, and everything about the pro-level guns works better. Cheap guns will break if you force them and won’t move thicker caulks. You can also get professional quality low pressure guns from JES, Newborn, and Cox, but at lower pressures the differences in quality are less apparent.
You’ll really enjoy an 18:1 or 26:1 ratio when pumping thick stuff around the boat. As the force increases, professional quality matters. We heard complaints of some of the cheaper high ratio guns folding up when squeezed too hard.
We preferred the lighter weight, control and simplicity of a manual gun for most jobs. Most days, all we need is a fraction of an ounce to bed something. But sailors recaulking teak decks sing the praises of electric guns. Next time we run into a big job, that Milwaukee is looking pretty good and we’ve even got the batteries.
Top tier guns cater to small hands, weak grips.
Sure, the casual user can survive with a cheap caulk gun—but our aim is comfort and proficiency, not survival. The details that make a good caulking gun stand out may seem small, until you start to work. It will take only one long bead to realize how much easier a job is (and dare we say, fun?) when you have a good caulking gun.
1. The stop screw in at the top of the JES caulking gun controls the amount of throw in the trigger. This adjustment helps regulate the amount of material pushed out with each trigger pull, as well as the amount of force each trigger pull requires. It can also be a handy aid for people with small hands. If you can’t grip the fully open gun, you can reduce the grip opening distance.
2. The trigger end of the JES gun has a more ergonomic pistol grip that keeps your hand from slipping upward to a position where you will lose most of the handle’s mechanical advantage.
3. Our players included a deluxe model from JES, a basic model from Red Tree, and a mystery gun from the past.
Even opened polyurethane can keep for months in cold dry conditions.
In the case of polyurethanes (Sika 291 and 295, 3M 5200 and 4200, Loctite PL S40, and others) water is the curing agent, and no matter how carefully you seal the tubes, within a month or so they harden up. Because the absolute humidity in a refrigerator is very low, and because cold slows chemical reactions, storage times are much longer. Sealed with aluminum foil, we routinely get 6-8 months, and often several years, before they slowly thicken beyond practical use.
The storage time of less problematic materials, such as latex, polyether, and silicone sealants, are also extended, typically for years. Don’t let latex freeze.
We’re not keen on this approach for flammable (possible explosion) or toxic materials, but we’ve been storing sealants in the crisper of our sealed drink fridge for a decade. It’s nice to have caulk ready for when you need it.
