Should You Deep Condition With Heat? Does It Make A Difference?

What’s the best way to deep condition your hair so that you receive the maximum benefit? Once you’ve selected your treatment, there is still the question of whether you should deep condition with heat to help the ingredients penetrate your hair.

  • Does it make the mask go deeper?
  • Does your hair absorb more moisture this way?
deep conditioning without heat

The answer will depend on your hair type, and specifically, your porosity level.

I have a porosity quiz that you can take to help determine your level.

You may not need to apply heat depending on your hair type! 

I have grouped low and medium porosity – they are the most similar of the levels and can be treated similarly for deep conditioning.

Low or Medium Porosity Hair


  • Hair that has not been subjected to frequent mechanical stress or chemical processes. You haven’t heat styled or coloured your hair regularly.
  • Your hair takes a long time to dry.
  • Your hair is weighed down easily by products like serums and oils.
  • Your hair is shiny

Low and medium porosity hair is generally in good condition. 

The overlapping ‘scales’ that form the hair’s cuticle layer lie flat or nearly flat. This is what gives the hair shine.

Low porosity hair retains moisture well, but it can be difficult to add more moisture because the smooth, flat cuticle acts as a barrier.

low porosity hair needs heat when you deep condition

High Porosity Hair

  • It can be genetic but frequently the result of damage from heat or chemical processes such as colouring
  • Your hair dries quickly
  • Your hair tends to absorb oils and serums well. It is ‘thirsty.’
  • It has a dry, often brittle texture
  • Dull-looking

The overlapping scales that form the hair’s cuticle layer are raised, chipped, or missing altogether.

The lack of a smooth surface is why the hair can be dull-looking. 

The chipped or missing cuticle scales mean that the hair is generally weaker and can be brittle in texture.

High porosity hair loses moisture quickly through the cuticle’s gaps but takes on moisture readily, too, as the cuticle does not provide a barrier.

high porosity hair doesn't need heat when deep conditioning

How Does The Porosity Level Affect Deep Conditioning?

The deep conditioner’s ability to penetrate the hair determines how effective it will be. We need to ensure that the moisturising ingredients can penetrate the hair.

If a deep conditioning treatment remains on the hair’s surface, it won’t fulfil its moisturising duties.

Low and Medium Porosity Deep Conditioning

The barrier created by the smooth, flat cuticle layer means that deep conditioners will have difficulty penetrating the hair strand.

If you have low porosity hair, should you deep condition with heat?

We can enable penetration of the strand by enlisting the help of heat.

The heat will lift the cuticle layers, allowing the deep conditioner to pass through and into the hair’s cortex.

The heat can be applied in various ways. It is always best to start by putting a plastic cap or old shower cap over your hair once you have washed it and applied deep conditioner. The cap creates a ‘greenhouse’ effect for your hair, amplifying the heat. 

  • Apply heat with a hairdryer by moving it around your head once the cap is on
  • Cover the cap with a second ‘heat cap’. These are usually placed in the microwave to heat them before placing them over your hair
  • Using a hooded dryer

How Long For?

Apply heat for anywhere between 15 and 30 minutes to give the treatment time to sink in. Then rinse it out.

High Porosity Deep Conditioning

The open nature of the cuticle layer means that deep conditioners will be able to penetrate your hair strands easily.

If you have high porosity hair, should you deep condition with heat?

There is no need to use heat when deep conditioning. Apply the deep conditioner to wet, shampooed hair and leave it.

How Long For?

Leave the treatment on for 15 minutes to penetrate through the cuticle and reach the cortex.

Can I Leave The Deep Conditioner On Overnight?

Deep conditioner should not be left on overnight.

Once the deep conditioner has penetrated your hair, it will not be able to do any more good. Leaving it on for longer won’t achieve better results.

If your hair doesn’t feel better once you have used it for the times recommended above, it means that this is not the best deep conditioner for your hair. 

If you have low porosity hair, you won’t be able to (and wouldn’t want to!) keep heat on your hair overnight so the conditioner will stop working once heat is removed and the cuticle layer has lowered. 

If you have high porosity hair there is an even bigger issue.

You are likely to over-moisturise your hair if you leave the conditioner on overnight.

It is 100% possible to over-moisturise your hair. This is called ‘hygral fatigue’, and it can be very damaging.

When we wash high porosity hair, it takes on water through the porous surface and expands as it does so. When your hair dries and the water is lost, it contracts again.

This regular expansion and contraction is damaging to the already weakened hair strand. We need to reduce the amount of time the hair spends in the wet, expanded state.

When a deep conditioning treatment is left on wet hair overnight, the hair is expanded the whole time. We are actually causing our hair more damage when we do this.

This applies to any treatment applied to wet hair and includes bond-rebuilding treatments such as Olaplex.

Can I Deep Condition On Dry Hair?

You should apply deep conditioning masks to wet hair that has been washed. This makes sure there are no additional barriers to the treatment. Shampooing will remove any products or oils that are on your hair.

If you tried to do a deep conditioning treatment on dry hair that already has a leave-in conditioner, cream applied, for example, you wouldn’t be getting the best results. These products will block the deep conditioner and prevent it from penetrating the hair strand. 

The only kind of treatment you should apply to dry hair is a pre-poo oil treatment because oil and water won’t mix.

If you tried to do a pre-poo treatment on wet hair, the oil wouldn’t be able to penetrate the strands.

This means that pre-poo treatments can be left on overnight. 

The guidelines for heat on conditioning masks can also be applied to pre-poo treatments. Adding heat to low porosity hair will help the oil to penetrate the strands.

I hope that this guide has been helpful and answers the question of whether you should deep condition with heat!

My Favourite Treatments

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My favourite deep conditioner

Noughty To The Rescue Intense Moisture Treatment

noughty deep conditioning mask

A thick, rich mask full of moisturising ingredients like shea butter and coconut oil. I use this every 2 weeks.

Microwaveable Heat Cap

Pop it in the microwave and then over one of the supplied plastic caps to add heat to your conditioning routine.

My favourite pre-poo oil. I am currently using Hair Loving Hair Hydration Oil. It’s a blend of castor oil, grapeseed oil, sweet almond oil, ginger oil, vitamin E and avocado oil.

You can use my code LAUREN10 to receive 10% off the oil ❤️

hair loving oil pre-shampoo treatment

Lauren xx