Painting
Hi Henrik,
Painting is a good solution if you cannot get anodising done. You will have to use 'matt black enamel paint'. Thickness should be as low as possible without the danger of the paint stripping off. I would also avoid any primer as it is an additional layer.
Enamel paint generally sticks pretty well on any clean aluminum surface. I generally wash the aluminum with dishwashing soap that really strips off all the grease ( Very important). The liquid ones are best at this. I soak it for 15 minutes and then brush the surface with soapy water before the final wash.
The matt black surface provides a much larger surface area than shiny paint. This is not to be confused with normal surface area. The matt finish improves the efficiency of the heat sink.
Spraying is a good idea but brushing is also easy . Enamel paint spreads easily and takes time to dry, so you will not get any brush marks.
The painting process for me is always messy and smelly. Do it in the garage or outside the house. Matt black enamel gets around very easily. You can avoid all this with NC matt black ( nitrocellulose paint - car paint). I never found this to stick to aluminum easily without a primer. Check out with your supplier. You may get better paint at your hardware dealer.
Have fun.
Cheers.
Hi Henrik,
Painting is a good solution if you cannot get anodising done. You will have to use 'matt black enamel paint'. Thickness should be as low as possible without the danger of the paint stripping off. I would also avoid any primer as it is an additional layer.
Enamel paint generally sticks pretty well on any clean aluminum surface. I generally wash the aluminum with dishwashing soap that really strips off all the grease ( Very important). The liquid ones are best at this. I soak it for 15 minutes and then brush the surface with soapy water before the final wash.
The matt black surface provides a much larger surface area than shiny paint. This is not to be confused with normal surface area. The matt finish improves the efficiency of the heat sink.
Spraying is a good idea but brushing is also easy . Enamel paint spreads easily and takes time to dry, so you will not get any brush marks.
The painting process for me is always messy and smelly. Do it in the garage or outside the house. Matt black enamel gets around very easily. You can avoid all this with NC matt black ( nitrocellulose paint - car paint). I never found this to stick to aluminum easily without a primer. Check out with your supplier. You may get better paint at your hardware dealer.
Have fun.
Cheers.
If the heatsinks are raw aluminum then you need to do something to them. I strongly suggest looking in your local yellow pages (phone book) for companies that do metal finishing, extruding or plating (try motorcyle shops). You could most likely get the heatsinks anodized for a modest amount of money. Especially if you can wait for them to run with another set of items and are not particular about the color.
If the heatsinks are already anodied and you just don't like the color (clear or yellow) I hope you realise that painting them black will make them less effective heat sinks, not more effective. Paint is an insulator and will act like a blanket to slow the heat being conducted to the air.
The major mechanism involved in how a heatsink transfer heat to the air is through conduction. The air molecules that are in contact with the heat sink get hot, hot air rises so they are replaced with cooler air and the process repeats. Some heat is dissipated via radiation which is improved by dark colors, but this is a small percentage of the total energy transferred.
To give you a real world example, turn a burner on your electric stove on high and wait for the element to start visibly glowing. Hold a piece of paper near the element. It will get hot, but not a lot will happen to it. Touch the paper to the element, it will quickly brown and if left in contact very long will most likely catch fire. That is the difference in efficiency between conduction and radiation.
The main positive effect of adding a cooling fan to a heatsink is that it improves conduction. How the air moves through the heat sink is more important than how much air is moving. When done right a fan creates turbulant air flow which brings cooler air in contact with the heat sink. This is why it is better to push air onto a heatsink rather than pulling air through the heatsink.
Phil
If the heatsinks are already anodied and you just don't like the color (clear or yellow) I hope you realise that painting them black will make them less effective heat sinks, not more effective. Paint is an insulator and will act like a blanket to slow the heat being conducted to the air.
The major mechanism involved in how a heatsink transfer heat to the air is through conduction. The air molecules that are in contact with the heat sink get hot, hot air rises so they are replaced with cooler air and the process repeats. Some heat is dissipated via radiation which is improved by dark colors, but this is a small percentage of the total energy transferred.
To give you a real world example, turn a burner on your electric stove on high and wait for the element to start visibly glowing. Hold a piece of paper near the element. It will get hot, but not a lot will happen to it. Touch the paper to the element, it will quickly brown and if left in contact very long will most likely catch fire. That is the difference in efficiency between conduction and radiation.
The main positive effect of adding a cooling fan to a heatsink is that it improves conduction. How the air moves through the heat sink is more important than how much air is moving. When done right a fan creates turbulant air flow which brings cooler air in contact with the heat sink. This is why it is better to push air onto a heatsink rather than pulling air through the heatsink.
Phil
A friend of mine suggested that I should get the heatsinks glass-blown ( translated directly from danish 
) and the cover them with a thin layer of clear lacquer. Think that could look awesome.
Again I don't think the heat is going to cause trouble. With 1 meter and 22 kg of heatsink per channel I'm more nervous about it's going to be to cold. Time will tell
) and the cover them with a thin layer of clear lacquer. Think that could look awesome.Again I don't think the heat is going to cause trouble. With 1 meter and 22 kg of heatsink per channel I'm more nervous about it's going to be to cold. Time will tell
Do you mean sand-blasted? Kind of like a mad attempt ant rubbing the things down with a 'liquid-like' sand paper so it can get into all of the cornenrs easily. I f that is what you mean then that probably would look good and you may not even need to put any lacquer on htem as the aluminium will not corode even if left bare.
HenrikKronborg,
There is a thing called bead-blasting. it uses very small glass beads to strip finishes and it also work-hardens the surface to make it resistant to abrasion. Blasting can be anything from silicon carbide (definitely not recommended for Al) to walnut shells and just about everything in between. It all depends on what finish you want. I have even used salt, which is nice because what you don't get cleaned up disolves with the next rain.
I have a couple of recommendations for you:
1) painting can be a real pain especially if you fins are deep and close together. You can end up wth a pretty poor finish because you cant get down into the fins evenly.
2) there are some alternatives out there like gun-blueing. Some brands will work on aluminum as well as steel. It doesn't come out as even as anodizing and takes a little practice to get it right. Just don't get it on your hands.
3) there are some liquid spray on oil-wax based chemicals that dry on and are designed for bare metals. One is Boeshield T-9. You spray it on, wipe it evenly and let it dry. it prevents corrosion, fingerprints and dust doesn't stick to it. Neat stuff.
4) my best recommendation is really anodizing. The best places to check for a service is paintball stores and game fields. Those guys are really into it and quite a few do it at home. Soemone might hook you up for a small fee. Other places are model hobby stores, aircraft repair shops and custom car shops (mostly the guys that do lowered imports with big wings). Ask them and see if there is a guy who does out of his workshop.
There is a thing called bead-blasting. it uses very small glass beads to strip finishes and it also work-hardens the surface to make it resistant to abrasion. Blasting can be anything from silicon carbide (definitely not recommended for Al) to walnut shells and just about everything in between. It all depends on what finish you want. I have even used salt, which is nice because what you don't get cleaned up disolves with the next rain.
I have a couple of recommendations for you:
1) painting can be a real pain especially if you fins are deep and close together. You can end up wth a pretty poor finish because you cant get down into the fins evenly.
2) there are some alternatives out there like gun-blueing. Some brands will work on aluminum as well as steel. It doesn't come out as even as anodizing and takes a little practice to get it right. Just don't get it on your hands.
3) there are some liquid spray on oil-wax based chemicals that dry on and are designed for bare metals. One is Boeshield T-9. You spray it on, wipe it evenly and let it dry. it prevents corrosion, fingerprints and dust doesn't stick to it. Neat stuff.
4) my best recommendation is really anodizing. The best places to check for a service is paintball stores and game fields. Those guys are really into it and quite a few do it at home. Soemone might hook you up for a small fee. Other places are model hobby stores, aircraft repair shops and custom car shops (mostly the guys that do lowered imports with big wings). Ask them and see if there is a guy who does out of his workshop.
Re: Sand-blasted
Glass bead blasting, yes,
That is what I had done to some front panels. Great look, scratch resistant and doesn't attract dirt. Defenitely recommended for looks. But make sure the guy realises it needs to be done with rather fine beads. The stuff they use to blast bridges wouldn't look as good....
Jan Didden
HenrikKronborg said:bigparsnip,
just the word I was looking for
/Henrik
Glass bead blasting, yes,
That is what I had done to some front panels. Great look, scratch resistant and doesn't attract dirt. Defenitely recommended for looks. But make sure the guy realises it needs to be done with rather fine beads. The stuff they use to blast bridges wouldn't look as good....
Jan Didden
Good solution for quick protection of aluminum is alodine. Search the forum, there is some info on that. The only color available is gold, but it can be done relatively cheap and fast at home. I sometimes use this method, if I don't have enough time to wait for anodizing (usually a week turn around). Just dip it in a liquid and rinse in water.
Doing anodizing at home is not practical, unless it's part of your business. Although the link was very interesting. Bare aluminum, doesn't really corrode, if not exposed to elements (like outside use). I have some units, I didn't protect at all (just brushing) and they are still in perfect shape after 20 years. If you brush them in a certain way (like using wet sandaper), they don't even show much fingermarks.
Philo,
Where that Boeshield T-9 can be obtained from?
Doing anodizing at home is not practical, unless it's part of your business. Although the link was very interesting. Bare aluminum, doesn't really corrode, if not exposed to elements (like outside use). I have some units, I didn't protect at all (just brushing) and they are still in perfect shape after 20 years. If you brush them in a certain way (like using wet sandaper), they don't even show much fingermarks.
Philo,
Where that Boeshield T-9 can be obtained from?
Peter,
I bought it from Rockler Woodworking but I have seen it at other woodworking and tool stores. It cam as part of a three part system to clean router bits and saw blades of pitch and the T-9 reduces friction and buildup. You can buyjust the protecterant through some chemical and cleaning supply houses in sizes up to a gallon. I also use it on my Harley and my mountainbike. I like it alot, as you can probably tellBoeshield
I bought it from Rockler Woodworking but I have seen it at other woodworking and tool stores. It cam as part of a three part system to clean router bits and saw blades of pitch and the T-9 reduces friction and buildup. You can buyjust the protecterant through some chemical and cleaning supply houses in sizes up to a gallon. I also use it on my Harley and my mountainbike. I like it alot, as you can probably tell
Boeshield
I'm sorry that I need to not approve with you peter.
Alodine is not only gold.
Alodine 1201, 1201, 600 & irrite (all commercial name, the technical name is chemical surface conversion) is gold and it used for corrosion protection and to improve paint adhesion.
Alodine 1000 is primary used for electrical bonding application. and is colour is mostly colorless. this type have less corrosion resistance then alodine 1200 but still better than nothing.
Aluminium can corrode VERY quickly...it all depend of the alloys and the environment. (I work as a quality inspector for Wing Skin and I see lot of corrosion and the part is not made for century =))
Francois Gregoire
Alodine is not only gold.
Alodine 1201, 1201, 600 & irrite (all commercial name, the technical name is chemical surface conversion) is gold and it used for corrosion protection and to improve paint adhesion.
Alodine 1000 is primary used for electrical bonding application. and is colour is mostly colorless. this type have less corrosion resistance then alodine 1200 but still better than nothing.
Aluminium can corrode VERY quickly...it all depend of the alloys and the environment. (I work as a quality inspector for Wing Skin and I see lot of corrosion and the part is not made for century =))
Francois Gregoire
Dark Shadow said:
While you are right on the point that alodine used for electrical bonding application is colorless, yet it's use for protecting or finishing chassiss or heatsinks is questionable, and the only finish that I think is of any use, is still gold.
Again, you are right that exposed aluminum corrodes quickly, especially when used on aircrafts
, but in home environment it's really rare. I have equipment that I built 20 years ago and I don't see slightest sign of corrosion. Even the aluminum stock, I keep in garage, is corrosion free for years.BTW, I went through 4 days of qualification training at Bombardier, in Montreal last summer. One whole day was spend on alodine applications, types and usage. The test at the end of that day had the lowest marks during all 4 days
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.