I always get the words mixed up, but I believe there is a modern proverb that goes something like; "Neccesity is the mother of invention."  Sounds good even if its not the right phrasing.  And I think more to the point is how true the sentiment is.  The other day I was warping a rather large project on my PVC loom, and somehow or other, about four of my warp threads ended up being a yard too short.  I could hazard a few guesses as to how it happened, but the how it happened at the time was not nearly as important as how in the world I was going to fix it.  My first impulse was to just cut my losses and make my warp a yard shorter than planned and cross my fingers I included enough warp waste in my calculations.  That seemed very risky, though.  Especially since I was planning a lot of weaving on this warp- it would be awful to get to the end and be just short of a complete project.  
Then, my husband pulled out his phone and did some internet magic. (He is really good at that.) As a sat, aimlessly staring at the problem, he asked;
"What's a weaver's knot?  It looks like it could help."  I love that man.

A weaver's knot is pretty much magic!  It solved my too-short-warp-thread problem with such ease, it was almost unreal.  And the beauty of this particular knot is that you add length to your thread and the knot simply gets tighter under tension.  You don't have to worry about it slipping about or coming undone.  How awesome is that?  And I did complete the beast of a project I was working on, and the knots did their job without fuss.  I will say that the one consideration is the reed.  You want to be careful as the knots need to pass through your weave if the thread was a tight fit in the reed.  I had to manually push a few of them through, which took some time until I got past them.  But really, even though it added time to the weaving process, it saved me a ton of time from having a project that did not work out quite right. 

Here is how to make this wonderful knot:

1. In the thread that has come up short on you, make a standard slip knot.  Do not pull it tight yet.  You do not have to leave a long tail, the knot is suppose to be so strong you can clip the tails right off when you're done.  I left tails on mine and wove them in because I'm a scaredy cat.  In my example, the thread being lengthened is yellow.

2.  Thread your new yarn through the loop of the slip knot.  Again, you should not have to leave a long tail as you thread the new yarn through the loop.  However, you can leave a tail long enough to weave in later if you're nervous (like me).  In my example, the new thread being used to extend the yarn length is blue.

3.  With the new yarn threaded through the slip knot, pull the slip knot tight by pulling the two yellow thread ends.  Once it is secure, pull a little more.  You want the slip knot to pull your new thread through the twist of the knot.  I have shown both when the slip knot is pulled tight and then once the new thread as pulled through the knot.  I have found that the thread makes a satisfying little popping noise when it makes it through the knot.  This pull-through is what gives the weaver's knot its power, because as you pull, the knot now only tightens on itself.  In my example, you can see the little peak of blue looped through the yellow knot in the completed weaver's knot.

4. The knot is not complete.  The yellow portion of the thread is the yarn that needed to be lengthened.  The blue portion of the thread is the new extension to your yarn.  You will have a tail from the old thread and a tail from the new thread.

Direct Warping
The simplest and most...well...direct way to warp a loom is the direct warping method.  This method has a lot going for it.  It does not require a lot of equipment, it's perfect when you do  not need a lot of warp length for a project, there is little risk of your warp threads getting tangled, and it can be used on any loom, though I think it lends itself better to rigid heddle looms.  It is particularly nice when you have a lot of warp color changes on a small warp space.  I will describe the technique and then outline a few of the pitfalls, too.  

Brief Description of Method
With the direct warping method, you use your loom's back beam and a peg to do your warping.  You measure from your back beam toward the front of your loom and continue measuring until you get to the spot that is equal to the length of warp you desire.  At this measured spot, you clamp your peg.  For example, if you want to make a warp that is three meters in length, you would measure straight from your back beam (in the direction of the front of your loom) out three meters in an unobstructed path.  At the three meter mark, you would secure your peg to, well, something.  I've used step stools, the edges of tables, bookshelves; it's really whatever is either currently in that spot or something that you can move to that spot and be confident it will not easily move from that spot.  I would say this technique is much easier with rigid heddle looms, as you can move these smaller, lighter looms around to more convenient locations for peg clamping.  However, you also need to secure your loom!  You don't want your loom to slowly inch its way across a table while you're warping it so that you last warp threads are a foot shorter than your first warp threads.  Many rigid heddle looms come with clamps (for both the loom and the peg) and a peg, as well as detailed instructions for this method.

With the direct warping method, you secure your warp thread to your back beam, make a small loop around your finger and pull the thread toward your rigid heddle or heddles in the shafts of your loom.  Using your warping hook, you pull this looped thread through either a slot in your rigid heddle or through a heddle in the desired shaft of your loom and continue pulling until you reach the peg.  You place the loop around the peg.  You should then have what looks like two threads running from the back of your loom to your peg.  Walk back to your loom, and this time making sure to pull from under your back beam, repeat the process with another loop around your finger.  *This would be the method if you want one thread in each slot and hole of your rigid heddle.  You warp all the slots, wind your warp on your back beam, then cut your loops and move one of the two threads in each slot to the hole adjacent it.  It takes a little more planning if you are using a loom with shafts- you will need to plan on which heddle in which shaft should remain empty for you to later move the warp thread.  You would need to leave these heddles empty as you move across your warp, even if you are changing shafts with your loop.  To be honest, I have never used the direct warping method with a four-shaft or greater loom.  You would also need to make different plans if you want more than one thread in each slot or hole in a rigid heddle.  (Like if you are holding your thread double for the warp, you would need to warp the slots AND holes as you walked back and forth from your loom to the peg.)

Things to Keep in Mind
This is the quick and dirty explanation of the direct warping method.  Like I said, it is really great for rigid heddle looms, you can easily make warps with more than one color and it's great exercise.  However, there are some pitfalls.  Once you start warping, you sort of need to finish.  That is unless you have a space in your house where threads three meters in length strewn across the room don't get in the way.  Also, small children tend to like to tangle themselves in these warp threads.  It is not the easiest way to warp a floor loom or a loom with multiple shafts, though it can be done.  It is great for smaller projects, but I would caution using it for very large projects that have a lot of warp threads.  All of your threads need to fit on your peg, and when you start to get in the 300's for warp thread count, it can get crowded. (Not to mention walking back and forth for 300 warp threads can be a lot.)  Also, if your peg or loom moves, you'll have a little trouble on your hands.  Not insurmountable, but it is something to pay attention to.  

This is a method for immediate warping on the loom.  The really nice thing is that once it is measured and threaded, you can get straight to weaving. The warp threads are measure right on the loom, so there is no transfer of warp threads in this method.

Indirect Warping
Indirect warping is when you measure your warp out using something like a warping board or warping mill and then move this measure warp from your board or mill to your loom.  You can use this method to measure out warps for multiple projects and store the warps for a later time.  Typically, you can take your time measuring the warp threads because they are nicely contained in a smaller, more compact space.  I have a tutorial on using a warping board.  Warping mills work in a similar way but reduce the amount of reaching because they spin, therefore reducing the demand of movement from you.  The indirect method can be used easily for any type of loom.  I also have a quick tutorial on warping a small rigid heddle loom with the indirect method and plan on making one for a four-shaft loom as soon as I finish my current project.  This method is really nice for super long warps and also for warps that have a large number of warp threads.  This is my preferred method of warping, though I certainly use the direct method, too.  

Brief Description of Method
I will be very brief here, as there are various ways to warp a loom using this method because the warp threads are free to be moved.  Some people enjoy warping from the back of their loom to the front, and others like going from the front to the back.  I'm a front to back kind of gal, but one method is not better than another, it's just preference.  The key points that make this an "indirect" method are these: 
With the indirect warping method, you measure out your warp threads ahead of warping your loom.  It can be intimidating at first, but once you try it out, it is really a great way to warp a loom.  Let's say you need seven meters of warp.  Using your warping board, you find a path that is seven meters long without doubling back or crossing the path on the board (or mill).  Then, you grab your warp thread and go to town moving up and down this path.  (You create a "cross" at one end; please see my tutorial for warping boards for more details on this.)  A trip down your path is one warp thread, a trip back up is another warp thread, so each completed trip gives you two warp threads.  You tie choke ties in the necessary places along your measured warp, then carefully removed it, braiding it as you go.  This braided, measured warp can then been stored for later use or carried to your loom to begin the actual warping process.  

Things To Keep in Mind
The start-up for this method is a little more costly, as warping boards and/or mills can be expensive.  You can find alternative means to the commercially available options- people have made bookshelves, the bottoms of chairs and paint cans into warping boards.  My husband actually made my warping board, saving us a few bucks and adding a ton of sentimental value.  A quick search on the internet can give you some ideas on creative alternatives to the "official" boards and mills.  This method also creates a little more waste in your warp threads, as the warp has to be tied on both the back and the front of your loom, so keep that in mind when planning your final warp length.  Sometimes, particularly on rigid heddle looms that you have planned shorter warp lengths, smaller warp thread counts, and simple weave structures it is easier to just use the direct warping method.  Also, attention has to paid to that cross I mentioned earlier when you actually do sit down to warp your loom.  If you mess up the cross, your threads may get tangled in the most hopeless of fashion.  That means if you have very large bundles, you need to be prepared to sit and warp that bundle...don't put it down!  In my house, large bundles are impossible because as soon as I sit down, some emergency happens and I need to get up.  To get around this, I make small bundles, even if my warp is all one color.  This reduces the amount of time I need to sit in front of my loom- I can warp a lot or a little.

I hoped this cleared up some terminology.  Don't feel constrained by the categories, though.  I have seen people use warping boards fastened to tables to do direct warping!  So clearly, with a little imagination, there can by hybrid methods that work for you.  

Warp speed ahead!

I think many of us who have delved into the world of rigid heddles are very familiar with the direct warping method.  Using a peg and measuring from your back beam to some chair or stool or odd object you can clamp that peg to, you walk back and forth and feed your thread in loops through the slots of your heddle.  Then, you wind that bad boy up, clip the ends, distribute your threads to the holes as well as slots, tie on the front apron rod, work on your tension and call it a day.  However, this is not always the most practical way to warp your rigid heddle.  Don't get me wrong, it is a great method, but sometimes having a line of yarn strewn across your kitchen just isn't going to work.  Or sometimes you have time to measure out warp threads but you don't have time for all the threading.  Whatever the reason, you can use your warping board for your rigid heddle loom and pre-measure and prepare your warp threads.  I have a tutorial on using a warping board, so if the concept is new for you, please take a look here.  

In this tutorial, there are two colors that have been pre-measured and braided for this project.  

The next step is to wrap these braids onto the front beam of your loom.  This yarn is the warp for a cowl.  It is a bulky yarn and the braids are not very long. If I tried to wrap the braid around the front beam, it just wouldn't stay.  In cases such as these, it is okay to unbraid your warp thread and wrap them around your beam that way.  If you have measured a very long warp or used a fine thread and your braids are long, it may keep things tidier to just leave them in the braids when you wrap on your front beam.  VERY IMPORTANT: Your cross should be free from the braid with enough slack to reach your heddle in the neutral position, plus a few extra inches so when you thread your warp through the heddle, it will stay put and not try to fall out back toward the front of your loom and undo all of your hard work.  I am warping two colors in this project, and both colors could be wrapped comfortably on the front beam without overlapping.  If you find things are getting crowded or confusing, just wrap one braid at a time.  Note that the cross is draped comfortably over the heddle.  

Make sure you have all your supplies within reach.  To warp your heddle you will need scissors and your heddle/reed hook to sley your reed.

Next, pick up the cross from a braid and thread your fingers through the loops where you have your choke ties.  You will be undoing those ties, so you want to make sure your fingers will preserve the cross even after these ties are gone.  I have taken a photograph to show how I place my fingers comfortably through the cross. You will want at a finger between the top to ties above the cross and a finger between the bottom two ties below the cross.  If you are right-handed, as I am, I hold the cross in my left hand.  I am not left-handed, but I would imagine things might be easier if the left-handed crowd holds their cross in their right hand.  Really, you should do what is most comfortable for you.  Whichever hand is left free from the cross is the one that will be threading the reed and manipulating the reed hook.

With your cross secure on your fingers, take your scissors in your free hand and cut the top loop (highlighted in the photograph my finger- please note that I am not preserving the cross here, merely showing which loop you should cut).  Then, while still holding your cross secure, untie or cut your choke ties.  

Notice that once the choke ties are gone, you can still see the alternating ups and downs of your cross.  At this point, you are ready to start sleying your reed.  Starting with the outermost warp thread on your finger, use your free hand to remove it from the group (without disturbing your other threads).  I like to sley my reed from right to left, but I do not think it matters what side you choose to start on, as long as you have measured out where your project is centered in your reed.  I am sleying my entire reed, so I could start on the edge.  If your project is smaller than your full reed, you may want to mark the slot with a piece of tape where the edge of your project should be.  That way, you will easily find it when you go to warp and will not have to count or measure, which is hard to do when you have a bunch of loose threads in your hand.  

Taking the outermost thread on my cross, I use my hook and thread it through my read.  Unlike the indirect method, you will need to thread slots and holes as you go, not just the slots.  Passing your hook from the backside to the frontside (through a slot or a hole) of your reed, grab your thread and pull it through the reed.  I like to hold my hook pointing down, I find it easier to grab my warp thread this way and pull it down and away on the backside of the reed.  This is a personal preference, you should find what is comfortable for you.

Now, my pattern required that I warp my reed in a 2x2 pattern.  So, after threading two teal threads, I needed to leave space for two white threads.  You warp all of one color first and then go back and warp the second color.  (This would apply to three or more colors, as well.)  Really, you want to warp all the threads in your braid, because the cross is what is keeping your threads organized.  If you put your threads down, it is very hard to maintain the cross.  This also means you should plan ahead.  Either allow yourself enough time to warp all the threads in a larger braid or make yourself smaller braid bundles...even if you do more than one braid in the same color.  Having smaller braids will give you more opportunities to take breaks when your warping your loom without having to worry about tangling threads.

Leaving spaces can make your eyes cross, so make sure you check regularly that you have left the appropriate number of slots and holes.  It is much easier to fix a mistake when it happens than to have the majority of your reed threaded only to find out you need to shift everything over a slot.  As you can see in the pictures, two threads mean one slot and one hole.  So between every teal pair, I needed to leave one slot and one hole for my white warp.  I made sure to stop and check my work every few pairs.

Once I have warped all of my teal threads, it is time to warp the white threads.  I repeat the same exact process, threading the white warp through the slots and holes I left for them.  If you are using more than two colors, it may be useful to keep a diagram and mark with painters tape the slots and holes for your second color before you pick up the cross and begin sleying.  

Once you have warped all your threads, looking at your loom from the backside, you will see your beautiful warp threads dangling through your reed.  It is time to tie them onto your back apron rod.  Make sure you grab bundles of yarn that are only about an inch.  I know its a lot of tying, but it will give you more balanced tension.  I like to use a square knot and a bow when tying on to the apron rods.  I know my mom likes to use a surgical knot.  Whatever you use, make sure it is secure under tension but adjustable if needed.  (I would never recommend a double knot.)  

I think this is the point where there are more stylistic differences when warping.  I will share with you what I like to do, especially if I do not have a helper.  Sitting in front of your loom, grab all of your warp threads in one hand.  You use this hand to pull the threads for even tension.  Make sure you have paper or sticks ready so you can wind them in as you pull your threads over the back beam.  (If you are unfamiliar with this, putting paper in between the layers as you wind your warp helps maintain more even tension.  It prevents your threads for sinking into previous layers or catching.)   Then, slowly, begin winding.  Use your free hand to move your crank as you hold the warp threads with even tension.  The threads should pull out of your braid evenly and remain orderly.  If you need to stop cranking and gently comb some threads, do so, but remember your reed will act as a comb, as well.  Continue this process until you have wound nearly all of your warp to the back of your loom.  You will want about 15 inches of warp thread on the front side of your reed so you can comfortably tie on to your front apron rod.  You will notice that the ends of your warp are looped, you will have to cut these before you tie onto your front apron rod.  I do not recommend cutting them before you are ready to tie on- they are a bit of a security check, your threads cannot pull through your reed when they are looped.  

You're nearly finished!  Tie on to your front rod starting in the middle and alternating from there to the left and right sides.  You want to tie your warp with as even tension as you can manage.  This means once you have everything tied on, you may have to go back and tighten your threads again.  With this in mind, tie your square knot first and once the tension is even go back through and make your bows or surgical knots.  Then, believe it or not, you're ready to weave.  I was a dodo and completely forgot to take a picture of the finished warp- but here is the project that I started weaving.  Proof it does work! 

7.  In my example, I wanted the medallions to be across my entire project.  (I worked out ahead of time what size medallion would allow me to achieve this without being left with a less-than-full-sized medallion at the end of my row.  Word to the wise, plan your medallion sizes according to the number of warp strings in your project.) For the last medallion, I snuck my crochet hook up through the fifth and sixth warp threads in the medallion instead of after the sixth warp thread.  This way, I could create the loop, even at the end on my selvage.  

8.  If you wish to stack medallions, after you have completed your first row of medallions, change sheds, and pass the contrasting color shuttle through, end to end, to create a new bottom medallion border.  Then, change your shed again, and pass your main body color through for the number of picks you wish to include in your medallions.  Proceed as shown above to create a new row of medallions.

You can have a lot of fun with these medallions and they are surprisingly simple for how complicated they can look.  Try using a larger weft thread for your medallion borders, play with your medallion sizes, stack them all over your weaving or just keep it simple for a nice border.  Playing with colors can be fun, too.  Go crazy!  It is a really nice hand-manipulated weaving technique that can add some spice to an otherwise plain weave.   

*Notes:  Your drill battery will run out fairly fast.  Drills are not really intended for high-speed continuous use, I don't think.  To remedy this issue, it is handy to have a second battery for your drill charged and ready to go...just in case.  Also, it does not really matter if you use the drill set to forward or reverse, but whichever direction you choose, you should keep it the same for the whole bobbin.  (Otherwise you will start to unwind your wound bobbin, and that is not at all what we want.)  Lastly, do not use a double pointed needle that is particularly expensive or very special to you, your drill may leave little marks on it.  It will still be functional as a needle, but I would hate for something you care about to be damaged in this process.  Pencils really do work fine.  

I am excited, this is my first weaving tutorial!  And it is about using a warping board, which is something that intimidated me for a long time.  When I first got my rigid heddle loom, I was quite happy to wait until the kids went to sleep and use the warping peg to measure my lengths of warp.  (This is a direct warping method, unlike the use of a warping board, which is an indirect method.  Indirect methods allow you to prepare your warp threads and then warp your loom at a later time.) However, after my husband made my four-shaft loom for me and I started in on some more elaborate weaving, it did not seem practical to rely only on my little peg to get me through.  300+ ends is a lot for a peg.  So, my darling husband made me a warping board and we mounted it on the wall in the family room so I would have easy access while still hanging out with my kiddos.  It's a strange feature for the wall, I am sure guests do not understand what it is- either some modern art or a strange torture device.  Tell them it's a "warping board," their doubtful looks do not improve.  

Now, you do not need a large warping board nor do you need an "official" construction.  I've seen people use chairs flipped over, pegs on a bookcase, really anything where you can make a cross and find a pre-measured path (we will talk about these things in a moment).  I will say that having a warping board is nice, though.  Ideally, it is a yard (or meter) from one peg across to another peg.  Mine is not. My sweet husband got so focused on making nice joins, he didn't think about the practicality of maintaining exactly a yard between pegs until it was too late.  But it matters not!  I love my warping board- as long as you can find a path, you do not need exactly a yard or meter between pegs.

Anyway, long story short, a warping board is super easy to use and it was silly that I avoided it for so long.  I warp my loom from front to back, so I can only say with confidence that this method is full proof for preparing warp for that method.  So, let's get going.

1.  Figure out how long your warp needs to be in addition to how many ends will be in your project.  This information is readily available in weaving patterns and there are equations you can use if you are creating your own project.  Once you have established this information, you are ready to get started.  Measure out a piece of scrap yarn that is your prescribed warp length.  (I like to use a bold color so it's easy to see.  You can even label these guide threads for later use- especially for the common length warps.)  You will be making loops on either end of the thread, so make sure you give yourself an extra couple of inches before you cut.  Secure one end of the thread to a peg on your warping board, it doesn't really matter which one.  Once this is done, you might have to play around a little bit to find where to secure the other end.  Wind the thread around the pegs on your board until you get to the end of your measured thread and that end is at a peg.  Also, do not double back or cross over any part of the thread that is already on the board. When you find a path that works, tie the the end of the guide thread to the peg that it lands on by making another loop.  (This is where a board that is 1/2 yard or 1 yard across from peg to peg comes in handy.  Let's say you need three yards of warp.  Your path would be obvious.  You would simply work from one peg to the one across the board three times.  For fractions of warp length- like three and three quarters yard- or if your warping board is not a yard across, you might have a more unique looking path and that's okay.)

2.  I like to establish where my cross will be right from the start.  With this in mind, wherever I tie on as my starting peg I make sure to go under the neighboring peg and then back over top the third peg.  This is illustrated in the photograph below.  If you follow my red path, you can see it starts on the peg all the way on the right, travels under the middle peg, then goes over top the third peg on the left.  This will act as a reminder for you as you measure out your warp.  Some people like to make their cross at the end of the guide thread.  That's fine, too.  It just needs to be on one end or the other- don't try to make it in the middle.  

3.  You're now ready to start with your warp thread.  Tie your warp thread onto the first peg.  Then, follow your guide thread with your warp thread.  Notice below that I make sure to follow the guide thread under the second peg and then back over the third thread (just as we did with the guide thread in step 2).

5.  I have referenced the "cross" an number of times in this tutorial.  What is it?  Well, it is the crux of this warping method.  The cross serves to keep your warp threads neat and untangled as you sley your reed.  Especially with a large number of ends, without this cross, your threads would get hopelessly jumbled.  What the cross does is order your threads one over another so you can peel them off in the proper order.  So, to make your cross, think of a figure eight.  Remember that one peg we went under on the way down the warping board?  Well, on the way back, you will need to go over that peg then under your starting peg. Go around your starting peg, and just as you did the first time you journey forth from this peg, follow your guide thread under the second peg.  Every time you leave your starting peg you will go from the top of the peg to under the second peg, every journey toward your starting peg you will go from the top of the second-to-last peg to under your starting peg.  This is illustrated in the photographs, but if you keep the number eight in mind, it will help.  (If you put your cross at the end of your path, you would make these same motions on the second-to-last peg and the last peg of your path.)

8.  Find some scrap yarn that is a contrasting color to your warp thread.  You want to make sure you can clearly see what is a tie and what is a warp thread...it is a sad day when you accidentally snip a warp thread.

9.  You will make a total of five choke ties on your cross to maintain its integrity.  First, you make a horizontal tie around the X of your tie, as shown below.  You want to make it snug, but not too snug that you cannot snip it away.  If you know no curious little finger will mess with your ties, you can tie secure bows so that you do not need to worry with scissors.  Once this horizontal tie is made, you will want to secure all the legs of the X with four additional ties.  These five ties are best explained in the photographs below.  

10.  Next, it is helpful to make choke ties at least every yard (or meter) along your warp length.  I like to make little bundles in these ties- like the kind you see in hanks of yarn.  This isn't really necessary, you can just tie the great big bundle together, but I feel it keeps things a little tidier for me.  

11.  Your now ready to take your warp threads off the warping board.  It might be a bit snug, but wiggle the end without the cross off the peg.  Tie this end loop in a simple overhand knot while keeping the rest of your warp on the board.  

12.  From this end that you have pulled off the board, you will make a loop and then begin a chain of your warp threads through this loop as you pull the warp from the warping board.  If you are familiar with crochet, you are really crocheting your warp threads using your hand.  So, you make your initial loop, as shown in the picture on the far left below.  Hold this loop in your left hand.  With your right hand, reach through this loop toward the unchained warp thread, as shown in the middle photograph below.  Grab the warp threads and pull them through the previous loop to create a new loop, as shown in the photograph on the far right.  Repeat this process until you have chained all of your warp.