Willster, a valid diagnosis is nearly impossible without specific information on each and every case. All I can do is give you some general concepts which may help you identify the problem yourself.
Whether the RCF will spread or bead up on a Vinyl surface depends both on the RCF and the Vinyl surface (not the vinyl). The contact angle between the RCF droplet and the surface must be favorable for the liquid droplet to spread. Part of the requirement is for the surface tension of the RCF to be low, the lower the better (pure water has a surface tension of about 60-70 dyne/cm; good surfactants will reduce the surface tension by a factor of three, to around 20 dyne/cm). The other parameter is the wettability of the Vinyl surface.
With different RCFs, you may have different surface tensions which lead to different spreading tendencies. With the same RCF, the surface tension will tend to increase if the RCF is diluted with too much water.
The vinyl itself is pretty much an invariant. The polymer molecular structure is ALWAYS the same, a polyvinylchloride or (—CH2—CHCl—)n. The amount of plasticizer (phthalate ester or 1,2 benzenedicarboxylate) used to soften the vinyl may vary slightly from record to record but this is unlikely to fundamentally change the wettability of the Vinyl surface. The type or amount of mold release (Teflon or silicone product) covering the Vinyl surface is also likely to vary from record to record. This will alter the wettability of the Vinyl surface.
So in a nutshell, either the surface tension varies with different brands of RCF and different levels of dilution or the wettability of the Vinyl surface varies with different types or amounts of mold release. The important thing is you can’t clean what you can’t touch: if your RCF does not completely wet the Vinyl surface, you cannot clean it well. Apply the full-strength RCF a couple of times to ensure intimate contact for better results.
Whether the RCF will spread or bead up on a Vinyl surface depends both on the RCF and the Vinyl surface (not the vinyl). The contact angle between the RCF droplet and the surface must be favorable for the liquid droplet to spread. Part of the requirement is for the surface tension of the RCF to be low, the lower the better (pure water has a surface tension of about 60-70 dyne/cm; good surfactants will reduce the surface tension by a factor of three, to around 20 dyne/cm). The other parameter is the wettability of the Vinyl surface.
With different RCFs, you may have different surface tensions which lead to different spreading tendencies. With the same RCF, the surface tension will tend to increase if the RCF is diluted with too much water.
The vinyl itself is pretty much an invariant. The polymer molecular structure is ALWAYS the same, a polyvinylchloride or (—CH2—CHCl—)n. The amount of plasticizer (phthalate ester or 1,2 benzenedicarboxylate) used to soften the vinyl may vary slightly from record to record but this is unlikely to fundamentally change the wettability of the Vinyl surface. The type or amount of mold release (Teflon or silicone product) covering the Vinyl surface is also likely to vary from record to record. This will alter the wettability of the Vinyl surface.
So in a nutshell, either the surface tension varies with different brands of RCF and different levels of dilution or the wettability of the Vinyl surface varies with different types or amounts of mold release. The important thing is you can’t clean what you can’t touch: if your RCF does not completely wet the Vinyl surface, you cannot clean it well. Apply the full-strength RCF a couple of times to ensure intimate contact for better results.