Types of waterproof sprays and how to use them

Points to consider when choosing the best spray for leather products and how to use it effectively

Waterproof spray complete Protects leather, fabric and outdoor gear

To make your precious leather products last longer,Waterproof sprayIt is essential to use. However, not all waterproof sprays are suitable for leather products, and some types of sprays can damage the leather. In this article, we will explain the types of waterproof sprays, scientific differences, and key points to use from a professional perspective, and explain how to choose the best waterproof spray for leather products.

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Introduction: What you can get from this article

This article is about waterproof spray Types, Chemistry, Environmental Regulations, Maintenance by Materials, Troubleshooting, Future Outlook This is the definitive guide that will allow you to learn all at once.
As I read on Genuine leather bag or Canvas bag We will also introduce actual product pages everywhere, so if you are interested, please tap to see them.

1. History of waterproofing and market size

1‑1. From oiled cloth to modern nanocoat

The origin of waterproofing was when 19th century fishermen soaked linseed oil into canvas. Since then, technology has evolved from paraffin, silicon, fluoropolymers, and nanoceramics.

1‑2. Trends in the size of domestic market

According to the latest report from Yano Economic Research Institute (published in March 2024), the market size for waterproof sprays alone is as follows.

year Market size Compared to previous year
2022 (Results) 11.3 billion yen ––
2023 (preliminary estimate) 11.8 billion yen +4.4 %
2024 (Predictions) 12.3 billion yen +4.2 %
2022 2023 2024* * Market size (billion yen) 123 118 113
Figure 2: Trends in the market size of waterproof spray (Yano Economic Research Institute 2024)

The growth is driven by outdoor demand and fashion applications, particularly Leather backpack The increase in purchasing is noticeable.

2. Basic Science: Molecular Mechanisms of Water Repellent and Waterproofing

2‑1. Contact and rolling angles

θ Material surface Water Droplets
Figure 1: The larger the contact angle θ, the higher the water repellency.

Hydrophobic when the contact angle θ is 90° or higher, and superhydrophobic when the contact angle θ is 150° or higher. If the rolling angle α is below 10°, it is considered to be practical water repellent.

2‑2. Cassie–Baxter and Wenzel

The microstructure holds the air layer, which floats water droplets, enhancing water repellency. Even on rough surfaces, contact angle decreases when water infiltrates.

2‑3. Silicon film vs. Fluorine film

Silicon is flexible and thick film, while fluorine is thin film, and oil repellent is highly oil repellent.Crazy Horse Leather Highly transparent nano SiO₂ goes well with oil-rich leather like this.

3. Comparison of 8 commercially available types

Si F PF Nano HC H₂O Wax Oil
type Strong Points Cons Recommended materials
silicon Waterproof and low price Reduced breathability Canvas/tent
Fluorine (C6) Oil-repellent ◎ Thin film Environmental regulations challenges Smooth leather
PFAS Free Environmental consideration Durability △ PU leather
Nano SiO₂ Longest durability expensive Luxury leather
Hydrocarbons Penetration ◎ Burnable Oil leather
Water-based PU Low odor Short effect Synthetic leather
Beeswax Natural and glossy Frequently reapplied Work boots
Vegetable oil Mold-proof Water repellent suede

4. PFAS and Environmental Regulations

The EU submitted a proposal to ban PFAS entirely in 2023. Japan has also set the groundwater standard of 1 µg/L.Business bag There is a growing trend to choose PFAS-free products for everyday use.

5. Material compatibility matrix

Each material is recommended and deprecated as follows:

material Recommended Deprecated
Crazy Horse Nano SiO₂ Thick film silicon
smooth Fluorine C6 Beeswax
PU Water-based PU Solvent Fluorine
Sail silicon Thick beeswax coating
suede Vegetable oil Hydrocarbons

6. How to choose a scene

6‑1. Commuting

Thin film fluorine is the best option to avoid color transfer to suits.

6‑2. Travel

Large travel bag Since there is a lot of wear, we recommend using two layers of nano-based + silicon as a priority.

6‑3. Outdoor

Canvas gear, which has the risk of a bonfire fire, can be used with silicone gear.

7. Construction procedure

1 2 3 4 5 Brushing masking uniform spray 15 minutes dry 12 h Dry
Figure 3: Waterproof spray installation 5 steps overview
  1. Brushing → Neutral cleaner.
  2. Masking (metal fittings).
  3. Reciprocating spray at a distance of 25 cm.
  4. Dry for 15 minutes and apply twice.
  5. Naturally dry for more than 12 hours.

8. Maintenance by material

Each material differs in terms of "points that are prone to getting dirty" and "appropriate care products." The table below summarizes the recommended steps for the 15 representative materials. When you're confusedCleaner → Leather-retaining/flexible → WaterproofPlease use the three steps as a reference.

material Major risks Recommended cleaner Leather/Fabricing agent Waterproof spray Re-construction estimate
Full grain leather Dry cracks and discoloration Weak alkaline soap + horse hair brush Lanolin 5% Cream Fluorine C6 or Nano SiO₂ 4-6 weeks
Top grain leather Surface scratches Neutral foam cleaner Emulsified wax Fluorine C6 6-8 weeks
Vegetarian (Numae) Water stains and sunburn Mink Oil Soap Beeswax balm Nano SiO₂ 2-4 weeks
Chrome tanned leather Silver face Alcohol-free cleaner Ceramide cream Fluorine C6 6 weeks
Oiled leather Oil transfer Liquid Glycerin Neats Foot Oil Hydrocarbons 8 weeks
suede Mud stains and uneven color Brushed Rubber + Suede Shampoo Water-repellent protective spray (oil-free) Vegetable oil type 2 weeks
Nubuck Shiny Sandwich Lacer No leather retainer required PFAS-free water-based 3 weeks
Cordban Swelling Deer leather cloth wipe Serum cream Nano SiO₂ 8 weeks
Patent leather Cloudy fingerprints Silicon cloth No need No need to waterproof (resin coat) ―
Canvas (cotton) Mud stains and mold Weak acidic detergent 30℃ Hand wash Water-repellent wax (light coating) Silicon system 4 weeks
Ballistic nylon Oil stain Neutral detergent 40℃ No fabric softener required Fluorine C6 12 weeks
Cordura nylon Fluffy Laundry net/weak water flow No need Fluorine C6 10 weeks
Polyester (ripstop) UV degradation Low temperature washing UV Guard Spray PFAS Free 10 weeks
PU leather Hydrolysis and sticky Non-alcoholic wet Silicone Protective Water-based PU 6 weeks
PVC/TPU Hardened/Curified Wipe with weak alcohol Plasticizer Coat No need to waterproof ―

8‑1. Leather: Common routine

  1. Dry wipe ... Just removing dust reduces the water stain incidence rate by more than 30%.
  2. cleaning ...Whisk the special soap at pH 7 and gently create a circle.
  3. Leather maintenance ...Oil/wax isMultiple thin coatsis the golden rule. Thick coating is a hotbed for mold.
  4. waterproof ... 25cm Distance and round trips are basically two times. Hair dryers are strictly prohibited immediately after.
  5. storage ...Ventilation: 15-25°C, humidity: 50% or less. Regularly replace the silica gel.

8‑2. Fabrics and synthetic fibers: Common routine

  1. Mud stains ... Brush after drying → Soak and wash to prevent color transfer.
  2. Washing temperature ...The upper limit is 40°C for nylon and 30°C for polyester. High temperatures cause the water-repellent layer to be separated.
  3. dehydration ...Towel drying is recommended. Centrifugal dehydration leads to stretching of the fabric.
  4. Thermal processing ... Cannot iron (Teflon melt). Wrinkles are 30 cm away from steam.
  5. Waterproof reprocessed ...Spray after drying completely. Spraying while wet will turn white.

8‑3. Failure Rescue Hayami

  • Whitening (Leather) ... 40℃ Warm air → Emulsifying cream.
  • Oil stain (cloth) ...Site neutral dishwashing detergent → Wash at 30°C.
  • Mold (common) ...Spray 70% ethanol and dry in the shade for 30 minutes.
  • Sticky (PU) ... Low concentration IPA wipe → Apply silicone protective agent.

9. Failure and recovery

The waterproof spray isSpray distance, temperature and humidity, compatibility with materialsIf you make a mistake, it will lead to unexpected problems. We have organized the causes and recovery flows by symptoms.

Symptoms Main causes first aid Fundamental measures
Whitening (powdering) Installation/solvent suddenly becomes vaporized at humidity of over 80% 40℃ Warm air 3 min → Wipe dry Reinstallation with humidity below 60%
Thin film twice is iron rules
Unevenness and spots Close-range spray/Spraying the can too much and turning it into a droplet Fully remove with neutral cleaner 25 cm away zigzag spray
Movement speed 20 cm/s approximate
Dark stains Thick silicone coating on suede Brushed Eraser → Sandpaper #600 Change to vegetable oil or PFAS free
Sticky Solvent-based PU leather IPA 30% Wipe → Silicone Protective Film Switch to water-based PU spray
Stinks Solvent vapor residue/Hydrosive mold Newspaper + baking soda sealed 24 h Breathing 48 h → Lightly applied again
Color transfer Uncured film transferred to clothing Clothes are washed at 40°C
The bag is a neutral cleaner		 24 hours of curing time
Water repellent reduction Wearing 10,000 times or UV degradation Re-spray (two layers) Uses wear-resistant type or nano SiO₂
Silver face crack Use alkaline detergent → pH shock Moisturize with ceramide cream Improved to weakly acidic cleaners

9‑1. Recovery Flowchart

  1. Symptom identification ...Records the surface temperature and humidity, whether it is spotted or powdered.
  2. cleaning ...A versatile neutral soap with a pH of 7 ±0.5 is versatile. Suede is diluted with water 1:1.
  3. Drying evaluation ...Reinstallation is possible if the weight change is below 1%.
  4. Reconstruction ...Patch test with a different material before using the original spray.
  5. protection ... The finishing touch is made with a leather-retaining cream or UV protector for 1.5 times the durability.

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10. Verify misconceptions

I often hear about it on social media and in stores10 common beliefsWe will verify this based on academic data and international standards.

# Common misconceptions Verification results Fundamentals and sources
1 "Waterproof = completely waterproof, so it's fine to submerge" × Contact angle ≠ Water pressure resistant. Infiltrates between the fibers. ISO 4920 vs ISO 811 Water resistance comparison test
2 "The thicker the coat, the longer the last" × Film thickness exceeding 1 µm crack increase rate +60% JIS K 6404 Taber wear 500 g x 1,000 rev
3 "Leather can't breathe" △ The oxygen permeability is approximately -20% ASTM D1434 Gas Permeability Test
4 "It penetrates well when applied in the rain." × The water film interferes with the interface and causes whitening In-house 2024 Experimental data n=20
5 "PFAS will be banned all at once soon." △ 2030 The gradual reduction plan for 2030 is not an immediate ban. ECHA 2023 Restrictions p.35
6 "Water-repellent can prevent 100% dirt." × Friction contamination cannot be prevented ISO 22196 Adhesion Test
7 "Waterproof spray = anti-mold effect" × Anti-mold ingredients must be added separately Ministry of Health, Labor and Welfare Standards for External Non-Pharmaceutical Products
8 "Silicon blocks leather, but fluorine is safe." △ Both have the same molecular size and different film thickness. Nature Mater. 2022
9 "A candle is applied and spray is not required." △ Fabric is possible, leather is risky of oil burning Tokyo Leather Technology Center Survey 2021
10 "Washing water will result in zero waterproofing." × Nano SiO₂ has a contact angle of 130° after washing five times MIT 2022 Graphene Composite Film Paper

10‑1. The background of misunderstanding

Many misconceptionsContact angle (apparently water-repellent) and water-resistant pressure (actual waterproofing)This is caused by confusion and exaggeration of old C8 fluoride regulations information. Correct evaluation indicators are divided into different uses, such as the "JIS L 1092 Low Water Pressure Method" and the "ISO 4920 Spray Method."

10‑2. Correct decision frame

  1. The purpose Water repellent / waterproof / Anti-fouling / Oil resistant Disassembled into
  2. Check the physical properties of materials (roughness, water absorption, heat resistance)
  3. Comparing the standard values ​​(contact angle, water pressure, number of wear)
  4. First material is patch test (5 x 5 cm)

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11. Future technology

Waterproof and water repellent technologyEnvironmental regulations and high functionalityIt is rapidly evolving into both wheels. A look at the key ideas along with TRL (Technology Readiness Level).

Technology concept principle merit assignment TRL Commercial forecast
Self-degradation type PFAS‑free Fluorine Polymer Hydrolysis Trigger Chain Dissociation Decomposed when disposed of Durability reduced by 30% 5‑6 2028
Graphene‑SiO₂ Composite Super Water Repellent π bond + nanoprojection structure Wear: Hold 30,000 times High cost 4‑5 2030
Zwitterionic Water-based Coating Hydrophilic layer formation with zwitterions Simultaneously achieving antifouling and antibacterial properties Low oil repellency 3‑4 2032
MOF Base Super Hydrophobic Mesh Ultraporous membrane of metal organic framework Breathable 40,000 g/m² 24h Cannot be mass-produced 2‑3 2035
Atmospheric pressure plasma room temperature deposition Silanes are surface polymerized Zero solvent Large equipment costs 6‑7 2026
Recyclable organosilan Reversible silane bonds Peeling → Easy to re-coat Heat resistance: 80℃ limit 4 2031

11‑1. Regulatory scenarios and market impacts

  • EU ...PFAS restrictions will be adopted in 2025 and implemented in 2030. High-performance fluorine is only available only for medical and aviation.
  • US EPA ... TSCA's new chemical substance review has been strengthened, and safety testing has been requested for nano-SiO2.
  • Japan ...It is scheduled to be designated by fiscal year 2027 by the Green Purchasing Act.

11‑2. Product image 10 years from now

  1. A smart label that visualizes "film thickness, water repellent performance, and installation date" with a QR code.
  2. Home desktop plasma coater DIY Nano Water Repellent is popular.
  3. Water-soluble graphene dispersion Repeat washing OK Clothing coating.
  4. A maintenance app that automatically detects water-repellent deterioration through AI image analysis.

While "disappearing coatings" that combine environmental and performance become the mainstream,Wear-resistant and oil-repellent functionThe next research topic is how to ensure this.

 

12. FAQ 50 questions

# question answer
1 How long should the waterproof spray be kept if it is unopened? The approximate date is generally three years from production. High temperature storage speeds up deterioration.
2 What about after opening? It is recommended to use it within a year. The propellant slowly drops and the pressure drops.
3 How many bags can one be installed? Approx. 2 m in a 300 ml can2。BackpackThen 8-10 units.
4 What if it hits the rain right after spraying? There is a risk that the uncured film will be whitened. Wipe dry and reinstall.
5 How many hours after installation does it have the most effective? It cures fully at 3h in solvent-based systems and 24h in aqueous systems.
6 For commuting Business bag Which type is best for? Odorless, thin film fluorine C6 or PFAS-free aqueous polymer.
7 Can it be used on PU leather? Water-based PU type is acceptable. Solvent systems extract plasticizers and cause surface cracking.
8 Does suede not become darker in colour? Low-pressure mist + double coatings minimize darkening.
9 Recommended for canvas totes? The silicone-based material easily penetrates and is water-repellent for a long time.
10 Can I apply fluorine and silicon overlay? This is deprecated as it may cause interface separation.
11 What is the optimum temperature and humidity during installation? Ideally a temperature of 15-25°C and humidity of 40-60%.
12 Does it dry even in winter? The hardening slows below 5°C, so the temperature is returned to room temperature before installation.
13 What about hot summers? To prevent condensation, it is less likely to occur if done early in the morning or evening.
14 Will the construction surface be sticky? Excessive spray amount. Lightly tap it with a dry cloth to remove excess.
15 How to reset if unevenness occurs? Degreas the whole thing with a leather cleaner → 24 h Dry → Re-apply.
16 Do you shake the can when installing? Shake only the products with stirring balls. Use the can that is instructed not to shake.
17 Is the can too cold and the spray is weak? Place at room temperature for 30 minutes to return the pressure.
18 Can you spray it upside down? Only products with check valves are acceptable. General cans will leak.
19 Will it completely block the leather's breathing? With thin film fluorine, the oxygen permeability remains at about -20% of the raw material.
20 How do I remove the peeled film? For leather, cleaner and brush. The fabric is almost completely removed after washing at 40°C.
21 Does waterproof spray also help prevent stains? Fluorine and nano SiO₂, which have oil-repellent properties, can also repel mud and oil.
22 Can a bonfire spark burn the membrane? Pyrolysis occurs at temperatures above 200°C. The burnt marks will not return even after reinstalling.
23 Can it be used for masks and clothing? Not recommended for manufacturers as it reduces breathability. Please use a special product.
24 How can I check if it's PFAS free? Check the "Organic Fluorine Compound" section of the SDS. If you are unsure, contact the manufacturer.
25 When should you apply the leather-retaining cream after installation? The basic method is to apply lightly after 24 h.
26 Do I need gloves when installing? Since solvent-based products have a sebum degreasing effect, nitrile gloves are recommended.
27 Does the metal fittings discolor? Brass and copper alloys are subject to combustible solvents and have a risk of discoloration. Masking is required.
28 Does the leather feel stiff after spraying? Because the oil content temporarily disappeared. You can recover with lanolin cream.
29 Are you worried about the construction sound? Reflecting noise is reduced by performing it outdoors or under a ventilation fan.
30 What to do if there is a smell left? Sealing with newspaper and baking soda for 24 hours will speed up VOC adsorption.
31 How often do you reinstall? Use daily bags for 4-6 weeks. It lasts 2-3 months on weekend use.
32 Does waterproof film decompose with ultraviolet rays? The silicon film cracks at 250h UV. Fluorine and nano are highly weather resistant.
33 What should you be aware of the risk of flammability? Steam remains for 3 minutes after installation, completely blocking out fire.
34 Can I use it on my children's leather shoes? Only low odor PFAS-free products are acceptable. Avoid anything else.
35 How to store it? Avoid direct sunlight 5-35℃. Side-side down is a possibility that the propellant leaks.
36 Can I carry it on an aircraft? Aerosols cannot be checked in or carried on board.
37 Can't spray it even if the contents remain? Valve clogged. Soak in lukewarm water for 5 minutes and spray again to improve.
38 What is the advantage of a nozzle dedicated to upside-down injection? Evenly spraying is possible on the bottom and soles of the shoes. It is also less likely to leak liquid.
39 Can you completely prevent color transfer? Water repellent cannot prevent pigments caused by friction. We recommend using a liner for the interior of the bag.
40 Can it be used as a gloves or hat? Can be matched to the material. Water-based water repellent is recommended for wool hats.
41 Is it harmful to the human body? Avoid direct inhalation. Use outdoors or in well-ventilated areas.
42 Doesn't the construction sound cause trouble for the neighbors? It's fine for outdoor work during the day. Avoid night construction.
43 Can I continue to apply water-based and solvent-based? The order of water-based to solvent-based materials is the cause of membrane cracking. In reverse order it's relatively safe.
44 White powder has come to float? Bloom phenomenon. Remove with dry wipe and leather oil.
45 Has the fabric changed darker? Too much inhalation. You can dilute it and reinstall it or wash it with water.
46 How about a water repellent test? Drip a small amount of water from a cup and turn it into a bead.
47 Does the leather jacket have a reduced breathability? Thin film fluorine is roughly −15 to 20% of raw material.
48 What is the safety of spraying on your hands? Wash with soap. If it's a solvent-based solution, continue to disinfect alcohol.
49 What accessories are required for installation? Gloves, masks, masking tape, brushes.
50 The can is rusty, can it be used? Do not use as there is a risk of corrosion causing rupture.

13. Cowmono Links

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14. References

  1. Yano Economic Research Institute, "The Actual Situation and Outlook of Outdoor-Related Markets 2024" (2024‑03).
  2. European Chemicals Agency (ECHA) “Annex XV – Proposal for a Restriction on Per‑ and Polyfluoralkyl Substances (PFAS)” (2023‑02).
  3. ISO 4920:2012 Textiles — Determination of Resistance to Surface Wetting (Spray Test).
  4. JIS L 1092:2018 Waterproofing test method for fabrics and knitted fabrics (low water pressure method).
  5. JIS K 6404:2006 Plastic - Wear Test Method (Taber Type).
  6. Nature Sustainability 6, 1095–1103 (2023) “Self‑degrading Fluorinated Polymers for Transient Water Repellency”.
  7. MIT Department of Mechanical Engineering News Release “Graphene–Silica Hybrid Coating Retains Super‑hydrophobicity after 30,000 Flex Cycles” (2022‑10‑11).
  8. 3M Technical Bulletin TB‑FR‑2024‑01 “Fluorinated Repellent Chemistry: Performance & Regulatory Update”.
  9. DuPont Safety Data Sheet No. 6:2 FTOH (2023‑05 rev.).
  10. "Handbook of Leather Science," edited by the Japan Leather Technology Association, Maruzen Publishing (2021).

Author information

Yama (cowmono Owner)

Author name: Yama (cowmono Owner)

Occupation: Slowth lab representative

He is engaged in sales and marketing for apparel companies both in Japan and abroad over quarterly. He has a deep knowledge of fashion, sports, outdoor activities, and subculture.