Aid in Brazing and Heat Treating Operations by Preventing Unwanted Filler Metal Flow and the Accidental Fusing Together of Parts
Nicrobraz® Stop-Off™ materials were developed by Wall Colmonoy following the invention of Nicrobraz®, the nickel-based filler metal used in hydrogen atmosphere furnace, also pioneered by Wall Colmonoy.
Nicrobraz® Stop-Off™ materials are designed to protect metal surfaces from the flow of molten brazing filler metal, or to prevent metal surfaces from adhering to each other in furnace brazing operations. Nicrobraz® Stop-Off™ materials are used successfully in brazing, in controlled-atmosphere furnaces, with flux and torches, and in molten-salt dip brazing of aluminum.
The various Nicrobraz® Stop-Off™ materials differ in composition, type, and, to some extent, purpose. It should be noted that all Stop-Off™ materials are extremely effective and should not be allowed to find their way into joints which are to be brazed. Should this happen, brazing will not occur.
We are often asked which Nicrocraft® Stop-Off™ product best fits their application. Most likely, all of them work, but some may be more suitable than others.
Below are some tips on selecting Stop-Off™ or you can download the technical bulletin here.
Act as parting compounds, designed to prevent mating surfaces from being brazed together. They effectively prevent the flow of filler metal into unwanted areas.
Acting as a parting compound to prevent accidental brazing of touching surfaces during furnace brazing, Nicrobraz® White Stop-Off™ can be applied by brushing, dipping, spraying, or with a syringe to small areas. After brazing, the remaining Stop-Off™ material can be easily brushed or wiped away.
| Forms | Container Sizes | Manufactured In |
| Type I (solvent base) | 1 kg | USA |
| 1 L | UK | |
| Type II (water base) | 1.5 kg and 40 g cartridges | USA |
| 1 L | UK | |
| Powder (used alone or with Nicrobraz® Cement) | 1 kg and 25 kg | USA |
| 1 kg | UK |
Nicrobraz® White Stop-Off™ brushed onto bracket
Nicrobraz® Red Stop-Off™, originally designed for a NASA application, is 100% chemically soluble. This assures complete removal of any remaining residue in small internal holes, fine threads, or wire screens, and similar delicate details where all traces of Stop-Off™ material must be removed following brazing.
| Forms | Container Sizes | Manufactured In |
| Type II (water base) | 1 kg and 60 g cartridges | USA |
| 1 L | UK |
Nicrobraz® Red Stop-Off™ applied to small holes on an ultra-cell
Nicrobraz® Blue Stop-Off™ is formulated to work with reactive base metals, such as titanium and zirconium, and on super alloys, in extremely high temperature and ultra-high vacuum furnace atmosphere.
| Forms | Container Sizes | Manufactured In |
| Type II (water base) | 1 kg | USA |
| 1 L | UK |
Nicrobraz® Red Stop-Off™ brushed onto surface part
Surface-active materials that prevent high temperature molten filler metal from bonding to a protected surface, either by penetration or, by flowing under the Stop-Off™.
Nicrobraz® Green Stop-Off™ is the strongest of all. It works with almost any type of base metal – except reactive metals, i.e. Ti, Zr. It can be used with any brazing method. It is the finest surface-protection agent and provides the best assurance for protecting a metal surface from a filler metal. Besides traditional liquid form, it also has the easiest-to-use PEN form. A little hard to remove but assures protection.
| Forms | Container Sizes | Manufactured In |
| Type I (solvent base) | 1 kg and 3 kg | USA |
| 1 L | UK | |
| Type II (water base) |
1 kg, 5 kg, and 200 kg | USA |
| 1 L and 10 L | UK | |
| Type II (cream) | 1 kg | UK |
| Felt-tip pen | 10 ml (12 in a box) | USA |
| Thinner | 1 L | UK |
Nicrobraz® Green Stop-Off™ Type II water base 5 kg bottle and 10 ml felt-tip pens (12 in a box)
Nicrobraz® Yellow Stop-Off™ can be used not only for furnace brazing, but also for open-air torch brazing. This is typically used along side Nicrobraz® LM Rod. When a heavy layer of flux is being used, apply Nicrobraz® Yellow Stop-Off™ as much as possible.
| Forms | Container Sizes | Manufactured In |
| Type II (water base) | 1.5 kg | USA |
| 1 L | UK |
Nicrobraz® Yellow Stop-Off™ for torch brazing
Nicrobraz® Orange Stop-Off™, as well as Blue Stop-Off™, work effectively as a high-temperature lubricant and prevent damage to surfaces in contact and subject to movement in super-plastic forming operation.
| Forms | Container Sizes | Manufactured In |
| Type I (solvent base) | 1 kg and 3 kg | USA |
| 1 L | UK |
Nicrobraz® Orange Stop-Off™ brushed on vane segment
Type I
The solvent-based Type I materials are flammable, and should be handled as such. Normal caution should be exercised in their use. They should only be used in well-ventilated areas. Use if there is a chance of oil on the surface from the shop air. Type I is much thinner than Type II. Generally has a better bond to the base metal surface after application.
Type II
The water-based Type II products may be preferable, since they have no objectionable smell and are not flammable. (Read the material safety data sheet, before use, for further instructions on using and storing these materials.) Make sure the surfaces are clean and oil free.
The minimum shelf life is 24 months for Nicrobraz® Stop-Off™ Type I and Type II products. To prolong storage life, this product should be kept in a tightly sealed container away from any heat sources, in a cool area. Download Tech Bulletin here.
