Guide to Synthetic Fude by vandalimism

All links are non-affiliated and are included for citing references.
I created this guide because I couldn’t find a comprehensive overview of synthetic fude (which refers to, in this context, artisanal makeup brushes)—a proper niche within a niche. Thus, I have compiled a list of makeup brush lines that are from OEMs (Original Equipment Manufacturers make products for other brands) and are 100% synthetic. The consensus is that synthetics are for liquids/creams, while animal hairs are for powders. Brush lines with natural and synthetic fibers typically reserve a pure or blended mix of synthetic fibers for lip, eyeliner, eyebrow, and liquid/cream face brushes. Consequently, drugstore synthetic brushes may be satisfactory for these use cases. However, the smoothness and stiffness of synthetic fibers result in poor performance with powder cosmetics and scratchiness on a sensitive face respectively. By exploring a selection of fude that use the latest synthetic fiber technology, I intend to guide readers seeking a better experience from their current synthetic brushes. In addition, I hope to see more fude enthusiasts create posts or videos dedicated to reviewing their synthetic fude collection since there’s a lack of such content on the internet.
Information from My Blush Betty, Jackson's Art, Kingyin, etc. is used as preliminary research on synthetic makeup brushes' history and current landscape. The lack of cuticles in synthetic fibers means that they don't retain as much powder but also bacteria as animal hair; the resiliency of synthetic fibers also means that they can withstand frequent washings, leading to a more hygienic makeup routine. The primary goals in development are better powder absorption by texturizing and crimping synthetic fiber and to be more eco-friendly by relying less on fossil fuels. The unstable supply of fur and customer ethical concerns has dramatically increased the demand for synthetic alternatives to natural hair.

Types of Synthetic Makeup Bristles

• Polystyrene
• Polyamide: Nylon (e.g. Tynex)
• Polyester: PBT (e.g. Taklon, BASF's fiber, Naturlon 60 🌽, etc.)
• Polyester: PTT (e.g Natrafil 🌽, Sorona 🌽, Tafre 🌽 🦠, etc.)
• Unknown: (MCF)

Japanese Synthetic Fude

Name	Number of Brushes	Bristle Material	Ferrule Material	Handle Material	Availability	Reviews*
Chikuhodo AF (2016)	9	PTT 🌽🦠	?	?	Beautylish, CDJapan, Fude Beauty 👥	qaganoficeandfire, enflame, donothingdilettante, un3xpectedfate, ---boop---, makeupmatters1, pressedorchids
Hakuhodo I (2020)	46	Nylon, PBT	Brass	Wood	Hakuhodo USA, Fude Japan 👤	jaybirdwalking, jaybirdwalking
Hakuhodo i (2020)	19	?	Aluminum	Plastic	Hakuhodo USA 👤	jaybirdwalking, twindly, un3xpectedfate
Koyudo Makiko (2020)	5	?	?	Wood	CDJapan, Fude Beauty 👥	kinkysweat, krutikapuntambekar, xleucax, pressedorchids
Nakamura Seisakusho Moe (2020)	7	PBT 📏🦠	?	?	Fude Beauty 👤	kinkysweat
Nakamura Seisakusho Ai (2020)	8	PBT 📏	?	?	Fude Beauty 👤	kinkysweat, pressedorchids
Koyudo La Fuga del Gatto (2021)	6	PBT & PTT 🌽📏	Brass	?	Beautylish, CDJapan, Fude Beauty 👥	kinkysweat
Uyeda Bisyodo Futur (2021)	13	PBT	?	Wood	Fude Beauty, Fude Japan 👤	kinkysweat, tortorre, irulancorrino, NYanae555
Uyeda Bisyodo Shiori (2021)	14	? 🦠	Brass	Wood	CDJapan, Fude Beauty, Fude Japan 👥	tpmmpt11, 0410maria1995
Chikuhodo Framboise (2021)	5	PBT	?	?	Beautylish, CDJapan, Fude Beauty, Fude Japan 🫂	?

Chinese Synthetic Fude

Name	Number of Brushes	Availability	Reviews*
Shou Shou Lang Velvet 🌽	11	AliExpress 🫂	?
Shou Shou Lang Pink 🌽	11	AliExpress 🫂	?
Shou Shou Lang Yellow 🌽	11	AliExpress 🫂	?
Shou Shou Lang White	13	AliExpress 🫂	?
Shou Shou Lang Blue	9	AliExpress 🫂	?
Qin Zhi Navy / White Short Handle	3 / 4	AliExpress 👥 / AliExpress 👤	?
Qin Zhi Blue / Purple	6 / 7	AliExpress 🫂 / AliExpress 🫂	?
Qin Zhi Black	5	AliExpress 🫂	?
Qin Zhi Red	8	AliExpress 🫂	xleucax
Qin Zhi Brown	9	AliExpress 🫂	?

*Additional reviews can be found on product pages from online retailers.
Key

🌽 = advertises using more eco-friendly fibers
📏 = advertises using thin (0.05-0.07mm) fibers which result in a softer brush
🦠 = advertises adding an anti-microbial agent e.g. silver in fibers
👤 = is available only as individual brushes
👥 = is available as individual brushes and as a set/s
🫂 = is available only as a set/s

There are many unknown variables in the table due to trade secrets, language barriers, the relative niche of synthetic fude, and my lack of physical samples. In addition, the availability sections were written from an American perspective, which might have excluded some international options.

Review of Uyeda Bisyodo Shiori Eye Brushes (CDJapan)

It took 11 business days for me to receive my brushes (purchased with my own money) from CDJapan. The website was easy to navigate, but there was no option to filter for all makeup brushes in a synthetic material. I used an approximately $3 off coupon, and the threshold for free shipping was around $90. Fude Beauty and Fude Japan also carried the Uyeda Bisyodo Shiori series; however, their minimums for free shipping were too high i.e. at least $300 for my budget. Beautylish did not have the brand in its inventory. I also attempted to make an account for CDJapan but never received an email verification in my inbox or spam folder. So, I had to use the guest checkout and forwent points that I could have used in a future purchase for a discount. I still received shipping and invoice emails, so I knew I didn't mistype my email address. If I felt strongly about the points, I would've contacted their customer service but honestly didn't mind. The brushes also came with CDJapan's 1-year warranty on makeup brushes, which signaled confidence in quality.
Description of UB Shiori Brushes

Name	Shape	General Use
S-504	Large Angled	Contour eye and nose
S-505	Pencil	Precisely apply eyeshadow on the inner corner, uppelower lashlines, etc.
S-507 (the bigger version of S-508)	Large Shader	Quickly apply a wash of eyeshadow all over the eyelid
S-508 (the smaller version of S-507)	Small Shader	Apply eyeshadow below the eyelid crease, deepen the outer thirds, etc.
S-509	Smudge	Apply eyeshadow as diffused eyeliner from the inner corner to the wing

​
Visual Comparison of UB Shiori Brushes to Similar Brushes
Comparison of UB Shiori Brushes to RT Brushes

UB's Characteristic	Result	Comments
More precisely bundled	More precise application of eyeshadow, which is helpful near the lashlines	The quality control from being hand-made by skilled artisans sets synthetic fude apart from drugstore options and is the primary reason for the cost. There are fewer stray hairs to accidentally poke the eye.
Denser	Absorb more powder, which means fewer re-applications of pigment to get desired opacities	People with difficulty getting colors to show on their skin tone may find that denser brushes can apply eyeshadow in a much more reasonable time.
More flexible fibers	Less "pokey" experience i.e. less pushback when using more pressure, which means less irritation for sensitive skin	The use of flexible fibers is apparent in shorter bristles. For example, I find the longer-haired RT 402 to be soft but any of the RT eye brushes to be pokey. I need to be mindful of holding RT eye brushes at certain angles and pressure to use them on my eyelids. To offset the stiffness of synthetic fibers, drugstore brushes are sometimes bundled in a tapered shape e.g. RT 402 so that as many of the finer-tipped ends can contact the face; but this can also limit the brush shapes that give a soft experience.
Brass ferrule	Brass is less prone to rust than aluminum, which may result in longer brush life	My decade-old aluminum-ferruled RT brushes haven't developed rust anyway. Brass feels more hefty and luxurious than aluminum.

After testing on my eyelids and fingertips, these are the softest brushes that I've ever used. Even with pressure, UB brushes don't feel as rough and exfoliating as RT brushes i.e. there is less audible "bristle" noise during use. Despite being denser than the RT brushes, UB brushes still feel softer due to having more flexible bristles. In comparison to my natural-haired BB Eyeshadow brush, UB brushes feel slightly slicker (but still much less slick than RT brushes). BB's and UB's fiber densities and flex feel similar.
My assessment of these brushes may be hindered by my relatively small collection of brushes. As a result, I can only compare expensive synthetic fude to mostly drugstore synthetic brushes. In addition, my RT and BB brushes are more than a decade old, and I have used my UB brushes for only two months (at the time of writing). I don't intend to purchase natural hair brushes, so I won't be able to compare natural hair to synthetic fude in the future.
I will also update the guide as I collect more synthetic fude and if readers suggest any corrections or give additional information. Feel free to discuss your experiences, good or bad, with synthetic fude in the replies!

Guide to Synthetic Fude by vandalimism

All links are non-affiliated and are included for citing references.
I created this guide because I couldn’t find a comprehensive overview of synthetic fude (which refers to, in this context, artisanal makeup brushes)—a proper niche within a niche. Thus, I have compiled a list of makeup brush lines that are from OEMs (Original Equipment Manufacturers make products for other brands) and are 100% synthetic. The consensus is that synthetics are for liquids/creams, while animal hairs are for powders. Brush lines with natural and synthetic fibers typically reserve a pure or blended mix of synthetic fibers for lip, eyeliner, eyebrow, and liquid/cream face brushes. Consequently, drugstore synthetic brushes may be satisfactory for these use cases. However, the smoothness and stiffness of synthetic fibers result in poor performance with powder cosmetics and scratchiness on a sensitive face respectively. By exploring a selection of fude that use the latest synthetic fiber technology, I intend to guide readers seeking a better experience from their current synthetic brushes. In addition, I hope to see more fude enthusiasts create posts or videos dedicated to reviewing their synthetic fude collection since there’s a lack of such content on the internet.
Information from My Blush Betty, Jackson's Art, Kingyin, etc. is used as preliminary research on synthetic makeup brushes' history and current landscape. The lack of cuticles in synthetic fibers means that they don't retain as much powder but also bacteria as animal hair; the resiliency of synthetic fibers also means that they can withstand frequent washings, leading to a more hygienic makeup routine. The primary goals in development are better powder absorption by texturizing and crimping synthetic fiber and to be more eco-friendly by relying less on fossil fuels. The unstable supply of fur and customer ethical concerns has dramatically increased the demand for synthetic alternatives to natural hair.

Types of Synthetic Makeup Bristles

• Polystyrene
• Polyamide: Nylon (e.g. Tynex)
• Polyester: PBT (e.g. Taklon, BASF's fiber, Naturlon 60 🌽, etc.)
• Polyester: PTT (e.g Natrafil 🌽, Sorona 🌽, Tafre 🌽 🦠, etc.)
• Unknown: (MCF)

Japanese Synthetic Fude

Name	Number of Brushes	Bristle Material	Ferrule Material	Handle Material	Availability	Reviews*
Chikuhodo AF (2016)	9	PTT 🌽🦠	?	?	Beautylish, CDJapan, Fude Beauty 👥	qaganoficeandfire, enflame, donothingdilettante, un3xpectedfate, ---boop---, makeupmatters1, pressedorchids
Hakuhodo I (2020)	46	Nylon, PBT	Brass	Wood	Hakuhodo USA, Fude Japan 👤	jaybirdwalking, jaybirdwalking
Hakuhodo i (2020)	19	?	Aluminum	Plastic	Hakuhodo USA 👤	jaybirdwalking, twindly, un3xpectedfate
Koyudo Makiko (2020)	5	?	?	Wood	CDJapan, Fude Beauty 👥	kinkysweat, krutikapuntambekar, xleucax, pressedorchids
Nakamura Seisakusho Moe (2020)	7	PBT 📏🦠	?	?	Fude Beauty👤	kinkysweat
Nakamura Seisakusho Ai (2020)	8	PBT 📏	?	?	Fude Beauty👤	kinkysweat, pressedorchids
Koyudo La Fuga del Gatto (2021)	6	PBT & PTT 🌽📏	Brass	?	Beautylish, CDJapan, Fude Beauty 👥	kinkysweat
Uyeda Bisyodo Futur (2021)	13	PBT	?	Wood	Fude Beauty, Fude Japan 👤	kinkysweat, tortorre, irulancorrino, NYanae555
Uyeda Bisyodo Shiori (2021)	14	? 🦠	Brass	Wood	CDJapan, Fude Beauty, Fude Japan 👥	tpmmpt11, 0410maria1995
Chikuhodo Framboise (2021)	5	PBT	?	?	Beautylish, CDJapan, Fude Beauty, Fude Japan🫂	?

Chinese Synthetic Fude

Name	Number of Brushes	Availability	Reviews*
Shou Shou Lang Velvet 🌽	11	AliExpress 🫂	?
Shou Shou Lang Pink 🌽	11	AliExpress 🫂	?
Shou Shou Lang Yellow 🌽	11	AliExpress 🫂	?
Shou Shou Lang White	13	AliExpress 🫂	?
Shou Shou Lang Blue	9	AliExpress 🫂	?
Qin Zhi Navy / White Short Handle	3 / 4	AliExpress 👥 / AliExpress 👤	?
Qin Zhi Blue / Purple	6 / 7	AliExpress 🫂 / AliExpress 🫂	?
Qin Zhi Black	5	AliExpress 🫂	?
Qin Zhi Red	8	AliExpress 🫂	xleucax
Qin Zhi Brown	9	AliExpress 🫂	?

*Additional reviews can be found on product pages from online retailers.
Key

🌽 = advertises using more eco-friendly fibers
📏 = advertises using thin (0.05-0.07mm) fibers which result in a softer brush
🦠 = advertises adding an anti-microbial agent e.g. silver in fibers
👤 = is available only as individual brushes
👥 = is available as individual brushes and as a set/s
🫂 = is available only as a set/s

There are many unknown variables in the table due to trade secrets, language barriers, the relative niche of synthetic fude, and my lack of physical samples. In addition, the availability sections were written from an American perspective, which might have excluded some international options.

Review of Uyeda Bisyodo Shiori Eye Brushes (CDJapan)

It took 11 business days for me to receive my brushes (purchased with my own money) from CDJapan. The website was easy to navigate, but there was no option to filter for all makeup brushes in a synthetic material. I used an approximately $3 off coupon, and the threshold for free shipping was around $90. Fude Beauty and Fude Japan also carried the Uyeda Bisyodo Shiori series; however, their minimums for free shipping were too high i.e. at least $300 for my budget. Beautylish did not have the brand in its inventory. I also attempted to make an account for CDJapan but never received an email verification in my inbox or spam folder. So, I had to use the guest checkout and forwent points that I could have used in a future purchase for a discount. I still received shipping and invoice emails, so I knew I didn't mistype my email address. If I felt strongly about the points, I would've contacted their customer service but honestly didn't mind. The brushes also came with CDJapan's 1-year warranty on makeup brushes, which signaled confidence in quality.
Description of UB Shiori Brushes

Name	Shape	General Use
S-504	Large Angled	Contour eye and nose
S-505	Pencil	Precisely apply eyeshadow on the inner corner, uppelower lashlines, etc.
S-507 (the bigger version of S-508)	Large Shader	Quickly apply a wash of eyeshadow all over the eyelid
S-508 (the smaller version of S-507)	Small Shader	Apply eyeshadow below the eyelid crease, deepen the outer thirds, etc.
S-509	Smudge	Apply eyeshadow as diffused eyeliner from the inner corner to the wing

​
Visual Comparison of UB Shiori Brushes to Similar Brushes
Comparison of UB Shiori Brushes to RT Brushes

UB's Characteristic	Result	Comments
More precisely bundled	More precise application of eyeshadow, which is helpful near the lashlines	The quality control from being hand-made by skilled artisans sets synthetic fude apart from drugstore options and is the primary reason for the cost. There are fewer stray hairs to accidentally poke the eye.
Denser	Absorb more powder, which means fewer re-applications of pigment to get desired opacities	People with difficulty getting colors to show on their skin tone may find that denser brushes can apply eyeshadow in a much more reasonable time.
More flexible fibers	Less "pokey" experience i.e. less pushback when using more pressure, which means less irritation for sensitive skin	The use of flexible fibers is apparent in shorter bristles. For example, I find the longer-haired RT 402 to be soft but any of the RT eye brushes to be pokey. I need to be mindful of holding RT eye brushes at certain angles and pressure to use them on my eyelids. To offset the stiffness of synthetic fibers, drugstore brushes are sometimes bundled in a tapered shape e.g. RT 402 so that as many of the finer-tipped ends can contact the face; but this can also limit the brush shapes that give a soft experience.
Brass ferrule	Brass is less prone to rust than aluminum, which may result in longer brush life	My decade-old aluminum-ferruled RT brushes haven't developed rust anyway. Brass feels more hefty and luxurious than aluminum.

After testing on my eyelids and fingertips, these are the softest brushes that I've ever used. Even with pressure, UB brushes don't feel as rough and exfoliating as RT brushes i.e. there is less audible "bristle" noise during use. Despite being denser than the RT brushes, UB brushes still feel softer due to having more flexible bristles. In comparison to my natural-haired BB Eyeshadow brush, UB brushes feel slightly slicker (but still much less slick than RT brushes). BB's and UB's fiber densities and flex feel similar.
My assessment of these brushes may be hindered by my relatively small collection of brushes. As a result, I can only compare expensive synthetic fude to mostly drugstore synthetic brushes. In addition, my RT and BB brushes are more than a decade old, and I have used my UB brushes for only two months (at the time of writing). I don't intend to purchase natural hair brushes, so I won't be able to compare natural hair to synthetic fude in the future.
I will also update the guide as I collect more synthetic fude and if readers suggest any corrections or give additional information. Feel free to discuss your experiences, good or bad, with synthetic fude in the replies!

Guide to Synthetic Fude by vandalimism

All links are non-affiliated and are included for citing references.
I created this guide because I couldn’t find a comprehensive overview of synthetic fude (which refers to, in this context, artisanal makeup brushes)—a proper niche within a niche. Thus, I have compiled a list of makeup brush lines that are from OEMs (Original Equipment Manufacturers make products for other brands) and are 100% synthetic. The consensus is that synthetics are for liquids/creams, while animal hairs are for powders. Brush lines with natural and synthetic fibers typically reserve a pure or blended mix of synthetic fibers for lip, eyeliner, eyebrow, and liquid/cream face brushes. Consequently, drugstore synthetic brushes may be satisfactory for these use cases. However, the smoothness and stiffness of synthetic fibers result in poor performance with powder cosmetics and scratchiness on a sensitive face respectively. By exploring a selection of fude that use the latest synthetic fiber technology, I intend to guide readers seeking a better experience from their current synthetic brushes. In addition, I hope to see more fude enthusiasts create posts or videos dedicated to reviewing their synthetic fude collection since there’s a lack of such content on the internet.
Information from My Blush Betty, Jackson's Art, Kingyin, etc. is used as preliminary research on synthetic makeup brushes' history and current landscape. The lack of cuticles in synthetic fibers means that they don't retain as much powder but also bacteria as animal hair; the resiliency of synthetic fibers also means that they can withstand frequent washings, leading to a more hygienic makeup routine. The primary goals in development are better powder absorption by texturizing and crimping synthetic fiber and to be more eco-friendly by relying less on fossil fuels. The unstable supply of fur and customer ethical concerns has dramatically increased the demand for synthetic alternatives to natural hair.

Types of Synthetic Makeup Bristles

• Polystyrene
• Polyamide: Nylon (e.g. Tynex)
• Polyester: PBT (e.g. Taklon, BASF's fiber, Naturlon 60 🌽, etc.)
• Polyester: PTT (e.g Natrafil 🌽, Sorona 🌽, Tafre 🌽 🦠, etc.)
• Unknown: (MCF)

Japanese Synthetic Fude

Name	Number of Brushes	Bristle Material	Ferrule Material	Handle Material	Availability	Reviews*
Chikuhodo AF (2016)	9	PTT 🌽🦠	?	?	Beautylish, CDJapan, Fude Beauty 👥	qaganoficeandfire, enflame, donothingdilettante, un3xpectedfate, ---boop---, makeupmatters1, pressedorchids
Hakuhodo I (2020)	46	Nylon, PBT	Brass	Wood	Hakuhodo USA, Fude Japan 👤	jaybirdwalking, jaybirdwalking
Hakuhodo i (2020)	19	?	Aluminum	Plastic	Hakuhodo USA 👤	jaybirdwalking, twindly, un3xpectedfate
Koyudo Makiko (2020)	5	?	?	Wood	CDJapan, Fude Beauty 👥	kinkysweat, krutikapuntambekar, xleucax, pressedorchids
Nakamura Seisakusho Moe (2020)	7	PBT 📏🦠	?	?	Fude Beauty 👤	kinkysweat
Nakamura Seisakusho Ai (2020)	8	PBT 📏	?	?	Fude Beauty 👤	kinkysweat, pressedorchids
Koyudo La Fuga del Gatto (2021)	6	PBT & PTT 🌽📏	Brass	?	Beautylish, CDJapan, Fude Beauty 👥	kinkysweat
Uyeda Bisyodo Futur (2021)	13	PBT	?	Wood	Fude Beauty, Fude Japan 👤	kinkysweat, tortorre, irulancorrino, NYanae555
Uyeda Bisyodo Shiori (2021)	14	? 🦠	Brass	Wood	CDJapan, Fude Beauty, Fude Japan 👥	tpmmpt11, 0410maria1995
Chikuhodo Framboise (2021)	5	PBT	?	?	Beautylish, CDJapan, Fude Beauty, Fude Japan 🫂	?

Chinese Synthetic Fude

Name	Number of Brushes	Availability	Reviews*
Shou Shou Lang Velvet 🌽	11	AliExpress 🫂	?
Shou Shou Lang Pink 🌽	11	AliExpress 🫂	?
Shou Shou Lang Yellow 🌽	11	AliExpress 🫂	?
Shou Shou Lang White	13	AliExpress 🫂	?
Shou Shou Lang Blue	9	AliExpress 🫂	?
Qin Zhi Navy / White Short Handle	3 / 4	AliExpress 👥 / AliExpress 👤	?
Qin Zhi Blue / Purple	6 / 7	AliExpress 🫂 / AliExpress 🫂	?
Qin Zhi Black	5	AliExpress 🫂	?
Qin Zhi Red	8	AliExpress 🫂	xleucax
Qin Zhi Brown	9	AliExpress 🫂	?

*Additional reviews can be found on product pages from online retailers.
Key

🌽 = advertises using more eco-friendly fibers
📏 = advertises using thin (0.05-0.07mm) fibers which result in a softer brush
🦠 = advertises adding an anti-microbial agent e.g. silver in fibers
👤 = is available only as individual brushes
👥 = is available as individual brushes and as a set/s
🫂 = is available only as a set/s

There are many unknown variables in the table due to trade secrets, language barriers, the relative niche of synthetic fude, and my lack of physical samples. In addition, the availability sections were written from an American perspective, which might have excluded some international options.

Review of Uyeda Bisyodo Shiori Eye Brushes (CDJapan)

It took 11 business days for me to receive my brushes (purchased with my own money) from CDJapan. The website was easy to navigate, but there was no option to filter for all makeup brushes in a synthetic material. I used an approximately $3 off coupon, and the threshold for free shipping was around $90. Fude Beauty and Fude Japan also carried the Uyeda Bisyodo Shiori series; however, their minimums for free shipping were too high i.e. at least $300 for my budget. Beautylish did not have the brand in its inventory. I also attempted to make an account for CDJapan but never received an email verification in my inbox or spam folder. So, I had to use the guest checkout and forwent points that I could have used in a future purchase for a discount. I still received shipping and invoice emails, so I knew I didn't mistype my email address. If I felt strongly about the points, I would've contacted their customer service but honestly didn't mind. The brushes also came with CDJapan's 1-year warranty on makeup brushes, which signaled confidence in quality.
Description of UB Shiori Brushes

Name	Shape	General Use
S-504	Large Angled	Contour eye and nose
S-505	Pencil	Precisely apply eyeshadow on the inner corner, uppelower lashlines, etc.
S-507 (the bigger version of S-508)	Large Shader	Quickly apply a wash of eyeshadow all over the eyelid
S-508 (the smaller version of S-507)	Small Shader	Apply eyeshadow below the eyelid crease, deepen the outer thirds, etc.
S-509	Smudge	Apply eyeshadow as diffused eyeliner from the inner corner to the wing

Visual Comparison of UB Shiori Brushes to Similar Brushes
Comparison of UB Shiori Brushes to RT Brushes

UB's Characteristic	Result	Comments
More precisely bundled	More precise application of eyeshadow, which is helpful near the lashlines	The quality control from being hand-made by skilled artisans sets synthetic fude apart from drugstore options and is the primary reason for the cost. There are fewer stray hairs to accidentally poke the eye.
Denser	Absorb more powder, which means fewer re-applications of pigment to get desired opacities	People with difficulty getting colors to show on their skin tone may find that denser brushes can apply eyeshadow in a much more reasonable time.
More flexible fibers	Less "pokey" experience i.e. less pushback when using more pressure, which means less irritation for sensitive skin	The use of flexible fibers is apparent in shorter bristles. For example, I find the longer-haired RT 402 to be soft but any of the RT eye brushes to be pokey. I need to be mindful of holding RT eye brushes at certain angles and pressure to use them on my eyelids. To offset the stiffness of synthetic fibers, drugstore brushes are sometimes bundled in a tapered shape e.g. RT 402 so that as many of the finer-tipped ends can contact the face; but this can also limit the brush shapes that give a soft experience.
Brass ferrule	Brass is less prone to rust than aluminum, which may result in longer brush life	My decade-old aluminum-ferruled RT brushes haven't developed rust anyway. Brass feels more hefty and luxurious than aluminum.

After testing on my eyelids and fingertips, these are the softest brushes that I've ever used. Even with pressure, UB brushes don't feel as rough and exfoliating as RT brushes i.e. there is less audible "bristle" noise during use. Despite being denser than the RT brushes, UB brushes still feel softer due to having more flexible bristles. In comparison to my natural-haired BB Eyeshadow brush, UB brushes feel slightly slicker (but still much less slick than RT brushes). BB's and UB's fiber densities and flex feel similar.
My assessment of these brushes may be hindered by my relatively small collection of brushes. As a result, I can only compare expensive synthetic fude to mostly drugstore synthetic brushes. In addition, my RT and BB brushes are more than a decade old, and I have used my UB brushes for only two months (at the time of writing). I don't intend to purchase natural hair brushes, so I won't be able to compare natural hair to synthetic fude in the future.
I will also update the guide as I collect more synthetic fude and if readers suggest any corrections or give additional information. Feel free to discuss your experiences, good or bad, with synthetic fude in the replies!