Bilt Hamber Dynax-S50 is the cavity wax of the Dynax range: it creeps deep into seams, box sections and sills, displaces moisture and stays soft and self-healing. That gives the strongest corrosion protection of the three Dynax waxes, exactly on the spots you cannot see. You apply it with the injection lance and let the cavities off-gas afterwards. You will find the Bilt Hamber Dynax-S50 in the shop.
What Dynax-S50 does
Dynax-S50 is made for the hidden cavities where cars rust from the inside out: box sections, sills, doors and moisture traps. Bilt Hamber states that S50 has the strongest anti-corrosion power of the range, but deliberately dries soft to a translucent, brown, self-healing wax film. That soft, mobile character is exactly why it creeps into seams so well and heals itself after damage. In the ASTM B117 salt-spray test it outperforms competing cavity waxes; the University of Hertfordshire School of Engineering named it best cavity wax.
How to use it
Prepare. Work on a clean, degreased surface. S50 displaces moisture, so lightly damp is fine; treat very wet cavities first with Bilt Hamber Ferrosol.
Apply. From the aerosol use the supplied 600mm injection lance for a fine 360-degree mist inside the cavity; from the 5L container apply it with spray equipment, a brush or a roller.
Let it off-gas. Leave the cavities open for around 48 hours so the solvents can escape; aim for a dry film thickness of about 50 microns.
Check and touch up. Check hard-to-reach spots and re-spray where needed.
Soft, self-healing and what to watch for
S50 stays deliberately soft: ideal in enclosed cavities, but less suited to the exposed underside where stone chips and abrasion take their toll. For that visibly exposed underbody you choose the firmer Bilt Hamber Dynax-UB; for visible areas that must stay transparent the Bilt Hamber Dynax-UC. In cold weather S50 thickens; let it reach room temperature for a day. Clean up with white spirit. The full approach is in the guide rust prevention and underbody protection.