Weirdness with silicone plugs

[UrineMachine]

Hey all,

I recently bought the big caswell silicone plug kit and had the opportunity to use them on a part. Well, the part was a extruded aluminum fuel rail. I plugged the fuel injector bosses up with appropriately sized silicone plugs and went at it with "anodize red" powder. The color came out great, but there was some weird anomaly around the silicone plugs. I guess I didn't notice when first applying the powder but the around about 1/8" around the plug had some weird texture to it that was not in the metal - almost like the silicone plug was screwing with the way the powder adhered. Very weird.

I then thought maybe it was because the part was clear anodized and it created some weird effect, though the rest of the rail was absolutely fine, just where the plugs went was weird. So I did another part with plugs this time it was a billet aluminum oil filter lid with ports for fittings for an oil cooler. Again I needed to use the plugs. Stock them in, applied powder (this time wrinkle black) and... weird effected area around the plugs! This time it was for a customer and I couldn't have anything but perfection, so I took the plugs out and cut them with a razer so they were sunk in below the face of the material (I probably could have just masked the holes at this point!) and the powder went down normalish and looked fine afterward.


What the hell is wrong with using plugs? Why am I getting this result?

Thanks guys!

[jtagger19]

I always remove plugs before placing the part in the oven.
powder over builds around the plugs

[UrineMachine]

Thats good advice but thats not the problem - the problem is the weird "field" around the plug when applying powder!

[Harleydad]

Faraday Cage effect, just like inside corners. That texture you saw was most likely not enough powder.

[baz]

2 things i had with those

1 faraday effect like harleydad said
2 a couple of times i cleaned the parts after putting the plugs in .
maybe it was not evaporating around the plugs but it left a finish like if
something was contaminated 1/8 all aroubd the plugs
now i clean before i put the plugs in

[PCT17522]

"a couple of times i cleaned the parts after putting the plugs in .
maybe it was not evaporating around the plugs but it left a finish like if
something was contaminated 1/8 all aroubd the plugs
now i clean before i put the plugs in"

I've noticed something similar to this. When I noticed it, it was in machined holes and I just didn't (or couldn't through normal means) clean them well enough. When I sprayed the parts (or, more acurately,after I sprayed them and before i put them in the oven to cure) the powder began to "wick" the leftover machining lubricant (or un-evaporated cleaning agent) out of the holes around the plugs. Now I always try to bake the part first to allow any leftover residue to burn up or evaporate ahead of time, then re-clean and/or blast.

[UrineMachine]

Originally Posted by PCT17522

"a couple of times i cleaned the parts after putting the plugs in .
maybe it was not evaporating around the plugs but it left a finish like if
something was contaminated 1/8 all aroubd the plugs
now i clean before i put the plugs in"

I've noticed something similar to this. When I noticed it, it was in machined holes and I just didn't (or couldn't through normal means) clean them well enough. When I sprayed the parts (or, more acurately,after I sprayed them and before i put them in the oven to cure) the powder began to "wick" the leftover machining lubricant (or un-evaporated cleaning agent) out of the holes around the plugs. Now I always try to bake the part first to allow any leftover residue to burn up or evaporate ahead of time, then re-clean and/or blast.

Sorry I should have clarified. The part was bead blasted and then sprayed with acetone and let dry for 20 mins and sprayed with compressed air. What I meant by "cleaned off" wass that the powder would lay weird and I'd blow it/clean it off, and it'd do it again.