What does the one-dot iron symbol mean?

The iron symbol with one dot means use a low heat setting — up to 110°C (230°F), the "synthetic" or "nylon" setting on most irons. This applies to heat-sensitive synthetic fibres like nylon, acetate, acrylic, and triacetate that distort or melt at temperatures above 120°C. It also applies to silk, which requires a completely dry iron (no steam) and a pressing cloth to prevent surface marking.

What happens if I iron too hot on a low-heat fabric?

High or medium heat on a single-dot fabric causes immediate, irreversible damage: nylon and acetate melt and deform permanently; polyester and synthetics develop a permanent glazed sheen where the iron contacted the surface; silk develops heat-set discolouration. Unlike slight scorching on cotton (which sometimes fades), these marks on synthetic fabrics are completely permanent and ruin the garment.

Can I use steam when ironing on low heat?

No — do not use steam at the single-dot setting. At 110°C, steam creates water droplets on the fabric surface before they evaporate fully. On silk and acetate, these dry as permanent water spots or ring marks that are extremely difficult or impossible to remove. Use a completely dry iron, and empty the water reservoir before ironing to prevent any residual moisture from escaping as steam.

What does Iron Low Heat mean?

Ironing230°F (110°C)medium risk

Quick Answer

The iron low heat symbol (an iron outline with one dot) means iron at no more than 110°C — equivalent to 230°F, the coolest setting on most irons. This applies to heat-sensitive synthetics such as nylon, acetate, and acrylic, as well as silk. It is safest to iron without steam, keep the iron moving constantly, and place a pressing cloth between the iron and the garment to prevent scorching.

Also known as: one dot iron symbol, low heat iron symbol, synthetic iron setting, 110°C iron symbol, cool iron sign, silk iron symbol

Important Warning

Higher heat will melt or damage fabric

Detailed explanation

The iron low heat symbol (an iron icon with one dot) corresponds to a maximum of 110°C (230°F) — the lowest setting on most irons, typically labelled "Synthetic" or "Nylon". This temperature applies to heat-sensitive synthetic fibres — nylon, acetate, and acrylic — that begin to distort, melt, or take on a permanent sheen at temperatures above 120°C. It also applies to silk, which technically tolerates slightly higher temperatures but is exceptionally prone to water spotting, making dry ironing with a pressing cloth the only safe approach. At this temperature, wrinkle removal requires patience and multiple passes.

How to follow the Iron Low Heat symbol:

1
Use lowest iron setting
2
No steam or very light steam only
3
Place cloth between iron and fabric
4
Move iron quickly - don't leave in one spot

When does this symbol appear on care labels?

For nylon, acetate, acrylic, and triacetate garments and linings
For silk garments where ironing is permitted by the care label (not all silk can be ironed)
For garments with heat-transfer printed designs
For thin synthetic fabrics such as polyester chiffon and synthetic georgette

Tips and Best Practices

Iron without steam at this temperature — steam creates water droplets that mark silk and acetate before they evaporate, leaving permanent water spots
Use a pressing cloth as standard practice — even at 110°C, direct iron contact on silk or acetate can cause irreversible surface marks
Keep the iron moving constantly — at low temperatures the risk is lower, but silk and acetate can still mark if the iron dwells too long
Allow the iron to stabilise at the low setting before using — many irons are still descending from a higher temperature for the first few minutes
For silk, iron on the wrong side only — this provides effective wrinkle removal with almost zero risk of surface marking

What happens if this symbol is ignored

Using higher heat on single-dot-rated synthetics causes immediate and irreversible damage: melting and permanent distortion on nylon and acetate, a shiny scorch glaze on polyester, and permanent surface changes on other heat-sensitive fabrics. These marks cannot be removed.

Common mistakes to avoid

Using steam on silk — water spots from steam marks on silk are extremely difficult to remove
Leaving the iron stationary — even at low temperature, dwelling too long on delicate synthetics causes marks
Not using a pressing cloth on silk — always iron through a thin cotton cloth
Ironing on the right side of silk — always iron the reverse side for safety

Regional Note (US)

230°F - Low/synthetic setting on iron

Common Materials

SilkSyntheticsAcetateNylon

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If this symbol appears on linen or denim clothing, follow our step-by-step washing guides: How to wash linen · How to wash denim.

Frequently Asked Questions

Related Ironing Symbols

Iron High Heat

Iron at high temperature - up to 200°C (390°F)

Iron Medium Heat

Iron at medium temperature - up to 150°C (300°F)

Iron Without Steam

Iron without steam - dry iron only

Iron With Steam

Iron with steam allowed - steam is safe to use

Do Not Iron

Do not iron - heat will damage the fabric

Iron Any Temperature

Iron at any temperature setting

Often used together

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