Soldering Iron Maintenance

“How do I maintain my soldering iron?  I see so many different methods online that I find it confusing.”

Regular cleaning

There at least two reasons for regular cleaning of the solder bit.

The first is to avoid the build-up of carbon and other contaminants which impedes the transfer of heat from the soldering bit to the solder and surfaces to be joined.

Many soldering stations come with a sponge which, when wet, is used to quickly swipe the iron's tip clean. A small amount of fresh solder is usually then applied to the clean tip in a process called tinning.

The second is to maintain the soldering bit in good condition.

The copper that forms the heat-conducting bulk of the soldering iron's tip will dissolve into the molten solder, slowly eroding the tip if it is not properly cleaned. As a result of this, most soldering iron tips are plated to resist wearing down under use. To avoid damaging the plating, abrasives such as sand paper or wire brushes should not be used to clean them. Tips without this plating or where the plating has been broken-through may need to be periodically sanded or filed to keep them smooth.

To avoid using abrasives, cleaning with sal ammoniac is recommended. This comes in a block. You rub the hot soldering iron bit on the surface. As the surface becomes hot, it begins the cleaning process, noted by the smoke rising from the block. When the block under the bit becomes clear, the bit will be clean and can be tinned as above. If this is done at the end of each session of soldering, the bit will last longer and will be ready for soldering immediately when you next need to use it.

Turn off the Iron

The most important element in the deterioration of soldering iron bits is long idle times. This is where you leave the iron on, and not in use, for a long time.

Have everything ready when you start soldering, so the iron will be used continuously, and will not sit there building up heat, while you get ready to use it again. An idle iron without internal temperature control will keep heating to its maximum capacity and, without anything to transfer the heat to, it will start burning off the tinning after a short while. If you will not be using the iron for a while turn it off until you are ready again.

Tinning

If a bit has not been properly tinned, solder will not wet to it. Without solder on the bit heat transfer from the bit to the work surface may become extremely difficult and time consuming, or even impossible.

You will understand that proper wiping and continuous wetting is important and a lot easier than continually having to clean and re-tin the bit, especially at the risk of damage to the plated surface because of accidentally scratching, or over abrading it.

When you notice that an iron is not performing as well as it did when it was new you will find that poor thermal transfer from the soldering bit to the work is usually the cause. Improper care and maintenance and the lack of a periodic cleaning of the bit can cause a layer of oxides to form, which will inhibit the transfer of heat through the bit.

These factors are reasons why keeping a film of solder on the bit (tinning) is important in maintaining the long life of the soldering bit.

Courtesy of American Beauty Tools

Cleaning the whole Bit.

Each soldering bit has a shank which fits into a heating collar of one kind or another.  The bit should be removed at periodic intervals and the build-up of oxides should be cleaned from the shank.  The oxides inhibit the transfer of heat from the elements to the soldering bit.  This cleaning work, of course should be done when the iron is cool.  You can use fine abrasives on the shank to remove the oxides.  You can also make a tube of fine sand paper to clean the inside of the heating collar.  This should not be done on ceramic heated soldering irons such as the Hakko.

Wattage

Another element in the maintenance of soldering irons is to have an iron of high enough wattage to readily melt the solder and be able to reheat fast enough to maintain the necessary melting temperature. An iron with enough power will reduce the strain on the heating element of the iron and the strain on the user while waiting for the iron to catch up.

For example, an 80-watt iron is sufficient to solder with, but it will continue to get hotter, as it has no temperature control, becoming too hot for stained glass soldering, and often causing breaks in the glass. An iron of this type is often used with a rheostat in order to prevent overheating while it is idling. However, this  reduces the power to the iron and so increases the time needed to recover sufficient heat to continue soldering.  Also, a rheostat only slows the heat up, it does not limit it, so eventually the iron will still become too hot if left to idle.

Most temperature-controlled irons seem to be produced in 100 watts or higher. These irons attempt to maintain a constant temperature. Their ability to do so depends on the wattage and the amount of heat drained from the bit during soldering. The temperature-controlled irons are normally supplied with a 700°F bit (identified by the number 7 stamped on the internal end of the bit) and is sufficient to melt solder without long recovery times. You can obtain bits of different temperature ratings, commonly 800°F and 600°F. The 800°F bit is particularly useful when doing a lot of copper foil soldering, because it recovers to a higher temperature, allowing much more continuous soldering action.

An increasingly popular soldering iron has a ceramic heating element, requiring less time to recover heat, and with a lower wattage.  Most of these have a temperature dial for setting the soldering temperature, and most find 410C suitable for copper foil work, although 380C may be enough for leaded glass soldering.

You can also get several sizes of tips for different detail of work.  Upon first sight a fine tip would be useful for fine copper foil work.

But fine tips loose heat quickly, requiring the user to wait while the tip regains the required heat.  A 6mm to 8mm wide bit is useful to maintain the heat during the running of a long bead.  Of course, the bit is wider than the bead being run, but the solder has enough surface tension, while molten, to draw up into a bead the copper foil without spreading – unless too much solder is being applied. Really big bits of 12mm or larger are not practical – long initial heat up times, and too much area is covered, even though there is enough heat stored for really long solder beads.

Revised3.1.25

Cutter Wheel Angles, 1

The Effects of Wheel Angles on Glass Cutting

The wheel of a glass cutter does not “cut” the glass. The objective is to create a crack or "fissure" along which we expect the glass to break when we bend it. The idea is to produce a fissure which is continuous, and of uniform depth, without creating a flaky score line full of loose glass chips. While the wheel angle is only one of several variables which influence the quality of the fissure, it is the best place to start. The other main variables are wheel diameter and cutting pressure.

The angle of a wheel is identified as the included angle to which the apex is honed. This means it is measured from one beveled face of the wheel around through the wheel to the other face. Thus the angle between the wheel and the glass on a 150° wheel will be 15° on each side.
When downward pressure is exerted on the wheel rolling along the glass, forces are created which radiate down and to the side trying to shear or separate the glass along the surface. These forces are in a downward direction with little angle to the side when an appropriate angled wheel is used. If these forces are great enough to overcome the inherent compressive conditions near the surface, a crack or fissure will be generated along the path of the wheel. The direction of these shearing forces is determined by the wheel angle.

A wheel with a large or blunt angle produces shearing forces that tend to be directed downward more than to the side. It would require a great deal more cutter pressure to create enough lateral force to overcome the compression in glass. This explains why a cutter requires more pressure as it gets older. The apex tends to flatten so its effective angle becomes greater.

With a very sharp wheel angle, the shear forces are directed more parallel to the surface of the glass. This might suggest it is easier to produce a fissure with a sharp wheel than a dull one. The shear forces are directly opposing the compressive condition near the surface of the glass therefore, requiring less downward pressure to make a crack. But a sharp wheel tends to cause chips and a flaky score. Also, when the shear forces run close to the surface of the glass they are more likely to cause a lateral crack which then breaks out to the surface, creating a chip. You can see these chips leap out of the glass a short time after scoring. Again, the compressive condition of glass near the surface literally squeezes the fissure closed, spitting out loose chips. They can be seen lying on top of the glass.

Part 2

Based on information from the Fletcher Terry Company.

See also wheel angles

Revised 23.12.24

Cutter Wheel Angles, 3

The effect of glass thickness on cutting

Most of the thicker glass being used today is produced by the "float" method. In this process the glass travels horizontally from the furnace, through a molten tin bath, through annealing lehrs, then continues on rollers where it is inspected, scored and broken into the sizes required. The thickness generally dictates how fast the ribbon of glass moves. The thicker the glass, the slower it is processed and the more effective the annealing. This applies to thicker art glass too.

The key to subsequent cutting float glass is the annealing cycle. Thicker glass tends to have less compression at the surface and tension in the interior. As a result, the glass cutting wheel encounters less resistance to producing a fissure with the shearing forces. However, this means the glass surface will chip more readily. Therefore, a larger wheel angle is required to prevent chipping. It is also common practice to use a larger diameter wheel and larger angle so the fissure can be driven deeper without chipping.

Part 1

Part 2

Prepared from information provided by the Fletcher-Terry company.

Cutter Wheel Angles, 2

Effect of wheel angles on the cut edges of glass

Another factor to consider in selecting the proper wheel angle is the "edge". The objective of good glass cutting is to produce an edge which is flat and relatively free of irregularities such as "shark teeth".

Shark teeth are the occasional deep spikes in the edge and are accompanied with flakes or tiny chips on the surface. A three mm thick glass scored with a sharp wheel (114°) will produce this effect. This edge irregularity may lead to failure during the life of a window.

A three mm thick glass scored with a proper angle (134°) of wheel, will produce a fissure that is made up of individual "hackles" which overlap one another. They have a unique semi-circular shape and indicate the direction of the cutting wheel. With proper pressure the edge will be relatively free of irregularities and without shark teeth.

Part 3
Part 1

Prepared from information supplied by the Fletcher-Terry company

revised 23.12.24

Deep inside cuts with turntable

Deep inside cuts can be assisted by using a lazy susan – a turntable affair, similar to a cake decorating turntable.

image credit: Amazon

The first question you have to ask yourself is whether you should make such deep inside cuts or redesign the piece to avoid creating such fragile shapes.

OK. You have decided to go ahead with your plan in spite of good advice. Put your cartoon onto the turntable and the glass over it. If the glass is too dark or opalescent, make a template and mark the glass. Adjust the starting point, put one hand on the glass and cartoon, and turn the glass instead of yourself to get round the score with ease.

You still have the task of breaking out the glass from the score line. This is the subject of another tip on concave curves.

revised 23.23.24

Cementing Brushes

image credit: stainedglasscraft.co.uk

Use stiff, but not hard bristle brushes for cementing. Nylon scrubbing brushes have a good stiffness without being too hard. Some natural bristle brushes are very hard and scratch the came excessively. In general, moderately stiff brushes with about 1 1/2" bristles are fine for cementing. There should be space between the bristle bunches to aid cleaning.  As they do not last very long, they should be cheap, but with firmly attached bristle bunches.

Cleaning the brushes is very simple. The action of rubbing the cement under the leads with whiting causes a natural cleaning action to take place. As the bristles flex back and forward over the came, the cement is forced upward toward the handle, and then outward between the bristle bunches. Only a little effort is required to finish the cleaning: push a rounded stick between the bunches to move out the remaining cement. You now have a clean brush for the next job.

The alternative is keeping the brush in water, but this presents the problem of getting rid of the water (oil and water do not mix) before beginning to cement. As the water will emulsify with the linseed oil, it will be carried into the putty, leaving gaps in the cement when the water eventually evaporates. The cement will eventually harden, even though in water, as linseed oil cures by creating an organic polymer through oxidisation. It can also rot the wood handles.

Keeping the brush in mineral spirits does keep the brush flexible but requires drying/evaporating the spirit before beginning the cementing to avoid the residue of the spirit creating cement that is too thin at the start. This can be a really messy problem!

If you choose the “dry” method, it is important to keep the brushes free of hardened cement as it will scratch the leads badly, if not the glass too. Most brushes will only last 5-10 uses, and as they are not expensive, should be easy to throw away.

Grinder Bit Chipping Glass

Credit: Techniglass.com

A new grinder bit chips the glass excessively, especially with a coarse grit. It can also be the result of a bare spot on the bit.  You need distinguish between these states.   Check the surface of the bit.  If there are any small bare spots, the bit needs to be replaced.

 

Credit: WWGrainger

The best thing to do with a new coarse bit is to treat it with a dressing stone.  This is a block of aluminium oxide which can remove high points on the bit, and clean up the spaces between the diamonds on the bit.  It is relatively inexpensive to buy and lasts a long time.  The dressing stone can be a brick, although it is not as efficient because it is much softer.  

If the grinding bit still chips off too much glass from the edge, you need  a finer grit.  It will not take glass off as quickly as the coarse one, but it eliminates or reduces the chipping.  The three common grades are: coarse, standard, and fine.  It is a good idea to maintain a stock of the medium and fine grit grinder bits as replacements for worn ones.

Core drill bits

Credit: JMbestglass.cn

Using core drill bits needs a drill press. It keeps the drill bit steady and avoids breaking the core which plugs the hollow part of the bit.

Oscillating a core diamond drill bit is not the correct procedure. Oscillating the bit creates two undesirable things.

• It breaks off the core that  is being drilled out, plugging the drill bit, and blocking the cooling water being pumped to the drill bit.  This means the bit heats up and loses some of the diamonds. Additionally, it can heat up the glass so much that it breaks. If you are not using a flushing head with your drill, you will need to raise the bit a little from time to time, allowing water to the grinding surface. 
• Starting at an angle or oscillating with a core bit wears out the sides of the drill bit more quickly than necessary. Core drill bits need to be applied directly and vertically. This is why core bits do best in a drill press. It holds the bit in a vertical position without breaking the core being drilled out, or prematurely using the diamonds higher up the bit.

Credit:  Lawson-HIS

There are generic drill presses available for holding Dremel-type craft motors and hand-held drills. They are inexpensive and make the drilling process so much more certain to regulate the pressure. It also makes an easier start without skipping over the glass. They are so inexpensive that a few holes without skipping will pay it.

Credit: Bhole ST1542 Pico Dril

Drill speeds should be varied according to the size of the hole being drilled. This is important with the high speed Dremel-type motors.  Larger holes need a slower speed than smaller ones. The rim speed of a small bit is nearer the rpm of the drill than a larger one, because the larger one travels a greater distance per revolution than a small one. A listing of recommended speeds is given in this blog.

Hollow core diamond bits are of two types:

•     One, where a heating process attaches the diamond, is called sintered in Europe and other countries.
•     The second, where the diamond is bound with resins, is called bonded in Europe.

They seem to have different designations in North America.

Bits of the first type are longer lasting, and more expensive. These can be “sharpened” with an aluminium oxide dressing stick to expose new diamonds and maintain their effectiveness.

Credit: W W Grainger.com

Bits of the second type wear quickly and should not be “sharpened” with a dressing stone. The normal wearing away of the bonding material exposes the new diamonds.  Dressing them wears away the diamonds that could be used in drilling.

Another advantage to core bits, is that a core drill grinds out much less glass from the hole than a solid drill bit, so it takes less time to drill a hole.

One disadvantage, especially on core drills of 5mm and less, is that the core needs frequent cleaning out of the cores that get stuck inside the drill bit. To maintain efficient and effective drilling, the core needs to be poked out from the bit from the base toward the drilling surface.  This applies whether water is being pumped through the core or not.  Without clearing the core, more pressure must be used to continue drilling, resulting in larger break outs as the hole is completed, and more breaks of the complete piece.

Home Made Frit Maker

Recently, when looking for a small frit maker, no shop had one in stock.  Having heard of making one from plumbing pipes, I went in search of material.  I came across stainless steel pipe and caps.

 

The practical size seemed to be 50mm.  Short sections of threaded pipe were available with matching caps.  That forms the containment cylinder.

 

A threaded 25mm pipe and cap can be fitted loosely into the larger one, and so forms the plunger or piston.

 

There needs to be a handle.  It could be a turned piece of wood to fit the inside of the pipe.  In this case, I obtained a reducing connector to fit a 12mm pipe to the plunger and topped it with another cap. 

The whole was put together in less than a minute, once all the parts were assembled.

The completed frit maker

Galvanised pipe would be cheaper but carries the possibility of introducing zinc into the frit.  Stainless steel risks introducing non-magnetic particles into the frit.  As I sieve out powder from my own frit making before washing, I am not too concerned about steel contamination.  If you want powder, use uncoated mild steel so the contamination can be drawn out with a strong magnet.

Silberschnitt Runners

 
The use of the highly acclaimed Silberschnitt cut runners requires a bit of experience to get the best from them.  They are at their best on inside curves and thin strips.  This is a few notes on how to make best use of the runners.

 

 
Always use the runners with the name visible to you.  This is the right way up.
 

Make use of the adjustable bar at the top of the runners.  Rotate the adjustable bar to be at right angles to score line.  This means the pliers do not have to be at a particular angle to the score line, which has advantages in tight areas.
 

Each press of the handles opens only a small run of the score.  Excessive pressure risks breaking glass and reducing the life of the pads

 

Move the runners along to the front edge of the opened score and press again.  Work your way all along the curve adjusting the angle of the bar as you go.  This progressive opening of the score line gives a break with almost no flares.
 

These runners are much better than the plastic ring star breakers, because there is much more control over angle of pressure.
 
Note: make sure you get replacement pads when you buy, they are robust but do wear out over time.).
 
 
Silberschnitt running pliers are excellent but require some experience to get the best from them.

Hake brushes

Hake (ha-kay) brushes are made from goat's hair. Their advantage over other brushes for applying kiln wash is that they hold a lot of liquid. Proper ones made from joined bamboo work better than the ones with flat handles.

Traditional Japanese hake brush

People often note that these brushes tend to shed hairs. The solution to stray hairs (given to me in a Bullseye workshop) is to invert the new brush and apply super glue at the point where the hairs emerge from the handle.  This holds the hairs in place. It will work on flat handles too.

Inexpensive goat's hair brushes of the hake style.
As can be seen by comparison, there are fewer hairs in these.

Renewing the Grinder Bit

When to replace the grinding head?

An obvious time is when the grinding becomes much slower than previously.  Adjusting the bit up or down to expose a new diamond grinding surface is the obvious first step.  When there is no more adjustment available it is time to replace the whole bit.

Another time to replace the bit is when a bare spot appears.  

One style of wear on these bits is not just the general, even wear all the way around the bit, but where all the diamonds are lost, and the metal is exposed.   

This bare spot can be observed upon inspection.  But most of us do not regularly inspect the bit before turning the grinder on.  There is another way to tell something is amiss.  What you may notice is an unexpected vibration during grinding.  When you experience this vibration, it is time to inspect the bit.  You will most likely find a patch of bare metal.

You do not have to throw the bit out.  If there is space above or below the bare spot that will provide a grinding surface for the thickness of glass you are grinding, you can do something to extend the life of the bit.

Simply raise or lower the bit until the bare spot is below the surface of the grinder grid, or in the case of this illustration, raise it sufficiently high to be above the thickness of the glass you are grinding.

Why do the bare spots appear?

It may be due to manufacture. The bonding of the diamonds may not have been completely even.  But it can also be due to grinding while there is little water – when a paste appears.  This leads to heating of the grinding bit as much or more than the glass.  A hot grinding head, especially those which are resin bonded, can lead to loss of diamonds either in one spot or generally around the bit.

Hake brush

Bamboo handle hake brush

The hake (pronounced hah–kay) brush was developed in the far east.  It has several variations – the original consisted of a group of bamboo brushes bound together in a line.  These are still made and used. Many modern hake brushes have a broad wooden handle with a wide line of hairs.  These brushes are made of very fine, soft hairs - often goat hair is used. 

Flat wooden hake brushes

The flat hake brushes are most often cheaper and in a wider variety of sizes than the bamboo ones.  I prefer the bamboo for the feel in the hand that the broad handle gives.  With the longer hairs, it holds more moisture and delivers even amounts of kiln wash even with long strokes. 

Use

These brushes can hold a lot of moisture and deliver it evenly.  This makes it good for laying  down large areas of even colour in watercolours, and in glass painting. The same characteristic makes it very good for coating shelves with kiln wash.  The brush should be filled liberally with the paint or kiln wash. The brush should be gently shaken to remove any excess. Hold the brush nearly vertical and let the bristles barely touch the surface as you move along in smooth sweeps across the surface.  This allows the kiln wash to be evenly spread with very few brush marks.

Maintenance

One drawback of these brush is that the fine soft hairs are difficult to bind into the ferrule.  This results in the brushes often shedding hairs onto the shelf as it is being coated. A tip I learned from Bullseye is to treat the new hake brush with superglue at the base of the hairs. It does not have to be super glue.  It can be any runny glue, or diluted PVA.  I prefer super glue, even though it is reported to have some sensitivity to moisture. You can work the glue into the centre by using a needle to poke at the hairs to move the glue toward the centre of the bristles.  The glue binds the hairs in addition to the binding at the ferrule, and so keeps the brush from shedding. 

I did this on my bamboo handle hake brush a couple of years ago and it is not yet shedding hairs during applications of kiln wash.

Make sure you clean the bristles immediately after using to avoid any material drying among the hairs and causing them to break when next used.  To clean the brush, you only need running water run through the bristles.  Do not scrub the bristles against anything.  The hairs are delicate.  Set the brush aside horizontally to allow water to drip off and the hairs to dry.  Setting the brush upside down when wet allows water into the bindings of the hairs.  Putting it with the hairs down onto a surface deforms the hairs, making it difficult to straighten them later.

A hake brush is among the most useful tools to put kiln wash onto shelves and moulds because it holds so much moisture.  It does require maintenance to ensure the hairs do not shed and that the delicate hairs are not broken.

Adjusting Cut Running Pliers

Typical cut running pliers

Cut running pliers are very useful tools if used correctly.  The pliers must have the curve in a “frown” rather than a “smile” to operate properly.  The knurled screw at the top and the scored line on the top jaw help place the pliers the right way up. They must be placed directly in line with the score. They should be only a centimetre or so onto the glass.  Holding them at the end of the handles, apply gently increasing pressure until you hear a click or see the score running.  If it does not run completely, turn the glass around and apply the pliers to the other end of the score.

Use of the Adjustment Screw

It is important to make use of the adjustment screw to get the best from the pliers.  If this is not adjusted properly, it is possible to crush the glass, or at the other extreme, not run the score at all.

The jaws need to be adjusted for the thickness of the glass.  The method I use for this is to place the edge of the runners on a corner of the glass to be scored.  

Loosen the screw until the glass is gripped by the jaws.  

Gradually tighten the screw until it resists your gentle pressure on the handles.  This gives you the correct opening of the jaws for that piece of glass.

When the pliers are properly adjusted to the thickness of the glass, you will not crush the glass and it is easy to use the pliers without cushions.

Rakes for Combing

It is of course, possible to buy commercial tools for combing hot glass.  But with a little ingenuity, you can make your own for a small amount of money and some effort.

My raking tool is a metre long round stainless steel rod, 8mm in diameter. I sharpened it on a  grinder for metal rather than my glass grinder. Then I bent a right angle to give me 75mm "hook". The handle is a piece of broom handle. I drilled an 8mm hole in the wood and hammered it on.

A longer metal and shorter wooden handle works better than the one I made with a long wooden handle, as there is no wood near enough the heat to burn. If you do have a long handle,  soak it in water to keep it from burning.

It is possible to make a rake using mild steel rod, but it is more likely to spall and drop flakes into the glass.  Both metals need to be kept cool.  Rest the rake in a bucket of water before the first pass at combing.  As the glass stiffens and you need to wait for the glass to come back to a combing temperature, put he rake back into water to cool it.  If you try to comb with a hot rake, it will stick to the glass.

It is important to have a handle made of an insulating material to avoid any possible electrical shocks.  It also makes for a more comfortable handle that does not heat up.

Safety gear is required to protect eyes and clothing from the heat.  It is not possible to have the kiln open at around 900C without it.  This is the face, hand and arm protection I use.  The coated visor protects your eyes against the infrared radiation from the kiln.  The gloves can be the aluminised silver colour ones or the kevlar ones.  The alminised ones are easier to manipulate things with.  The arm protectors are aluminised too. They are easy to put on and give additional safety to the body.

Natural fibres should be worn to avoid clothing bursting into fire.  I use a denim jacket reversed for additional chest protection.

Soldering Lead Came

Soldering lead came is different from soldering electronics or copper foil. For electronic soldering less heat is needed, cleanliness is all important, suitable flux is required, and the iron is held differently, among other things.

Soldering lead came The lead needs to be clean and bright to start with. If it's fairly new lead it should be solder-able without more than a scrubbing of the joints with a brass wire brush. However, if the lead is dull and oxidized, you should scrape the lead in the area to be soldered with a nail, the blade of a lead knife or other sharp edged tool until the bright metal is revealed.

an example of paste flux

Example of a tallow stick.  It has the appearance of a candle, but without the wick.

Example of the application of tallow to a joint

Then the flux can be applied.  Paste flux or tallow works best as neither flows in its cold state.  This means that you can flux the whole panel at one time without the liquid flowing away or drying.  Once the whole panel is fluxed, you do not need to stop during the soldering process.

Example of a gas powered soldering iron. The flat face of the soldering bolt is held in full contact with the joint.

An electric soldering iron is held over-handed (as you would a bread knife) in order to get the handle low enough to have the tip flat on the lead. This will be a 15 to 20 degree elevation from the horizontal. Allow the weight of the soldering iron to do the work for you. 

Let it rest on the joint after you apply the solder between the lead and the iron. In order to heat both pieces of lead you may have to rock the tip slightly to contact all leads being soldered. Take the solder away from the iron so it doesn't become attached to the joint. As soon as the solder spreads, lift the iron straight up. This process will take only a few seconds, much less than 5.

Example of smooth flat solder joints.

Avoid "painting" or dragging the iron across the joint. The object is to have a shiny, smooth, slightly rounded solder joint. Moving the iron and solder around does two things.  It makes for a weak joint as the solder does not have the chance to become stable and so forms a "pasty" joint.  Moving the iron around during the soldering of the joint often provides sharp points where the iron was moved quickly off the join. There should be no points sticking up from the solder joint. If a solder joint is not satisfactory you can re-flux and re-heat. Don't apply too much solder. It's easier to add more solder than to remove excess.