OTTOSEAL S100 vs. S105 compared
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What you need
Project template “Renew the silicone joint in the bathroom”Short answer: OTTOSEAL S100 is OTTO Chemie's premium sanitary silicone with a particularly easy-to-tool surface, additional bacteriostatic protection and over 70 shades – ideal for visible joints and high visual demands. OTTOSEAL S105 is the cheaper variant, tested to the current EN 15651, with a fungicidal additive and available in over 30 shades – enough for most standard sanitary joints. For tiles with high demands or particularly visible joints we recommend the S100; for budget-conscious standard projects the S105 is perfectly adequate. For natural stone neither is suitable – there a neutral-curing natural stone silicone such as OTTOSEAL S 70 or S 117 belongs in the joint.
OTTOSEAL S100 vs. S105 – the two sanitary silicones from OTTO Chemie compared
Both silicones come from the same manufacturer, OTTO Chemie, and are developed for sanitary areas: sealing and jointing at basins, showers, baths, tiles and masonry. The difference does not lie in the basic principle – both are acetoxy-curing 1K silicone sealants – but in working quality, certification, colour range and price. Anyone who has worked with both side by side notices the difference above all when tooling the joint.
OTTOSEAL S100 Premium sanitary silicone
- Fungicidal and bacteriostatic additives
- Outstandingly easy-to-tool surface, very good adhesion on ceramics
- Complies with DIN 18545, part 2, group E
- TOXPROOF seal from TÜV Rheinland (low-emission building product)
- Over 70 shades in the 300 ml cartridge
OTTOSEAL S105 sanitary silicone
- Fungicidal additive, resistance to mould growth
- Tested to EN 15651 (parts 1, 2 and 3)
- EMICODE EC1 Plus – very low-emission, French VOC class A+
- Cheaper than the S100 while solidly meeting the standard
- Over 30 shades in the 310 ml cartridge
Detailed comparison
| Feature | OTTOSEAL S100 | OTTOSEAL S105 |
|---|---|---|
| Base | Acetoxy-curing 1K silicone | Acetoxy-curing 1K silicone |
| Additives | Fungicidal and bacteriostatic | Fungicidal |
| Standard / test | DIN 18545, part 2, group E; IVD guidance note no. 3 | EN 15651 part 1 (F EXT-INT CC 25LM), part 2 (G CC 25LM), part 3 (XS1); IVD guidance note no. 3-1+3-2+14+31+35 |
| Certificates | TOXPROOF seal TÜV Rheinland | REACH-compliant, EMICODE EC1 Plus, French VOC class A+, reaction to fire EN 13501 class E |
| Application | Unique working properties, outstandingly easy-to-tool surface | Good to work with, standard tooling behaviour |
| Application temperature | +5 °C to +35 °C | +5 °C to +35 °C |
| Shelf life | At least 18 months, cool and dry | At least 18 months, cool and dry (< 60 % RH, +15 °C to +25 °C) |
| Supplied as | 300 ml cartridge, 400 ml sausage pack | 310 ml cartridge, 400 ml aluminium foil pack |
| Shades (310/300 ml) | Over 70 shades | Over 30 shades |
| Price level | Premium price segment | Cheaper |
Which silicone for which use case?
- Visible joints in living areas with high visual demands
- A need for an unusual shade from the large colour palette
- Re-sealing where a particularly smooth, clean joint surface is wanted
- Wet rooms with an increased risk of mould (additional bacteriostatic protection)
- Standard sanitary joints in bathroom, WC and kitchen with no special extra requirement
- Budget-conscious projects, rented flats or larger areas for instance
- When a standard colour from the over 30 shades is enough
- A wish for particularly low-emission material (EMICODE EC1 Plus)
A tip from practice: both silicones can be applied with the same tools – hand gun, pneumatic gun or cordless gun, application temperature +5 °C to +35 °C in each case. Tool with tooling agent and a spatula before a skin forms, and the joint comes out clean with both products. How many cartridges you need for your project can be looked up in our Ottoseal silicone usage table.
Related guides: if you are still unsure which silicone is right for your shower, read our guide Which silicone for the shower?. And if mould is already visible in an old joint, our guide Preventing and removing mould in silicone joints shows how to get the problem under control before you re-seal.
You will find both silicones together with other joint sealants in our category sanitary silicone.
Common questions about OTTOSEAL S100 and S105
Is OTTOSEAL S105 just as good as the S100?
For the pure sealing function both are suitable – both are acetoxy-curing 1K silicones with a fungicidal additive. The S100 additionally offers bacteriostatic protection and a surface that tools particularly smoothly, and is tested to DIN 18545 part 2 group E, while the S105 is certified to the current EN 15651. For most standard applications the S105 is enough; where visual or hygiene demands are higher, the S100 is the better choice.
Which silicone lasts longer?
According to the manufacturer both products keep for at least 18 months when stored cool and dry and are designed for lasting interior and exterior use. A noticeable difference in the life of the finished joint shows up above all under mechanical and hygiene stress: the additional bacteriostatic additive in the S100 can be an advantage in very damp areas.
Can I combine the S100 and S105 in the same bathroom?
Technically that is no problem, as both products are built on the same silicone base. For a uniform visual result we nonetheless recommend sticking to one product per visible joint area (the shower, for instance), as gloss level and colour nuance can differ slightly between the ranges.
How many shades are there for the S100 and S105?
OTTOSEAL S100 is currently available in over 70 shades in the 300 ml cartridge, OTTOSEAL S105 in over 30 shades in the 310 ml cartridge. Both ranges are additionally available in larger aluminium foil packs and sausage packs (400 ml), where the colour choice is smaller.
Are both silicones mould-resistant?
Yes, both carry a fungicidal additive and are therefore designed to resist mould growth. OTTOSEAL S100 additionally carries a bacteriostatic additive, which offers a further protective mechanism against micro-organisms. With both it is important that old, already mouldy sealant is removed completely before re-sealing.
Which silicone is suitable for natural stone?
Neither of them. The S100 and S105 are acetoxy-curing and can permanently discolour the edge zones on marble, granite and other natural stones. For natural stone use a neutral-curing natural stone silicone such as OTTOSEAL S 70 (wall and sanitary) or S 117 – details in the guide “Which silicone for natural stone?”.
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