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Neutral cure or acetoxy silicone

Updated: 23 October 2026

You open a window to clear the smell, or you watch a bead on a uPVC frame let go at the corner, and the tube only said Soudal silicone. Neutral cure or acetoxy silicone is the fork underneath that. Acetoxy paste releases acetic acid as it cures, which is the vinegar smell, and it is a poor match for PVC. Neutral paste cures with moisture and is the one these listings actually name when the title says Silirub LMN. Silence on an amazon.co.uk specification is not a neutral cure. The eight cartridges are listed on the [Soudal silicone comparison](/hub/fillers-adhesives-and-sprays/soudal-silicone). A qualifying purchase can earn a commission at no extra cost to you.

You open a window to clear the smell, or you watch a bead on a uPVC frame let go at the corner, and the tube only said Soudal silicone. Neutral cure or acetoxy silicone is the fork underneath that.

Our top picks

Soudal Silirub LMN white 300 ml

Best overall

Soudal Silirub LMN white 300 ml
9.3/10about £8.20
View offer
Soudal Trade multi-purpose white 3-pack

Best value

Soudal Trade multi-purpose white 3-pack
8.0/10about £12.30
View offer
Soudal Silirub LMN brilliant white

Rank 3

Soudal Silirub LMN brilliant white
7.2/10about £17.03
View offer
On this page
  1. 1.What the two cures do
  2. 2.Where each one belongs
  3. 3.What these eight listings actually print
  4. 4.Smell is not a quality score

What the two cures do

Both are moisture-curing silicones. An acetoxy sealant gives off acetic acid: you smell vinegar, and the fresh bead is acidic. Soudal’s Trade Multi-Purpose sheet describes that smell, tells you to ventilate, and says adhesion to PVC and concrete is not good. An acid remark on the sheet names copper. Lead is a general acetoxy caution, not a line these Amazon listings print. Silirub LMN means low modulus and neutral, not a higher grade of the trade tube. The LMN sheet is MEKO-free, names uPVC and metal profiles, and still says to ventilate. ISO 11600 F&G 25 LM, on one listing here, allows about ±25% movement. That is not the sanitary class S1 on the trade declaration. Neutral does not mean you can paint the bead, and it does not make the tube safe on marble.

Where each one belongs

Use a listing that prints neutral on uPVC or on a metal frame you do not want an acid cure against. The white LMN materials line names wood, metal, PVC and glass. The brilliant white LMN listing names PVC-u and is the only row that prints the 25 LM class. Ceramic and wood are where the trade bullets aim. Do not use the trade family on uPVC because the title says construction: the matching sheet excludes PVC, and concrete sits on the same list. If the fresh bead will sit on copper, do not reach for the acetoxy sheet. A blank Amazon cure field has not confirmed neutral. Keep LMN off the secondary seal of an insulating glass unit and off PVB film. A bathroom you cannot ventilate is a bad place for the vinegar cure. That wet-room choice is on the Soudal silicone bathroom page.
Soudal Silirub LMN white 300 ml

Testsieger

Soudal Silirub LMN white 300 ml
9.3/10about £8.20
View offer

What these eight listings actually print

Three listings name neutral: the white LMN single at £8.20 with 4.5 from 118 ratings, the clear LMN single at £8.54 with 4.7 from 67, and the brilliant white LMN row at £17.03, whose bullet says ISO 11600 F&G 25 LM. Its specification says three tubes. One review says the photo showed four and one arrived. Five trade multipacks leave the cure blank, at £9.80, £12.30, £12.31, £12.95 and £21.28. They do not print acetoxy or neutral. The matching sheet is acetoxy. Part numbers 121643 and 121644 are what the Amazon pages show, not a claim that the PDF prints those codes as acetoxy. Choose a listing that prints neutral for uPVC and for copper. Colour and tube count belong on the Soudal silicone buying guide.

Smell is not a quality score

Vinegar after a trade pack is the acetoxy cure doing what the sheet describes. One white 6-pack review said a strong smell lingered. That fits the sheet, and it is still a reason to ventilate a small room. Neutral is not odourless. The white LMN bullets say non-vinegary scent, and a reviewer still found the smell strong. Low odour means it is not the vinegar cure. Do not rank a tube by how little it smells on the day. The LMN sheet’s skin is about 7 minutes. The trade sheet’s skin is about 20 minutes. One trade listing prints 7 minutes anyway.

Common questions

How do I tell the cures apart in the hand?
Smell is the clue after you gun, not before. Vinegar points at acetoxy. The reliable check before you buy is the wording: neutral on the three LMN listings, and a blank cure field on the five trade multipacks. Then read the cartridge. The Amazon silence is not a test.
Can I use the trade multipack on uPVC?
Not on the evidence of the title. The Trade Multi-Purpose sheet says adhesion to PVC is not good. The Amazon specification does not name the cure, so you cannot claim the page said acetoxy, and you cannot assume neutral. Use an LMN listing that prints neutral unless the cartridge you are holding says otherwise.
Why does it smell of vinegar?
That is acetic acid leaving an acetoxy sealant as it moisture-cures. The trade sheet calls it a typical acetic smell and says to ventilate. A vinegar smell on a pack whose listing never used the word acetoxy is a reason to check you have the trade family, not proof the paste has failed.
What about copper, lead, and concrete?
The trade sheet’s acid remark names copper, and the sheet lists concrete among substrates with no good adhesion. Lead is a general acetoxy caution, not a line these Amazon listings print. Neutral LMN is the choice against uPVC and the metal profiles the LMN sheet names. Do not extend that to a sealed-unit edge.
Which cure for a window frame?
Neutral, low modulus, from a listing that says so. The white LMN single is the largest review sample and names PVC. The brilliant white LMN listing is the one that prints the 25 LM class, if the tube count matches the specification. An unnamed trade multipack is the wrong default for that frame.

Related pages

How to apply Soudal silicone

Best Soudal silicone

Soudal silicone

Soudal silicone for a bathroom: bath, basin, shower

Soudal silicone buying guide: cure, colour and pack

Sources

Public UK sources used for this comparison. Prices, stars and review counts are the amazon.co.uk figures stored for these eight listings. This order is the listing order, not a laboratory test.

  1. Silirub LMN technical data sheet (retrieved 22 October 2026)
  2. Silirub LMN UK declaration of performance (retrieved 22 October 2026)
  3. Trade Multi-Purpose Silicone technical data sheet (retrieved 22 October 2026)
  4. Trade Multi-Purpose declaration of performance (retrieved 22 October 2026)
  5. Soudal UK paint FAQ (retrieved 22 October 2026)
  6. Soudal UK natural-stone FAQ (retrieved 22 October 2026)
  7. GOV.UK construction-product marking table (retrieved 22 October 2026)
  8. Consumer Rights Act 2015 section 11 (retrieved 22 October 2026)