MerNetwork FAQ

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How do I make a tail?

See our list of popular guides here to find many excellent tutorials and pointers to information on this forum. Additionally, this FAQ contains answers to many popular tailmaking questions. For questions you can't find the answer to in the guides or FAQ, you can also post your questions in the forum.

What kind of tails are there?

Tails are often classified by the method used to create them. By one classification, they could be broken down into fabric tails, homemade realistic tails, and commercial molded tails. Alternatively they are often classified by the material used- i.e. spandex tails, silicone tails, ect. Fabric tails are made by making a pattern to your measurements and to whatever shape you’d like the tail and fin to be, then cutting fabric, usually a form of spandex or neoprene, to that shape. Then the two sides of the tail are sewn together with a monofin you purchased (or made) inside the fin. The tail can then be painted or decorated however you’d like! Homemade ‘realistic’ tails are a bit more difficult and are generally made by the dedicated and somewhat more advanced amateur crafter. The general process begins by making a fabric tail then covering it with a rubber compound, generally a form of latex or silicone, and using various techniques to imprint a scale pattern. The compound is left to dry cure for a time and is then airbrushed. The result is a more realistic looking skin and scale pattern, which does a generally better (but not perfect) job of hiding the knees and legs of the wearer. These sort of tails are a way for the dedicated crafter to get something close to the tails you see on television and in the movies at a lower cost than purchasing a tail from a professional tail maker. Commercial or professional-grade realistic tails are made by a process that’s generally out of reach of the amateur tail maker, requiring advanced techniques, expensive materials, specialized knowledge, more safety precautions, and generally more space than the home tail crafter can provide. Professional tails are made using pretty much the same process as television and movie tails, and many professional makers are trained in Special Effects construction and mold making.

Can someone help me make a tail step by step over the internet?

Unfortunately not, people tend to be busy and it’s unlikely anybody on the forum will just teach you how to make a tail just because you ask. Fortunately, people here who make tails probably learned how to make tails here, so the same resources they used to learn are available to you too!

How much does it cost to make a tail?

Fabric tails generally cost around $100, but this depends on the fabric and monofin you choose. The monofin accounts for the majority of the cost- the Rapid, by Finis, is one of the most popular monofins available, and costs $90 plus shipping and handling. One of the most affordable monofins is the Finis Wave, which retails for $50. Be aware that all finis products can be purchesed at a discount by using the code "mermaid20" when ordering. The remainder of the cost of making a fabric tail goes into the fabric and thread. This does not include the cost of tools and supplies, such as scissors or a sewing machine. More complex designs can cost hundreds of dollars based on the materials. Realistic latex tals can cost up to $500, and homemade realistic silicone tails are considerably more owing to the more expensive material used.

How do I measure for a tail?

Measuring for your tail is very important. In general, the more measurements you take, the better your tail will fit, and ultimately the better it will look. The basic method involves finding the circumference around your legs in various places, but its easier to show than to describe. Here is a segment from Mermaid Sasha’s tail making video that deals with measuring: Mermaid Sasha's popular tailmaking video

What precautions should I take if I am allergic to latex?

If you’re allergic to latex, you can still make a fabric or silicone tail, if that is in your capabilities. Consult with your doctor and bring the Materials Safety Data Sheet (MSDS) of the material you’re considering.

How long does it take to make a latex or silicone tail?

A fabric tail can pretty easily be made in a day, depending on if you want to paint it or what other decorations you do. The time needed to make an ALEX-type tail is going to depend on a number of factors, most notably the thickness of the scale layer, which will directly impact cure time. Depending on thickness, it can take from a few days to up to a month to fully cure.

What is ALEX Plus?

ALEX Plus is a form of household caulk, a building material used to seal cracks and gaps in things (like around sinks or in showers) against water. It is a thick paste that comes in a tube, made of a combination of acrylic latex and silicone, with some other chemicals. Mermaid Raven found that it could be used as a covering material to make a homemade realistic tail, and with a lot of early testing by Capt Nemo and members of, developed a technique to do so. It can be found in almost any hardware or building supply store.

Is ALEX safe to use for tail making?

Yes and no. ALEX and other caulks are what are known as tin- or condensation-cure silicones (and not skin-safe special effects grade ‘platinum cure’ or ‘addition cure’ silicone) The material isn’t considered safe for prolonged contact with the skin, but when we use it to make tails, it’s applied on top of a fabric base, so skin contact is minimized. This is both for safety and necessity, as the cured material isn’t strong enough to form sheets by itself without the support of the fabric. When we use ALEX to make tails, we’re using it outside of the manufacturer’s recommended/intended application of the material (See the manufacturer's Material Safety Data Sheet (MSDS) here ). ALEX and other caulks contain things that are generally considered bad for you, including formaldehyde, crystalline silica, and the main chemical in automotive antifreeze. That said, these chemicals (with the exception of silica) are water soluble, meaning they will leave the tail as you swim in it. This means that the material will be most toxic while wet, that is, when you’re working with it, so precautions should be taken then. You need to wear gloves and an appropriate mask when working with caulk, and be sure to wash up very well when you’re done. You must also work only in a well-ventilated area.

What are some of the problems with using ALEX in tail making?

This technique is still relatively new, and we’re still learning about it. This should be reason enough to consider not using it, but again, the risks can be minimized, so use your own judgement. Aside from the safety issue, there are other problems as well. ALEX is specifically not meant for applications with prolonged water contact, or use in the water. This means that given enough time in the water, it will turn white and begin to fall apart. There are ways to minimize or prevent this, but so far there is no perfect solution. Given enough time in the water over the course of its usage life, your ALEX tail will fall apart. Another problem, present in some forms of professional tails as well, is that the material is not very strong. Scraping it on rough surfaces like pool decks (or textured pool bottoms) or rocks will cause the surface to scuff or tear. There isn’t much you can do about this besides be careful with it.

So what’s the verdict on ALEX for tail making?

MerNetwork is reluctant to 'officially' endorse ALEX for use in tails, though its drawbacks appear to be relatively minor. It’s not an ideal material, has some problems and potential health risks, even if these risks are fairly well mitigated. In an ideal world, we’d have something better for the casual enthusiast to bridge the gap between fabric tails and professionally made cast tails, and with any luck somebody will discover something the way ALEX was uncovered. Until then, these caulk products are among the best options available, for better or worse.

How do I prevent my ALEX tail from degrading?

The best solution we have right now is to periodically spray your tail with a marine silicone spray like this one: McNett spray This spray will also prevent the tail from sticking to itself. You will need to apply it periodically through the life of your tail. Important: This spray is very slippery and will get all over everything. Only apply it outside where it will be safe.

What is “GE Silicone II”? Can I use it to make a tail?

“GE Silicone II” is the brand name of another form of caulk like DAP ALEX Plus, and is composed of almost entirely silicone plus some other chemicals. It is attractive to home tail makers as it can, at least in theory, bridge the gap between latex tails with imprinted patterns, and more advanced silicone designs. While the amount of experimentation done within the community using this product has been limited, many people are disinclined to use it since the material is still different from what a professional cast tail uses, and it has the same safety concerns and drawbacks as the Latex+Silicone caulk. While it is a great deal stretchier and more durable than ALEX, as well as 100% waterproof, it’s also much more expensive. Also contributing to reduced interest in GE Silicone II is the growing popularity of an alternative silicone product known as Dragon Skin. “GE Silicone II” and similar are still tin- or condensation-cure silicones, and are different from skin-safe, special effects-grade ‘platinum cure’ or ‘addition cure’ silicones. This material puts out a lot of acetic acid (vinegar) while it cures, so you should only work with it in a well-ventilated area, and as always, wear a mask and gloves.

I found a product that says it’s safe for use in the water (‘below the waterline’) for boats. Should I use it?

NO! While you can check the Materials Safety Data Sheet, in general products made for use on boats are very toxic and should never be used.

What can I use to make the scale pattern on an ALEX-type tail?

To make the scale pattern on an ALEX-type tail, a material is pressed into the rubber as it is curing, and then removed, leaving the pattern embossed in the tail. In the past, people have used fish nets (Be sure to wash them if you buy used!), metal grates, plastic mesh, and plastic snow fence, among other things. Part of the fun is finding something new and unique to use!

Can I glue two layers of fabric together?

You ‘can’, but there’s really no good way to, and it will create pockets that will fill with water. Generally avoid designs where gluing (or sewing) two large sheets of fabric together to form a single layer.

What can I use to glue neoprene?

Use a specialized adhesive like McNett SealCement

Can I sew neoprene on my sewing machine?

In general yes, with some special techniques and material. Because neoprene is thicker and more durable than actual fabric, sewing neoprene may require special equipment. It it recommended that you use a more durable needle, use lubricant to help the needle pierce the neoprene, and work carefully with your machine. More details on all of that below.

If you plan on doing more than one or two tails, or plan on using thicker neoprene, you might be better off with an industrial-grade sewing machine.

Also, be aware of whether the neoprene you are using is coated or uncoated. Most neoprene is coated with a layer of nylon fabric. Not only is this better for using in tails than uncoated neoprene, its also better for sewing, as uncoated neoprene has too much friction to be passed through a sewing machine.

Details on sewing:

Heavy duty thread, like upholstery thread or other threads sold as “heavy duty” should be used for seam stability. A heavy duty needle should also be used. For singer machines, the shaft size is 100/16 (color code purple), for Kenmore 18/110 size (color code green), for Schmetz Microtex (color code purple). Using leather sewing needles have also been suggested. Be sure to have extra needles in case one breaks!

You will need to lubricate the needle, as neoprene is a rubber and will grab the needle making it very hard to sew and straining the machine. Do NOT use Vaseline or any petroleum based lubricant! Not on neoprene, not on latex! This will damage the neoprene making it irreparable. Even wetsuit manufacturers warn against it, saying it destroys the adhesive then penetrates the core making it impossible to repair. Use of Vaseline on a commercial wetsuit will actually void it's warranty.

Silicone based lube (diving grade) is recommended. However if there is silicone (any type of cure) on the neoprene do NOT use silicone based lube. It will break down the the silicone and melt. It can be used on plain neoprene or neoprene with latex. Water based lubricants (or "personal lubricants") can also work well, and are available at any pharmacy or grocery store.

Lube the needle, use the the suggested needle if possible, and go slowly. Due to the heavy thickness of the material, you may need to remove the presser foot to have enough room to sew it properly. Check the stitching every so often to make sure there are no issues, and stop if the machine starts making bad noises or you smell anything burning/burning rubber. Be aware that overheating may be an issue, so be sure to take breaks if needed.

Don't forget to mark the seam allowance desired on the sewing plate, so you can line it up with the fabric as you go. Your stitching lines will be much straighter that way. If you have not sewn before, I suggest practicing on any other scrap fabric to get the maneuvering down first. Otherwise you may be making very good friends with a seam ripper- and stretch seams are pain in the behind to take out! But know that if you DO mess up, seam ripping and starting over is an option.

Another option is to hand sew the neoprene. If you are sewing neoprene thicker than 2 or 2.5mm this may be the better option as opposed to machine sewing. Upholstery grade thread and upholstery needle is recommended. A blanket stitch/button hole stitch will work well. ( Spacing about 3/32-1/8”.

For adhering smaller areas of neoprene, or for patching rips/tears there are the following: Seal Cement Contact Cement for Neoprene ( and Aquaseal Urethane Repair Adhesive and Sealant (

Can I use spandex to make an ALEX tail?

It is possible, yes, but might not be recommended. There is one group that believes the ‘looser’ weave of spandex (as opposed to the solid rubber neoprene) gives too much skin contact with the ALEX to be safe. There is another that believes the looser weave means that over time, more water will pass through the ALEX and remove enough of the harmful chemicals to be safe. Use your own judgement. If you do use it, you need to use a slightly different construction technique and stretch the fabric on a frame while applying the ALEX and while painting, otherwise it will crack when stretched when you wear it.

Should I use spandex or neoprene for a fabric tail?

This is largely personal preference. Spandex is thinner, stretchier, easier to work with, and relatively inexpensive compared to the alternatives. Neoprene is thicker (a solid sheet of coated rubber, essentially) ,harder to work with, rough on sewing machines, and expensive, but some would argue gives a nicer-looking end product, is easier to paint, and does a (relatively) better job hiding the wearer’s legs and fin(s).

What is neoprin? Is that the same as neoprene?

Neoprin is a material that can be thought of as somewhere in between spandex and neoprene. It’s thin and stretchy, like spandex, but solid like neoprene. It’s also cheaper than neoprene, and can be worked with without any special techniques or precautions. Some prefer it for fabric tails, and it may be suitable for homemade latex tails.

Where can I buy neoprene to make a tail, and what kind should I buy?

The most popular places to buy neoprene are Macro International (pricing varies), Foam Order ($75.60 per 51" x 83" sheet), Seattle Fabrics ($4.50 per square foot), and Rockywoods Outdoor Fabrics ($12 per foot - 50'' in wide by the linear foot; or $50-$72 per full sheet).

The first thing you should know about neoprene is what it is, and what kinds you should look for! Neoprene is a family of synthetic rubbers that is used in a multitude of things for it's ability to stretch, protect, insulate, be abrasion-resistant, chemical-resistant, waterproof, and buoyant. It is the material that wet suits are made out of!

Neoprene thickness can range from 1.5mm to 6.5mm. You want to stay at or under 3mm. While some like the thicker 3mm material for more warmth and elasticity, most prefer the thinnest 1.5mm material. Most sewing machines can handle 1.5mm neoprene when certain steps are taken (see "Can I sew neoprene on my sewing machine?"). However 3mm or higher you may have to seek out an industrial strength sewing machine or hand stitch the material. Keep in mind that neoprene is buoyant, so the thicker the material is the more you will float. The most common thickness for making tails is the 1.5-2mm.

The type of neoprene you want to look for is fabric backed neoprene. The fabric backing allows you to put on and take off the neoprene with more ease. Also the fabrics come in a multitude of colors and give a surface that will take paint well. Make sure to get the fabric backing on both sides (one side will be the colored side). Smooth neoprene is very sticky when in contact with the skin, making it extremely hard to get on and off, and will not hold paint on it's surface. Therefore it is not recommended.

Neoprene is not only more durable, and gives other great swimmable qualities to one's tail (like insulation), but it also looks more realistic than a fabric tail! The material is thicker, so the appearance of legs and monofins through the tail is minimized!

Note that to save money on expensive material. You can alter the “basic tailmaking” process by cutting pieces out for the body of the tail, then cut the fluke pieces out separately and attach it later with a attractively shaped seam.

How much fabric do I need to make a tail?

This will depend on a number of factors including your height, size and type of fin used, and the extra length/width your aesthetic design of the fin requires. It also partially depends on the bolt width (or neoprene sheet size) of your chosen material and if you can fit the two halves of the tail pattern on one piece of fabric. You will have a better idea of how much fabric you need once you get your measurements and make the pattern with your design. If the material you are using is not too expensive you may wish to err on the side of caution. If the tail turns out too short you'll either have to make a new one or somehow extend the tail with separate pieces of fabric.

What kind of paint should I use to paint my tail?

People seem to prefer the Createx family of airbrush paints, which heat-cure to a relatively soft film and use automotive-grade pigments which do not degrade with prolonged light exposure. It is important to note that Createx paints MUST be cured with a heat gun. Createx paint comes in a variety of finishes for different effects.

Do I need an airbrush? What else can I use?

You don’t need an airbrush, but for best results it’s generally recommended.

Can I add glitter to the paint when airbrushing?

Yes, you can add special-purpose airbrushable metallics or glitter, but not general craft glitter which is too big to be airbrushed. Even with airbrushable additives, you must clean your airbrush and tips very thoroughly to avoid clogging.

Do I need a compressor for my airbrush?

You do not ‘need’ a compressor, but it helps. You can purchase cans of propellant and an adapter to work with your airbrush, but this is an extra expense that will add up, and is arguably less environmentally friendly (with the aerosol and cans). If this is something you want to get into as a hobby it might be worth investing in a compressor.

How do I make a molded latex or silicone tail?

Making a molded tail is a complex process and generally considered a very advanced skill that few casual crafters attempt. There are tutorials online for this sort of thing, but most people who make large molded costumes like this take classes in sculpting, mold making and, special effects costuming. If you do wish to pursue molding, you may wish to find a local workshop or class on the subject.

What silicone should I use to make a silicone tail?

Platinum cure or addition cure silicones are recommended. These are special effects products used for applications where there will be skin contact, like medical prosthetics or costumes. Brand names for these products include Dragon Skin and PlatSil Gel.

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