Printed Cotton Men's T-Shirts: Complete Production Guide for B2B Sellers

Understanding Printed Cotton T-Shirt Configurations: A Neutral Overview

When sourcing printed cotton men's t-shirts on Alibaba.com, buyers encounter multiple configuration options that significantly impact cost, quality, and production timelines. The Pattern Type: Printed combined with Material: Cotton represents one of the most common configurations in the apparel B2B market, but it's far from the only option available.

This guide takes an objective, educational approach to help you understand what this configuration means, when it makes sense for your business, and what alternatives you should consider. We're not here to tell you this is the "best" choice - we're here to give you the knowledge to make that decision yourself based on your specific market, budget, and brand positioning.

What Does 'Printed Cotton' Actually Mean?

The term "printed cotton t-shirt" encompasses a wide range of production methods, each with distinct characteristics:

Base Material: 100% cotton, cotton blends (60/40, 50/50 cotton-polyester), or organic cotton
Printing Method: Screen printing, Direct-to-Garment (DTG), Direct-to-Film (DTF), or heat transfer
Design Complexity: Single color logos, multi-color graphics, photorealistic images, or all-over prints
Order Volume: From single-piece samples to bulk orders of 10,000+ units

Understanding these variables is crucial because they directly affect your cost structure, minimum order requirements, and ultimately your competitiveness when you sell on alibaba.com to global buyers.

Printing Methods Comparison: Which Technology Fits Your Business Model?

The printing method you choose is arguably the most critical decision in your t-shirt production strategy. Each technology has specific strengths, limitations, and ideal use cases. Let's examine the four major methods available to alibaba.com seller operations.

Printing Methods Comparison Matrix for Cotton T-Shirts

Method	Best For	MOQ Range	Durability	Cost per Unit (Bulk)	Fabric Compatibility	Design Flexibility
Screen Printing	Bulk orders 50+ units, simple designs 1-5 colors	12-24 pieces minimum, 50+ for complex	Excellent - 50+ washes	$2-4 for 100+ units	100% cotton, cotton blends best	Limited - each color needs separate screen
DTG (Direct-to-Garment)	Small batches, detailed designs, photo-quality	No minimum, 1-12 pieces viable	Good - 30-40 washes before fading	$8-15 for small runs	100% cotton requires pretreatment	Excellent - unlimited colors, fine detail
DTF (Direct-to-Film)	Versatile orders, mixed fabrics, no pretreatment	No minimum, 1-24 pieces common	Very Good - 40-50 washes	$5-10 for small-medium runs	Cotton, polyester, blends, fleece, nylon	Excellent - unlimited colors, vibrant
Sublimation	All-over prints, sportswear, unlimited colors	24-50 pieces typical	Excellent - dye fused into fibers	$6-12 for medium runs	100% polyester ONLY - NOT cotton	Excellent - seamless all-over designs

Data compiled from Printful, Argus Apparel, and DTF Illinois industry guides ^[1]^[2]^[5]. Costs vary by region, order volume, and design complexity.

Screen Printing: The Bulk Order Champion

Screen printing remains the industry standard for large-volume production. The process involves creating a separate mesh screen for each color in your design, then pressing ink through the screens onto the fabric. This method delivers exceptional durability and vibrant colors, but comes with significant setup costs.

Key Advantages:

Lowest per-unit cost for orders 50+ pieces
Exceptional durability - prints last 50+ washes without significant fading
Vibrant, opaque colors even on dark fabrics
Well-established quality control standards across the industry

Key Limitations:

High setup cost - each color requires a separate screen ($25-50 per screen)
Not cost-effective for small batches or one-off orders
Limited design flexibility - gradients and photorealistic images difficult to reproduce
Longer production time due to screen creation and setup

DTG (Direct-to-Garment): The Small Batch Specialist

DTG printing works like an inkjet printer for fabric. Specialized printers spray water-based inks directly onto the garment, which are then absorbed by the fibers. This technology excels at reproducing intricate designs with unlimited colors.

Key Advantages:

No minimum order quantity - viable for single-piece production
Photo-quality detail with unlimited color combinations
Soft, lightweight print feel that doesn't crack or peel
Faster turnaround for small orders - no screen setup required

Key Limitations:

Higher per-unit cost compared to screen printing for bulk orders
Requires fabric pretreatment for 100% cotton (adds cost and time)
Color vibrancy can be inconsistent on dark fabrics without proper underbase
Less durable than screen printing - may fade after 30-40 washes with heavy wear

"Wet-on-wet DTG is fast, cheap, low quality. Wet-on-dry is slower, expensive, high quality with vibrant colors and sharp fine lines. The difference is night and day for professional results." ^[6]

DTF (Direct-to-Film): The Versatile Challenger

DTF is the newest mainstream printing technology, gaining rapid adoption since 2023. The process prints designs onto a special PET film, applies adhesive powder, then heat-presses the transfer onto the garment. This method combines advantages from both screen printing and DTG.

Key Advantages:

Works on cotton, polyester, blends, fleece, and nylon without pretreatment
No minimum order - viable for single pieces and bulk production
Vibrant colors with excellent durability (40-50 washes)
Faster production than screen printing for medium-sized orders

Key Limitations:

Can have a slightly shiny or plasticky feel if not pressed correctly
Quality varies significantly by supplier - supplier selection critical
Second pressing with parchment paper often needed to achieve matte finish
Newer technology - less established quality standards across suppliers

Reddit User• r/SCREENPRINTING

"For one-offs DTF makes most sense. Screen printing setup is expensive for small runs. The shiny look from pressing can be fixed with a second press using parchment paper - knocks the shine down and makes it matte." ^[7]

DTF vs DTG discussion on r/SCREENPRINTING, 2 upvotes

Sublimation: The Polyester Specialist (NOT for Cotton)

Sublimation printing uses heat to convert solid dye into gas, which then fuses with polyester fibers at the molecular level. This creates prints that are essentially part of the fabric itself.

Critical Warning: Sublimation only works on 100% polyester or high-polyester blends. It does NOT work on 100% cotton t-shirts. If your product configuration specifies cotton material, sublimation is not a viable option.

Key Advantages:

Prints become part of the fabric - cannot crack, peel, or fade
Unlimited colors with seamless all-over print capability
Smooth finish with no texture or feel on the fabric
Excellent for sportswear and performance apparel

Key Limitations:

Requires 100% polyester or minimum 65% polyester blend
Only works on white or light-colored garments (dye is transparent)
Not suitable for the printed cotton configuration discussed in this guide
Higher fabric cost compared to cotton alternatives

Reddit User• r/TShirt

"Sublimation if 100% polyester white shirt. DTG for everything else. That's the simple rule." ^[8]

Printing method selection discussion on r/TShirt, 1 upvote

Design File Requirements: Avoiding Costly Production Mistakes

One of the most common causes of production delays and quality issues in custom t-shirt manufacturing is improper file preparation. Understanding file format requirements before submitting your designs to alibaba b2b suppliers can save weeks of back-and-forth communication and prevent costly reprints.

Design File Requirements by Printing Method

Printing Method	Preferred Formats	Minimum Resolution	Color Mode	Background Requirement	Special Notes
Screen Printing	AI, EPS, SVG (vector)	N/A - vector scales infinitely	CMYK or Pantone (PMS)	Transparent or white	Each color needs separate layer for screen separation
DTG	PNG, TIFF (raster)	300 DPI at actual print size	RGB	Transparent (mandatory for dark shirts)	White underbase required for dark fabric printing
DTF	PNG, SVG, TIFF	300 DPI at actual print size	RGB	Transparent recommended	No pretreatment needed, works on all colors
Sublimation	PNG, TIFF, AI	300 DPI at actual print size	RGB	Transparent or white	Design mirrors during printing - account for this

File requirements compiled from T-Shirt Elephant, Printful, and Transfer Kingdom guidelines ^[3]^[9]^[10]. Always confirm with your specific supplier before production.

Understanding DPI Resolution Requirements

DPI (Dots Per Inch) is the single most important technical specification for raster image files. The industry standard is 300 DPI at actual print size - this is not negotiable for professional-quality results.

Practical Examples:

Small 3"x3" chest logo: Minimum 900x900 pixels
Medium 8"x10" back print: Minimum 2400x3000 pixels
Large 12"x14" full back: Minimum 3600x4200 pixels

A common mistake is creating artwork at screen resolution (72 DPI) then expecting it to print well. This results in pixelated, blurry prints that damage your brand reputation. Always create or export files at 300 DPI from the start.

Vector vs. Raster: When to Use Each

Vector Formats (AI, EPS, SVG, PDF):

Use for logos, text, and simple graphics
Scale infinitely without quality loss
Required for screen printing color separation
File size remains small regardless of design size

Raster Formats (PNG, TIFF, JPEG):

Use for photographs, gradients, and complex artwork
Fixed resolution - cannot scale up without quality loss
Required for DTG and DTF printing
PNG with transparency essential for dark garment printing

Critical Mistake to Avoid: Never submit JPEG files for t-shirt printing unless explicitly approved by your supplier. JPEG compression creates visible artifacts that become obvious when printed on fabric.

Google Featured Snippet• Transfer Kingdom Blog

"PNG is the go-to format for most t-shirt designs thanks to its transparent background support and high quality. Always use transparent backgrounds for DTG printing on dark shirts." ^[11]

Print-ready file formats guide, featured in Google People Also Ask

Color Mode Confusion: RGB vs. CMYK vs. Pantone

Different printing methods require different color modes, and using the wrong one can result in significant color shifts:

RGB (Red, Green, Blue): Use for DTG and DTF printing. Digital printers are calibrated for RGB color space.
CMYK (Cyan, Magenta, Yellow, Black): Use for screen printing process colors. Matches the ink mixing system.
Pantone (PMS): Use for screen printing spot colors when exact brand color matching is critical. Each Pantone color requires a separate screen.

When working with alibaba.com suppliers, always specify your color mode requirements upfront and request a physical color proof before full production runs.

MOQ and Pricing Tiers: Understanding the Economics

Minimum Order Quantity (MOQ) is often the deciding factor for businesses choosing between printing methods. Understanding MOQ structures helps you align your production strategy with your business model and cash flow capabilities.

MOQ and Pricing Structure by Order Size

Order Size	Recommended Method	Typical MOQ	Cost per Shirt (Cotton)	Setup Costs	Best For
1-12 pieces	DTG or DTF	No minimum	$12-20 per shirt	$0-25	Samples, prototypes, one-off custom orders
12-24 pieces	DTG, DTF, or Screen	12-24 pieces	$10-15 per shirt	$25-100	Small teams, test runs, crowdfunding rewards
25-49 pieces	Screen or DTF	Varies by supplier	$8-12 per shirt	$50-200	Small businesses, local events, starter inventory
50-99 pieces	Screen Printing	50+ pieces optimal	$6-9 per shirt	$100-300	Established small brands, retail inventory
100-299 pieces	Screen Printing	100-300 standard	$5-7 per shirt	$200-500	Growing brands, wholesale orders
300+ pieces	Screen Printing	300+ for best pricing	$3-5 per shirt	$300-800	Large brands, distributor orders, corporate bulk

Pricing data from Underground Printing, Real Thread, and Printful profit analysis ^[4]^[12]^[13]. Costs vary by region, fabric quality, and design complexity.

Understanding MOQ Variations by Supplier

MOQ requirements vary significantly across the manufacturing landscape:

Most screen printing suppliers set MOQs between 12 and 24 shirts for custom orders. This range balances efficient production with reasonable cost for the buyer. However, some decorators may require minimums of 50 or more shirts for a single design to justify setup costs ^[12].

Factors That Influence MOQ:

Setup Costs: Screen creation is required for each color in your design. This fixed cost is incurred regardless of order quantity, making small orders disproportionately expensive.
Design Complexity: More colors = more screens = higher setup cost = higher MOQ. A 6-color design may have a 50-piece MOQ while a 1-color design could be 12 pieces.
Supplier Policies: Different manufacturers have different business models. Some specialize in low-MOQ startup support, others focus exclusively on bulk corporate orders.
Fabric Availability: If your chosen blank t-shirt style/color requires special ordering from the manufacturer, MOQ may increase to meet their minimum fabric purchase requirements.

Pricing Tiers and Profit Margins

For alibaba.com seller operations targeting Southeast Asian and global markets, understanding pricing tiers is essential for competitive positioning:

Custom Cotton T-Shirt Base Costs:

Basic custom cotton shirts: $7-10 per garment starting point
Tri-blend premium tees: $9-13 per garment starting point
Organic cotton options: $10-15 per garment starting point

Typical Profit Margins: Most sellers earn between $3-8 profit per shirt, or 30-50% profit margins when priced correctly ^[13]. This varies significantly based on:

Target market (B2B wholesale vs. B2C retail)
Brand positioning (budget vs. premium)
Order volume (bulk discounts improve margins)
Value-added services (custom packaging, labeling, fulfillment)

Google Featured Snippet• Underground Printing

"Most screen printing suppliers set MOQs between 12 and 24 shirts for custom orders. This range balances efficient production with reasonable cost for the buyer." ^[12]

MOQ guide for screen printed shirts, March 2026

Alternative Options for Low-MOQ Needs

If your business model requires flexibility below traditional screen printing MOQs, consider these alternatives:

DTG Printing: No minimum order, excellent for detailed designs and photo-quality prints. Ideal for print-on-demand businesses and startups testing designs.

Screen Print Transfers: Combine screen printing quality with flexible ordering. Order transfers in bulk, then press onto garments as needed. Less upfront minimum than direct screen printing.

Embroidery: Higher minimum for small stitch areas, but premium positioning justifies higher price points. Excellent for logos and brand marks on polo shirts and caps.

The key is matching your production method to your business stage and market strategy, not forcing a configuration that doesn't fit your operational reality.

Quality Control: What Buyers Really Care About

Quality control in printed t-shirt manufacturing extends far beyond visual inspection. Understanding what buyers actually evaluate helps you prioritize quality investments that matter.

Durability Testing Standards

Different printing methods have vastly different durability profiles:

Screen Printing and Sublimation: Last longest with proper curing. Screen prints withstand 50+ washes with minimal fading. Sublimation dyes fuse into fibers and cannot crack or peel ^[5].

DTF: Very good durability (40-50 washes) when applied correctly. Quality varies significantly by supplier - this is where supplier vetting becomes critical.

DTG: Good durability (30-40 washes) but fades faster than screen printing with heavy wear. Water-based inks absorb into fibers but can fade with repeated washing and sun exposure ^[5].

Heat Transfer Vinyl (HTV): May peel over time, especially with frequent washing. Best for simple text and shapes, not large solid areas.

Reddit User• r/TShirt

"Screen printing most durable, best for bulk orders especially simple designs. DTG good for detailed prints and smaller quantities. That's the trade-off." ^[14]

Printing methods discussion on r/TShirt community, 1 upvote

Common Quality Issues and How to Avoid Them

DTG-Specific Issues:

White Underbase Haloing: On dark garments, DTG requires a white underbase layer. If misaligned, this creates a visible white halo around your design. Caused by improper curing or misalignment during printing ^[6].
Banding on Solid Colors: Horizontal lines appearing in solid color areas. Usually caused by clogged print nozzles or incorrect print head calibration.
Color Vibrancy Issues: Colors appearing dull or washed out. Often caused by incorrect pretreatment application or improper curing temperature.
Scratching/Cracking: Print surface scratches off easily. Indicates under-curing - the ink wasn't heated long enough or at the correct temperature ^[6].

DTF-Specific Issues:

Shiny/Plasticky Feel: DTF transfers can have a glossy appearance if not pressed correctly. Solution: Second press with parchment paper knocks shine down and creates matte finish ^[7].
Peeling at Edges: Transfer adhesive didn't fully bond. Caused by insufficient heat, pressure, or pressing time during application.
Color Bleeding: Colors spreading beyond design boundaries. Usually indicates poor quality transfer film or incorrect heat press settings.

Screen Printing Issues:

Ink Bleeding: Ink spreading beyond intended boundaries. Caused by excessive pressure, wrong mesh count, or ink viscosity issues.
Pinholes: Small uncovered spots in solid ink areas. Caused by dust on screens, incomplete emulsion coverage, or ink contamination.
Color Registration Errors: Multi-color designs where colors don't align properly. Caused by screen misalignment during setup.

Pre-Production Quality Verification Checklist

Before approving full production runs, request and verify:

Physical Color Proof: Actual printed sample on your chosen fabric, not digital mockup
Wash Test Report: Supplier should provide wash test results showing durability after 20-30 washes
Fabric Composition Certificate: Verify cotton percentage matches specifications (100% cotton vs. blends)
Print Placement Measurements: Confirm print location, size, and alignment match your requirements
Packaging Inspection: Verify labeling, folding, and packaging meet your brand standards

For alibaba.com transactions, leverage the platform's inspection services for orders above $5,000. Third-party inspection adds 1-2% to order cost but prevents costly quality disasters.

Industry Forum Member• DTF Illinois Blog

"Screen printing and sublimation last the longest. DTF is close behind if applied correctly. DTG tends to fade faster on heavy wear garments. HTV may peel over time." ^[5]

Durability comparison guide for t-shirt printing methods

Configuration Decision Guide: Choosing the Right Setup for Your Business

There is no single "best" configuration for printed cotton t-shirts. The optimal choice depends on your specific business context. This decision framework helps you evaluate options systematically.

Business Type to Configuration Recommendation Matrix

Business Profile	Recommended Method	MOQ Strategy	Fabric Choice	Key Priority	Avoid
Startup testing designs	DTG or DTF	No minimum, order 1-12 pieces	100% cotton or blends	Flexibility, low risk	Screen printing (high setup cost)
Small brand 50-200 units/month	Screen or DTF	24-50 pieces per design	100% cotton preferred	Balance cost and quality	Sublimation (wrong fabric type)
Established brand 500+ units/month	Screen Printing	100-300 pieces per design	Cotton or cotton blends	Lowest per-unit cost	DTG (too expensive at scale)
Print-on-demand business	DTG or DTF	Single piece fulfillment	Various based on product	No inventory risk	Any method requiring bulk MOQ
Corporate/bulk orders	Screen Printing	300+ pieces per order	Standard cotton tees	Durability, brand consistency	Methods with quality variation
Premium/luxury positioning	Screen or Embroidery	50-100 pieces minimum	Organic or premium cotton	Quality over cost	Budget printing methods

Recommendations based on industry analysis from Printful, Argus Apparel, and Underground Printing ^[1]^[2]^[12].

Decision Factors Framework

When evaluating configuration options, consider these five factors in order of importance:

1. Order Size and Frequency

One-off or <24 pieces: DTG or DTF
25-99 pieces: DTF or Screen (depending on design complexity)
100+ pieces: Screen printing for best economics
Recurring small orders: DTF offers best balance

2. Budget Constraints

Limited startup capital: Start with DTG/DTF, scale to screen as volume grows
Established budget: Screen printing maximizes ROI at volume
Premium positioning: Higher cost per unit acceptable for quality

3. Design Complexity

Simple logos 1-3 colors: Screen printing most cost-effective
Detailed artwork, gradients, photos: DTG or DTF required
All-over prints: Sublimation (but requires polyester, not cotton)

4. Fabric Requirements

100% cotton: Screen, DTG, or DTF all viable
Cotton-poly blends: All methods work, DTF most versatile
100% polyester: Sublimation optimal, but outside cotton configuration scope

5. Brand Positioning

Budget/value: Screen printing at volume, DTF for small runs
Mid-market: Balance of quality and cost, DTF increasingly popular
Premium: Screen printing with premium blanks, or embroidery for logos

When Printed Cotton May NOT Be Your Best Choice

Honesty matters in business decisions. The printed cotton configuration discussed in this guide is excellent for many use cases, but not all. Consider alternatives when:

Your target market prefers performance fabrics: Athletic wear, gym apparel, and outdoor activities often require moisture-wicking polyester blends. Sublimation on polyester may serve these markets better.

You need all-over prints: Sublimation is the only method that truly delivers seamless all-over printing. Cotton limits you to standard print areas (chest, back, sleeves).

Your customers prioritize eco-sustainability: Organic cotton with water-based DTG inks has lower environmental impact than traditional screen printing with chemical emulsions. However, DTF's adhesive powders and plastic films raise sustainability questions ^[5].

You're targeting ultra-premium luxury markets: Embroidery on high-end blanks may command higher price points and better align with luxury brand expectations than printed graphics.

Why Southeast Asian Sellers Choose Alibaba.com for Printed T-Shirt Sourcing

For merchants in Southeast Asia looking to sell on alibaba.com or source printed t-shirts for their businesses, the platform offers distinct advantages over traditional sourcing channels.

Global Buyer Network Access

Alibaba.com connects you directly with B2B buyers from 190+ countries, eliminating the need for expensive trade show participation or building your own international sales infrastructure. For printed t-shirt suppliers, this means:

Access to bulk order buyers (corporate uniforms, event merchandise, retail chains)
Exposure to markets with higher price tolerance (North America, Europe, Australia)
Year-round inquiry flow vs. seasonal trade show cycles
Verified buyer profiles reducing fraud risk

Technology-Enabled Matching

The platform's algorithm matches your product listings with buyers actively searching for printed cotton t-shirts, custom apparel, and graphic tees. This intent-based matching is far more efficient than cold outreach or generic advertising.

Trade Assurance Protection

For orders placed through Alibaba.com, Trade Assurance provides payment protection and quality dispute resolution. This builds buyer confidence when working with new suppliers - a critical factor in B2B apparel sourcing where quality variations can be significant.

Competitive Intelligence Tools

Alibaba.com provides data insights that help you optimize your product listings:

Keyword performance data showing what buyers are searching for
Competitor pricing analysis for similar printed t-shirt configurations
Seasonal demand trends to plan production capacity
Geographic demand distribution to target marketing efforts

Streamlined Communication

The platform's messaging system supports:

File sharing for design proofs and specifications
Translation services for cross-language communication
Order tracking and milestone updates
Dispute resolution documentation trail

For Southeast Asian exporters, these tools reduce the friction of international B2B commerce and enable smaller suppliers to compete effectively with larger manufacturers.

Getting Started on Alibaba.com

If you're considering listing printed cotton t-shirts on the platform:

Optimize Your Product Configuration: Clearly specify printing method, fabric composition, MOQ, and available sizes/colors
Showcase Quality Proof: Include photos of actual printed samples, not just mockups
Be Transparent About Capabilities: State your realistic production capacity and lead times
Offer Samples: Enable sample orders to build trust with new buyers
Leverage Verified Supplier Status: Invest in verification badges that increase buyer confidence

The printed cotton t-shirt market on Alibaba.com is competitive but substantial. Success comes from clear positioning, consistent quality, and reliable fulfillment - not from being the lowest-priced option.

Action Plan: Next Steps for Your Printed T-Shirt Business

Based on the analysis in this guide, here's a practical action plan for merchants evaluating printed cotton t-shirt configurations:

For New Sellers (First-Time Exporters):

Start with DTF or DTG printing to minimize upfront investment and test market demand
Order samples from 3-5 suppliers on Alibaba.com to compare quality firsthand
Begin with MOQs of 12-24 pieces per design to limit inventory risk
Focus on 1-2 core designs rather than broad catalog initially
Request physical color proofs before approving any production run
Budget for 30-50% profit margins to allow for pricing flexibility

For Growing Sellers (Scaling Operations):

Transition to screen printing once you consistently order 50+ pieces per design
Negotiate volume pricing with 2-3 preferred suppliers for redundancy
Invest in quality control - consider third-party inspection for orders above $5,000
Develop standard operating procedures for file preparation and quality verification
Build inventory of popular designs to reduce lead times for repeat orders
Explore value-added services (custom packaging, labeling, dropshipping) to differentiate

For Established Sellers (Optimizing Margins):

Consolidate orders to maximize volume discounts (300+ pieces per production run)
Negotiate exclusivity agreements with suppliers for unique designs or fabrics
Implement batch production schedules to optimize supplier capacity utilization
Develop private label relationships for custom blank t-shirts with your branding
Use Alibaba.com data analytics to identify emerging design trends and market opportunities
Consider vertical integration (bringing printing in-house) if volume justifies equipment investment

Key Success Metrics to Track:

Order Fulfillment Time: Target 7-14 days for samples, 15-30 days for bulk production
Defect Rate: Should be below 2% for established supplier relationships
Repeat Order Rate: Above 40% indicates strong product-market fit
Profit Margin: Maintain 30-50% for sustainable business growth
Customer Satisfaction: Monitor reviews and feedback for quality issues

Red Flags to Watch For:

Suppliers unwilling to provide samples before bulk orders
Prices significantly below market average (quality compromise likely)
Vague responses to technical questions about printing methods
No quality control documentation or wash test reports
Pressure to pay 100% upfront without Trade Assurance protection

The printed cotton t-shirt market offers substantial opportunity for Southeast Asian exporters on alibaba.com. Success requires understanding the technical details covered in this guide, but more importantly, building reliable supplier relationships and maintaining consistent quality standards.