Heavy Duty Convex Jointer

• Art. Nr: 300033, 300036, 300037
• Size: 3/8"x1/2", 3/4"x7/8", 7/8"x1"
• Material: Heat-treated
• Construction: One-piece S-bent steel bar, half-round convex working end at each end, size stamped at the center
• Handle: No separate handle; held at the flattened center section

Product Name & Model

Product Name: Heavy Duty Convex Jointer

Art. Nr: 300033, 300036, 300037 (three article numbers)

Product Line: Leading Tools Brick Jointer range, sitting between the Grapevine Jointer (300024–300025) and the Heavy Duty Tempered Convex Jointer (300034, 300035 and 300043 to 300047)

Sizes: 300033 = 3/8"x1/2" · 300036 = 3/4"x7/8" · 300037 = 7/8"x1"

The Heavy Duty Convex Jointer is the tool that produces the standard rounded concave mortar joint, the most common finished joint in residential and commercial brickwork. The working face of the tool is convex, and it presses a concave hollow into the mortar.

The tool is a single S-bent steel bar with a half-round convex working end at each end and the size stamped into the flattened center section. There is no wooden handle and no separate grip component. The tool is held at the flattened center section, and each end is a working end.

Specify this line when the finished wall needs a plain rounded concave joint in a 3/8", 1/2", 3/4", 7/8" or 1" joint width. For a 5/8" joint, see the Heavy Duty Tempered Convex Jointer. If the facade needs a decorative center line instead, the Grapevine Jointer in the Leading Tools range is the tool; if only the three core North American widths are needed, the Brick Jointer 300053–300055 covers them.

A note on the name. Despite the name, a convex jointer's rounded face forms a concave mortar joint. Buyers also know this joint as a half-round or rodded joint, and this double-ended, S-bent style of jointer as an S-shaped jointer.

Core Features

• Convex face, concave joint: the working principle. The convex working face compresses mortar downward and sideways as it passes through the joint, so the mortar is not merely smoothed but densified against both brick arrises.
• The resulting recess sheds water. The curved hollow left behind gives rainwater a path down and out of the wall face rather than into it.
• Compressed edges seal against the brick. Because the face bears on the brick on both sides of the joint, the mortar at the edges of the groove is pressed into tight contact with the brick faces, which is where water infiltration usually begins.
• Three sizes between 3/8" and 1". Three article numbers, 300033 (3/8"x1/2"), 300036 (3/4"x7/8") and 300037 (7/8"x1"), cover the 3/8", 1/2", 3/4", 7/8" and 1" joint widths, against two for the Grapevine Jointer and three for the Brick Jointer. The Heavy Duty Tempered Convex Jointer covers the 1/2"x5/8" and 5/8"x3/4" sizes in between.
• Double-ended: two joint widths per tool. Each article number carries a different width at each end, which is the standing convention for this tool class.
• One-piece bar, nothing to work loose. With no ferrule, rivet, tang or wooden grip anywhere on the tool, there is no joint that can loosen, swell or split on a wet site.

Product Advantages

• Product Name: Heavy Duty Convex Jointer
• Art. Nr: 300033, 300036, 300037
• Joint Profile Produced: Standard concave (rounded, round struck)
• Sizes Available: 3/8"x1/2", 3/4"x7/8", 7/8"x1"
• Construction: One-piece S-bent steel bar, convex working end at both ends, size stamped at the center; no separate handle
• Position in the Leading Tools range: A concave jointer for the 3/8", 1/2", 3/4", 7/8" and 1" joint widths. Grapevine 300024–300025 = decorative center line; Heavy Duty Tempered Convex 300034, 300035 and 300043 to 300047 = five sizes, including 5/8"; Brick Jointer 300053–300055 = three core sizes only
• Why a buyer chooses concave over the alternatives: it is the default specified profile for exterior brickwork, it performs well in freeze-thaw exposure because it does not hold standing water, and it is the profile a mason can run consistently at production speed

How to Use

Using the Jointer: Key Points

• What the joint does. The concave joint compacts the mortar and sheds water. It is the most common tooled joint on brick and the usual joint on concrete block, and it suits freeze–thaw climates.
• Choose the end that matches the joint width. Turn the tool end for end to work the other width. The two figures in the size, such as 3/8"x1/2", are the two ends.
• Compaction matters more than shape. Fill the joint completely, press the mortar firmly in, and tool the head (vertical) joints as well as the bed (horizontal) joints. Many masons start with the head joints; that is a common practice, not a rule.
• Let the S-bend work for you. The S-bend keeps your knuckles clear of the wall and lets you work the tool at different angles.
• Clean up last. Once the mortar has set enough, brush off the crumbs with a soft brush.

When to Use

Basic Technique

Timing: the Single Most Important Variable

The joint is not made by the tool alone; it is made by tooling at the right moment. The trade test is thumbprint hard: press a thumb firmly into the mortar in an inconspicuous place. If the mortar takes a clear impression and does not stick to the thumb, tool now. Tool too early and the joint will not seal; tool too late and the tool tends to pull the mortar away from the unit rather than compress it.

How long that takes depends on the weather, the mortar and how absorbent the brick is, so rely on the thumbprint test rather than on a fixed time.

Bed Joints and Head Joints

Head (vertical) joints. Many masons tool these first, which is a common practice rather than a rule. Run each head joint from the top downward with the end of the tool that matches the joint width; head and bed joints on the same wall should be the same width.

Bed (horizontal) joints. Position the convex face against the mortar with the shank angled slightly up, start at one end, and draw the tool toward you: pulling, not pushing, in one smooth continuous motion, holding the angle constant the whole way. Lift cleanly at the end rather than trailing off.

One direction, one hardness, one pressure. These three consistencies are what separate a professional-looking wall from an amateur one, far more than tool brand does.

Commercial Brick Veneer

On a large commercial veneer there may be tens of thousands of linear feet of joint, all of it tooled by hand. Two consequences follow for the buyer: the tool has to survive the job, and the joint width has to be decided once and held. For a commercial package, specify the matching article number in quantity rather than one tool per crew.

Cavity Wall and Two-Wythe Construction

In a cavity wall the outer wythe carries the weather and the inner wythe usually does not. The concave joint belongs on the outer wythe, where its water-shedding recess and compacted brick-to-mortar interface do their work. Whether the inner wythe is tooled at all, struck flush, or left as laid is a specification decision rather than a tool decision.

Repointing and Restoration

Repointing is where this tool class earns its reputation. The sequence:

1. Rake out the deteriorated mortar to a sound depth and square the back of the cut.
2. Wet the substrate so the old, absorptive brick does not pull the water out of the fresh mortar before it can cure.
3. Fill deep joints in stages rather than in one pass, to avoid shrinkage voids behind the face.
4. Wait for thumbprint hardness: in repointing this is judged joint by joint, because a small patch in the sun and a shaded one will not arrive together.
5. Tool with the article number whose end width matches the existing joint, in the same direction throughout the patch, so the repair does not read as a band across the wall.

Hot and Cold Weather

Hot, dry weather shortens the window, so the mason must tool in smaller sections and check hardness more often, and should work the shaded elevations in the middle of the day.

Cool, damp weather extends the window, which allows longer runs to be laid before tooling but also means a crew that tools on habit rather than on the thumb test will tool too early and fail to seal the joint.

FAQ

Q1. Does a convex jointer make a convex joint?
A. No. "Convex" describes the tool's working face, which bulges outward; pressed into mortar it leaves a hollow that curves inward, which is a concave joint.

Q2. What do the two figures in "1/2"x5/8"" mean, and which size should I order if I only order one?
A. They are the widths of the tool's two working ends, so it forms a 1/2" joint at one end and a 5/8" joint at the other. If you only order one, choose 300033 (3/8"x1/2") or, from the Heavy Duty Tempered Convex Jointer, 300044 (1/2"x5/8"): 3/8" is the standard North American bed-joint width, and 1/2"x5/8" is the all-round pairing.

Q3. Does this tool have a wooden handle, and how do I look after it?
A. No. It is a one-piece S-bent steel bar with a convex working end at each end and the size stamped in the center; the mason holds the flattened center section directly. Clean it, dry it and keep it lightly oiled.

Q4. When should I tool the joint, and in what order?
A. When a firm thumb press leaves a clear impression and the mortar does not stick to the thumb. The time depends on weather, mortar and brick. Tool the vertical (head) and horizontal (bed) joints; many masons do the head joints first, which is a common practice. Work in sections so the whole area is tooled at the same mortar hardness.

Q5. The finished recess is shallow and uneven, or the mortar crumbles or smears. What is wrong?
A. A shallow, uneven recess most often means the convex face has worn flat in the center (lay a straightedge across it: a worn-flat face lies flat against the straightedge instead of touching only at the center); it cannot be recut on site, so replace the tool.

If the mortar crumbles, it has gone past the right moment: cut it out and repoint rather than tooling a failed joint. If it smears and sticks, you tooled too early or the tool face is dirty, so wait for the mortar to firm up and clean the face before each pass.

Specifications Overview

Convex Jointer: How It Works

The working face of the blade bulges outward in the middle. When that face is drawn along a mortar joint, it displaces mortar out of the center of the joint and packs it toward the two brick arrises, leaving behind a hollow that curves inward. A convex working face makes a concave joint.

The concave groove works for three related reasons:

1. The convex face compresses the mortar outward and inward at the same time as it passes through, densifying the surface rather than just wiping it flat.
2. The recess left behind is a drainage channel: water running down the wall face is carried across and off the joint instead of standing on a ledge.
3. The mortar at the edges of the recess is compacted directly against the brick faces, which closes the brick-to-mortar interface where water infiltration normally starts.

This is why a concave joint drains well, and why raked joints, which leave a horizontal ledge, admit more water than a concave joint.

Size Options

How to read the two numbers. The two figures are the widths of the tool's two working ends: 300033 has a 3/8" end and a 1/2" end, 300036 a 3/4" end and a 7/8" end, and 300037 a 7/8" end and a 1" end. Turn the tool end for end to use the other width.

About the Name Heavy Duty

"Heavy Duty" is part of the product name. The catalog does not state bar thickness or weight; please contact sales for these details.

Blade and Construction

Handle / Grip

There is no handle at all. The tool is a single steel bar: the mason grips the flattened center section directly, and each end is a working end. There is no wooden grip, no soft-grip overmold, no cushion grip and no ferrule anywhere on the tool.

Selection Guide

Choosing the Right Size

Start from the specified joint width, not from the brick. The first figure of each pair is a joint width the tool will finish, and the second figure is the other end of the same tool. The three Heavy Duty Convex articles cover the 3/8", 1/2", 3/4", 7/8" and 1" joint widths; for a 5/8" joint, choose an article from the Heavy Duty Tempered Convex Jointer (300044, 300045 or 300035).

3/8" is the default. It is the standard North American bed-joint width, and in the Leading Tools range it is reached by Heavy Duty Convex Jointer 300033, Heavy Duty Tempered Convex Jointer 300043 or 300034 and Brick Jointer 300053. If a customer asks for one jointer and gives no other information, 300033 (3/8"x1/2") or the Heavy Duty Tempered Convex Jointer 300044 (1/2"x5/8") is the safe first recommendation.

Match, do not guess, on restoration work. For repointing an existing wall, measure the existing joint and select the nearest end width; a joint finished with a tool of the wrong width will read as a repair line across the facade even when the mortar color matches.

Jointer Profile Selection: When to Choose the Convex

One line of that table needs a word of explanation. A raked joint leaves a horizontal ledge and admits more water than a concave joint, which is why it belongs on sheltered and interior work rather than on an exposed elevation.

Leading Tools' Four Jointers: Which One to Choose

Heavy Duty Convex vs. Heavy Duty Tempered Convex

Both lines are heat-treated and form the same rounded concave joint. They differ in the sizes they cover:

• Heavy Duty Convex: 300033 (3/8"x1/2"), 300036 (3/4"x7/8") and 300037 (7/8"x1").
• Heavy Duty Tempered Convex: 300043 and 300034 (3/8"x1/2"), 300044 (1/2"x5/8"), 300045 and 300035 (5/8"x3/4"), 300046 (3/4"x7/8") and 300047 (7/8"x1").

Full Size Reference

Complete article-number reference for the Heavy Duty Convex Jointer. All three article numbers are listed.

Selection shortcut by project type:

Related Leading Tools articles, for when a decorative joint or the Heavy Duty Tempered Convex line is needed:

Care & Maintenance

After Each Use

• Brush all fresh mortar off the tool with a stiff brush and clean water before it sets.
• Pay particular attention to the center of the convex face; it is the part of the tool that does the work and the part most often left with a film of mortar.
• Dry the tool completely with a clean cloth.
• Oil the blade lightly. Steel needs protection from moisture, and mortar is wet; a clean, rust-free face is also what makes a slick joint.

Regular Inspection

Convex profile wear: the check that matters. Lay a straightedge across the convex face. A convex face touches the straightedge only at the center, with light showing on both sides. If the straightedge lies flat against the face and no light shows at the sides, the curve has flattened and the tool will no longer form a full-depth recess. Replace it; a flattened face cannot be restored to the original arc on site.

Bar straightness. A bar that has been sprung out of its S geometry will not present the face at a consistent angle. Minor deviation can sometimes be corrected; significant deformation means replacement.

Surface condition. Pitting on the working face transfers to the finished joint. A tool left standing in wet mortar will pit far faster than one cleaned at the end of each day.

There is no handle-to-blade junction to inspect on this tool, because there is no separate handle.

Storage

• Hang the tools or lay them flat; do not stack them with working faces in contact.
• Store dry.
• For long-term storage, apply a heavier oil film and wrap the tool in a dry cloth.

Mortar Admixtures

Some modern mortars carry air-entraining agents and other admixtures that can change the color or surface texture of the tooled joint. Test on a small, inconspicuous area before tooling a whole elevation with an unfamiliar mortar formulation.