DAPCO™ 18-4F is a two-component, solvent free, thixotropic silicone paste. DAPCO™ 18-4F is most commonly used as a coating, sealant, or filleting material in the construction, repair and maintenance of all types of aircraft. The product can be applied using a variety of methods and is especially useful where fire resistance, exposure to phosphate ester fluids, and/or exposure to extreme temperatures -65 ºF (-54 ºC) to 400 ºF (204 ºC) are major considerations.

The product is Available in a variety of kit sizes including: 1/4 pint (200 grams), pints, quarts, gallons, and 55 gallon drums. (Contact your local representative for special packaging requests.)
Unit of Measure


Extreme Temperature

N/A -54 to 204 ºC-65 to 400 ºF

Typical Properties

Part A Color

N/A Dark Green

Part B Color

N/A Blue

Mixed Color

N/A Dark Green

Part A Solids

N/A 100 %

Part B Solids

N/A 100 %

Mixed Solids

N/A 100 %

Part A Consistency

N/A Thixotropic Paste

Part B Consistency

N/A Viscous Liquid

Mixed Consistency

N/A Thixotropic Paste

Part A Density

N/A 12.5 lb/gal

Part B Density

N/A 9.0 lb/gal

Mixed Density

N/A 12.2 lb/gal

Part A Shelf Life at 77 Degree Fahrenheit (ºF) Temperature

N/A 12 months

Part B Shelf Life at 77 Degree Fahrenheit (ºF) Temperature

N/A 12 months


Mixing (Handling)

N/A Part A and B must be mixed in the correct ratio and mixed thoroughly.

Recommended Mix Ratio by Weight (Part A/Part B)

N/A 100/7

Recommended Mix Ratio by Volume (Part A/Part B)

N/A 11.7/1

Working Life

N/A The working life of the mixture is 4 hours at 72 ºF (22 ºC) after mixing. Useable life can be extended by packaging the mixed product into plastic cartridges and then freezing immediately. Product can be mixed and frozen at or below 40 ± 5 ºF for 28 days. If this practice is followed, the frozen cartridges should be thawed uniformly prior to using.



N/A When using mechanical methods, care must be taken to avoid high shear equipment that may destroy thixotropy.


N/A The substrate must be free from contamination, i.e. dirt, oil grease, etc. Clean the surface by wiping with a suitable solvent/cleaning agent and dry thoroughly. Apply DAPCO™ 1-100 primer and then DAPCO™ 18-4F sealant (Note: DAPCO™ 18-4F must be applied within 90 minutes after the primer has dried). When circumstances prevent immediate application of DAPCO™ 18-4F, the surface must be cleaned thoroughly to remove the primer before repeating the entire process. Handling strength is achieved in 24 hours at 72 ºF(25 ºC) (loads on the product should be limited until full cure is achieved).


N/A DAPCO™ 18-4F is generally cured at ambient temperatures above 55 ºF (13 ºC). Cure can be accelerated by warming to 150 ºF (65 ºC) for a minimum of 4 hours. Moisture helps develop final properties (a relative humidity ranging between 30-70% is preferred). Optimum physical properties are developed when the product is cured a minimum of seven days at 72 ºF (22 ºC) and 50% R.H.

Cure may be inhibited by proximity or contact with a variety of materials including old RTV silicone sealant of the tin-cure variety, polysulfide, sulfur, amine and amide compounds, natural, nitrile or other organic rubbers, paper masking tape, plasticizers, lubricants, release agents or solvents.


N/A Before the material has cured, the excess may be removed using DAPCO™ 2000 diluent.

Typical Cured Properties


N/A 50 Shore "A"

Initial Lap Shear Strength

N/A 200 psi

Initial Lap Shear Strength after 7 Days Aging at 400 Degree Fahrenheit (ºF) (204 Degree Celsius (ºC)) Temperature

N/A 220 psi

Initial Lap Shear Strength after 7 Days Exposure to Condensing Humidity at 120 Degree Fahrenheit (ºF) (48 Degree Celsius (ºC)) Temperature

N/A 250 psi

Initial Lap Shear Strength after 7 Days Immersion in BMS 3-11 Hydraulic Fluid

N/A 220 psi

Specific Gravity

N/A 1.47

Flame Resistance BMS 5-63 Rev. J

N/A 0 Flame Penetration

Compression Set 72 Hours (hr) at 350 Degree Fahrenheit (ºF) Temperature

N/A ~55 %

Storage and Handling

Storage and Handling

N/A Store at or below 77 ºF (25 ºC)
Keep containers tightly sealed.



N/A Material Safety Data Sheet available upon request


Features and Benefits

  • Qualified to Boeing BMS 5-63
  • Compatible with DAPCO™ 2100
  • Lead-free
  • Good adhesion to a variety of substrates when primed with DAPCO™ 1-100
  • Excellent fire retardency
  • Weather ability
  • Performance at low operating temperatures
  • Good resistance to chemicals commonly used in aerospace applications
  • Repairability



N/A The information and statements herein are we believe to be reliable but are not to be construed as a warranty or representation for which Cytec Engineered Materials assumes legal responsibility. Users should undertake sufficient verification and testing to determine the suitability for their own particular purpose of any information or products referred to herein. No Warranty of Fitness for a Particular Purpose is Made. Nothing herein is to be taken as permission, inducement or recommendation to practice any patent invention without a license.