Ano
Service
Chem film, clear and gold.
Chemical conversion coating to MIL-DTL-5541 in clear and gold, Class 1A and Class 3, for corrosion protection that keeps the part conductive.
Plain English first
What is chem film?
Chem film, also called chemical conversion coating, chromate, or by the trade name Alodine, is a thin conversion layer that protects aluminum from corrosion while keeping the surface electrically conductive. That combination is why avionics housings, ground planes, and anything that needs bonding or EMI shielding gets a 5541 callout instead of anodize. It is also the standard base under paint systems.
Classes and types
Reading the 5541 callout.
| CALLOUT | MEANS | PICK IT WHEN |
|---|---|---|
| Class 1A | Maximum corrosion protection | The part faces weather or salt |
| Class 3 | Thinner, low-resistance coat | Grounding and bonding lead |
| Type I | Traditional hexavalent chemistry | The print says so |
| Type II | Trivalent alternative | The print or policy says so |
We run clear and gold to the callout on your print.
Chem film or anodize
Two different jobs.
Anodize builds a hard insulating oxide; chem film stays thin and conductive. When the print needs wear resistance, that is hard coat territory. When it needs grounding, bonding, or a paint base, that is 5541. Some assemblies need both on different surfaces, which is where masking comes in. The controlling document is MIL-DTL-5541 on the government spec library at quicksearch.dla.mil. We also support PRC-5005 work.
How it runs in Paoli
A 5541 job through the shop.
Read the callout together
Type, class, and color from the print. Ambiguous callouts get flagged before the run, not after.
Clean and prep
Conversion coating quality is decided in cleaning; the surface has to be genuinely bare.
Convert and finish
The chemistry converts the surface in a controlled dip. Clear or gold per the print.
Protect the conductivity path
Class 3 work is about low resistance, so the finish is handled and packed to protect it.
Questions
Common questions on this service
Is chem film conductive?
Yes, that is its defining advantage. Class 3 in particular is specified where low contact resistance matters.
Does chem film change dimensions?
The conversion layer is extremely thin, so it is dimensionally negligible for nearly all machined work.
Can you chem film and anodize the same part?
Yes, on different surfaces with masking to your print. Call out both processes on the drawing and we will run them in the right order.
Does chem film protect as well as anodize?
Different jobs. Anodize builds a thick insulating layer with wear resistance; chem film is thin, conductive, and self-healing on minor scratches. The print decides which protection the part needs.
Can chem film go under paint?
Yes, it is the standard base for paint systems on aluminum. Tell us the paint spec so the class selection matches.
5541 work, back in 3 to 4 days.
Clear or gold, Class 1A or 3, quoted from the print.