primer for sanded galvanised steel?

[mike k]

I purchased a small stand mounted spray booth which I plan on using for some powder coating. As the booth was used it was in need of a refurbished to prevent any contamination issues as it was previously used for coating but not well kept. The booth is made from galvanised steel with the stand and outside of the booth being brush painted (visible surfaces) which wasn't the best as no prep was evident before painting. The inside of the booth was contaminated with an unknown powder from what was being coated which took some serious sanding to remove, so basically the floor of the booth is back to bare untreated steel, the paint on the outer of to the booth I sanded back to bare untreated steel. I bought some rattle can aldi metal paint - gloss white for the inside of the booth and Red for the outer. As I have removed the galvanised zinc from the steel is it advisable to use a primer or do I just spray the metal paint straight onto the prepped steel?

Many thanks

mike

 

[the snooper]

are you sure you have removed all of the galv ?

if not you will need acid etch or mordant solution

 

[mike k]

On the base panel of the booth I'm back to shiney bare steel (the inside of the booth was unpainted but the base panel was heavily contaminated), the rest which was painted I couldn't be sure as the brush paint wasn't bonded too well but I was using a belt sander with 60 grit so I would say so to be safe. The inside of the sheet metal was unpainted so still galvanised if that helps.....

 

[the snooper]

galv will look like shiny bare steel when sanded and I would be surprised if a belt sander would remove it your best option is to give a light coat of acid etch followed by some primer then what ever top coat you want to use

 

[anjum]

Lrchler epoxy will go on to galvanised steel see http://www.paints4u.com/pdffiles/29107.pdf

 

[mike k]

galv will look like shiny bare steel when sanded and I would be surprised if a belt sander would remove it your best option is to give a light coat of acid etch followed by some primer then what ever top coat you want to use

Thanks for the info, the acid etch is to give the further coats something to adhere too?

learnt that the hard way once after the local paint shop told me I didn't need it when I put a bonnet back to bare metal!

The reason I made the original post was the rattle can metal protection from aldi says no need for primer so wasn't sure the best route to take. I just want a practical durable finish as the previous brush paint was easy to flake off in some parts.

Lrchler epoxy will go on to galvanised steel see http://www.paints4u.com/pdffiles/29107.pdf

Thanks for the link, I'm looking for something in a rattle can as I don't have an air fed mask, just a body line spray mask which I have used for spraying 2k primer and I had tickle lungs for a few weeks after - and that was spraying outside!

 

[richie00boy]

If it must be a rattle can take a look at U-pol Acid #8.

As a side note, epoxy primer doesn't contain isocyanates, but the fact that you had bad lungs after spraying with your Bodyline mask would suggest the mask is not suited to spraying epoxy either, as that also has hazardous/sensitising components. Possibly it was just a dust mask, which I wouldn't even say was suitable for any kind of spraying really.

 

[mike k]

If it must be a rattle can take a look at U-pol Acid #8.

As a side note, epoxy primer doesn't contain isocyanates, but the fact that you had bad lungs after spraying with your Bodyline mask would suggest the mask is not suited to spraying epoxy either, as that also has hazardous/sensitising components. Possibly it was just a dust mask, which I wouldn't even say was suitable for any kind of spraying really.

Thanks for the recommendation, I actually sprayed one panel after prepping with the metal protect spray paint as a test panel then I'll check it tomorrow after its hardened. The booth had no rust on it, even the unpainted panels so I'm thinking it should be okay as it would cost a small fortune in rattle cans to use acid etch primer, at least 10 cans so be a ton just in primer. The mask has gas cartridges and I've just checked as I've just ordered some new ones. The bad lungs may have come from all the sanding as I used to be a bit stupid and not always have it on. I'm a bit older and wiser now but still gonna stay away from 2k. Is there a safer alternative to 2k that I can use in my spray gun for painting on top of the metal protect paint as cans are very tedious and I want the outer of the booth in red?

 

[anjum]

If you don't mind the finish you can brush the epoxy on. It doesn't contain isocyanates but best to be careful. Rattle cans aren't much better.
Might be best to brush paint on anyway

 

[richie00boy]

You could use cellulose in your gun as that would be no worse, probably actually better, than the spraycan you are putting on. But it would need primer. You can get Acid #8 in a tin for a gun though, and it's ready to spray.

You would probably be better taking off the spraycan paint though, especially if it's recent, as it will probably react. If you wanted to chance it, it will certainly need flatting down to key, regardless of what you put on top of it.

 

[eil]

If it must be a rattle can take a look at U-pol Acid #8.

As a side note, epoxy primer doesn't contain isocyanates, but the fact that you had bad lungs after spraying with your Bodyline mask would suggest the mask is not suited to spraying epoxy either, as that also has hazardous/sensitising components. Possibly it was just a dust mask, which I wouldn't even say was suitable for any kind of spraying really.

We need to be careful about saying that epoxy primer doesn't contain isocyanate's as some do and some don't, best to check first before spraying. No problem if you roll or brush it on though, but I would still wear a good mask as the fumes it gives off is pretty potent.

 

[richie00boy]

I have not found any that does contain isocyanates and iso technology is usually used with polyurethane, if you know of a product it would be good to know.

However, I think epoxy is just as bad as iso, they both have sensitising effect. It just affects the nervous (hormone) system rather than respiratory. So I would use the same (high performance) mask when using either iso or epoxy. Iso is much more widely used so has had more attention by the HSE, who knows in a few years time maybe they will be saying to use epoxy only with an air fed mask.

The slight thing making epoxy potentially less dangerous is that it tends to be applied with less atomisation, so the cloud is less severe.

 

[mike k]

Thanks for the input, especially regarding safety.

I have had paint react before when putting cellulose over 2k. I decided to get more of the cheap rattle cans from aldi, does take a few coats too get coverage but looks good for rattle cans - feels almost like powder coat. Certainly not like car paint in cans I have used in the past. As the metal protect cans are such good value I have fetched enough to use as a primer on the outside of the booth panels and some cheap red cans

https://www.aldi.co.uk/en/specialbuys/sunday-9th-february/product-detail/ps/p/colour-spray-paint/

will I have any problems spraying this over the metal protect paint, or any other advice is much appreciated.

Mike

 

[richie00boy]

The direct to metal paints are often a kind of enamel and tend to react when overcoated. Why do you want to cover it if the finish is reasonable as you say? Your first post gave me the impression that you had the right colours.

 

[mike k]

The direct to metal paints are often a kind of enamel and tend to react when overcoated. Why do you want to cover it if the finish is reasonable as you say? Your first post gave me the impression that you had the right colours.

the interior of the booth I want gloss white for better illumination. As the metal protect is good value and a third of the price of acid etch primer I have bought a load of the white to use as a primer for the outside of the panels but don't want a white finish, they don't do the metal protect in red so I gave bought some cheap colour paint (in the link I posted in my previous post) just for aesthetics - if that makes sense? Just want to know if the two will react.........