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-   -   Re-spraying record decks. (https://www.vintage-radio.net/forum/showthread.php?t=162342)

Diabolical Artificer 25th Dec 2019 3:54 pm

Re: Re-spraying record decks.
 
Joe is right, I put ali chassis's and the paint tins to the side of my open fire for 30 mins before spraying, then a quick wipe with a tack cloth.

Another tip is to make a spray booth out of a big cardboard box, this can be closed after spraying to stop hairs and other crap getting on the surface.

With spray cans spraying from the right distance (and speed) determines what sort of finish you get, it's a good idea to use a good nozzle too, the ones that spray a "flat" spray are good, clean with thinners afterwards.

Lastly always start spraying from the side, thing to be sprayed vertical, start at the bottom and move up making sure you've got good coverage; it's a good idea to do a test panel first.

Andy.

Radio Wrangler 25th Dec 2019 4:29 pm

Re: Re-spraying record decks.
 
Don't try for total opacity in one coat. Make your first coat cover everything with a uniform degree of opacity, leave it a while to flash off solvent, spray another similar layer, and keep repeating until you have full opacity. It's a common mistake to try to lay the whole lot down in one pass.

Remember that the solvents are highly inflammable and that you can reach explosive proportions before you notice...qv the recent news article on the smoker who'd used a lot of air freshener in his car before lighting up. It blew the car apart with him in it and damaged windows in nearby buildings. Good ventilation is rather important.

David

Al (astral highway) 28th Dec 2019 3:49 pm

Re: Re-spraying record decks.
 
Scimitar (post #11) and others , Iím following this with interest. If I brush or roller Lechler, do the rugosities or brush-strokes flatten out by themselves?

Herald1360 29th Dec 2019 10:47 am

Re: Re-spraying record decks.
 
Quote:

Originally Posted by astral highway (Post 1202627)

rugosities

I just learned a new word!

8-)

I wonder if the etymology has similar origins to rug as in carpet?

Al (astral highway) 29th Dec 2019 11:27 pm

Re: Re-spraying record decks.
 
1 Attachment(s)
Quote:

Originally Posted by Herald1360 (Post 1202839)
Quote:

Originally Posted by astral highway (Post 1202627)

rugosities

I just learned a new word!

8-)

Hi Chris , it’s a great-sounding word, isn’t it? I like that it can be used quite mathematically ( dealing with smoothness/roughness as a ratio, so relevant to quantifying why one isurface is more ideal / ready for painting than another- or why one finish looks better than another! )

... as well as more casually to describe variations in texture - and also in some aspects of complexity science.

Radio Wrangler 30th Dec 2019 5:47 am

Re: Re-spraying record decks.
 
So etched foil capacitors are all about achieving more capacitance through rugosity.

Useful!

I'll write it down in my vocabulary book :-)

David

Al (astral highway) 30th Dec 2019 10:01 am

Re: Re-spraying record decks.
 
Quote:

Originally Posted by Radio Wrangler (Post 1203084)
So etched foil capacitors are all about achieving more capacitance through rugosity.

yep, perfect example!

Quote:

Originally Posted by Radio Wrangler (Post 1203084)

Useful!

I'll write it down in my vocabulary book :-)

How about *rugulose*?

The more *rugulose* an etched foil anode, the greater the capacitance .... or should that be ‘the more *rugose*, yet another one starting with rug- :-)

These two are just distinguished apart by relative fine-ness or coarseness of wrinkle and don’t express things mathematically. Only rugosity has that capability.
Let’s give a big hand to the nuances of Latinate words !

Scimitar 30th Dec 2019 10:39 am

Re: Re-spraying record decks.
 
Quote:

Originally Posted by astral highway (Post 1202627)
Scimitar (post #11) and others , Iím following this with interest. If I brush or roller Lechler, do the rugosities or brush-strokes flatten out by themselves?

The technical term you are looking for is "flow out". :)

It is to do with how fast the solvents evaporate. The slower the evaporation, the better the flow out. If it dries too fast, there is not enough time for it to do so. You will see that problem with water based domestic paints.

It is unlikely that you will get a perfect surface when brushing or rollering, so expect to flat it back after curing (12 hours ish). I would use 120 grit dry before painting, then 320 grit dry followed by 500 and then 800 but finishing at 500 will do for most non metallic finishes.

Al (astral highway) 30th Dec 2019 11:30 am

Re: Re-spraying record decks.
 
Thank you , Scimitar, this is very helpful. I’ll add ‘flow-out’ to my vocab!

A few more Q’s:

1) what’s the difference between two-part epoxy primer like Lechler and two-part epoxy resin adhesive?

2) can I successfully apply two-part epoxy primer as a finishing coat over cured yacht varnish? (This is for a historic reason, not starting from scratch)

3) And, when I do want a finishing coat, what is a good brand / source of small quantities of finishing coat to brush over the cured Lechler? This is for small areas but with a high aesthetic impact. Heat resistance is ideal.

Scimitar 30th Dec 2019 12:43 pm

Re: Re-spraying record decks.
 
Quote:

Originally Posted by astral highway (Post 1203152)
Thank you , Scimitar, this is very helpful. Iíll add Ďflow-outí to my vocab!
1) whatís the difference between two-part epoxy primer like Lechler and two-part epoxy resin adhesive?

They are closely related. It is largely the amount of filler materials and pigments etc that make up the difference.

Quote:

Originally Posted by astral highway (Post 1203152)
2) can I successfully apply two-part epoxy primer as a finishing coat over cured yacht varnish? (This is for a historic reason, not starting from scratch )

You can but a) the primer is going to go chalky eventually with UV exposure and b) the whole lot will only be as good as the weakest link. In your case, the varnish. The best adhesion will result from stripping it off.

Quote:

Originally Posted by astral highway (Post 1203152)
3) And, when I do want a finishing coat, what is a good brand / source of small quantities of finishing coat to brush over the cured Lechler? This is for small areas but with a high aesthetic impact. Heat resistance is ideal .

Anything you like. The epoxy primer is inert and so aerosol car paint or anything else you choose will go on without issue. If you want it classy, I would go to a car paint supplier and get an aerosol made up of a metallic basecoat that you like and an aerosol of 1K lacquer.

Al (astral highway) 30th Dec 2019 12:50 pm

Re: Re-spraying record decks.
 
Thank you Scimitar.

On 1), since they’re closely related, can I use the primer as an adhesive in some circumstances ? The Lechler is costly and it’s ideal if I can double up .

Scimitar 30th Dec 2019 1:34 pm

Re: Re-spraying record decks.
 
No, it's too thin.

The Lechlar is about £15 per litre including the hardener when bought as a 2:1 litre. I use Express Paints in the south somewhere.

Al (astral highway) 30th Dec 2019 3:22 pm

Re: Re-spraying record decks.
 
Quote:

Originally Posted by Scimitar (Post 1203186)

The Lechlar is about £15 per litre including the hardener when bought as a 2:1 litre.

Nice, thatís very reasonable . Cheers

Argus25 31st Dec 2019 10:02 pm

Re: Re-spraying record decks.
 
It depends a lot what base metal you are dealing with.

If it is a cast aluminium like metal it can be very difficult to get the new paint to stick well without an etch prime. I use Alodine which is used in the aircraft industry to prepare aluminium part prior to painting and then, for a task like a turntable (say a Garard 301 or similar) I have used enamel spray, VHT is by far the better spray enamel because you can bake it in a domestic oven, 80 to 90 Deg C is fine. And it sticks is very well to the primer and goes rock hard and scratch resistant with a nice gloss finish that looks like a professional paint job.

If it's Steel its a whole different ball of wax because you have rust to contend with. If it is not practical to take it to the electroplaters (have all rust removed and zinc plated) I use Fertan organic rust converter. Then directly over that I would use Holts automotive spray lacquer as it sticks very well to the Fertan film on the surface. If you have a look at the small Mullard speaker in the TRF radio I made recently on another thread, it was very rusty, treated with Fertan and sprayed with Holts brown metallic lacquer to restore its finish.

Scimitar 31st Dec 2019 10:51 pm

Re: Re-spraying record decks.
 
Quote:

Originally Posted by Argus25 (Post 1203555)
It depends a lot what base metal you are dealing with.

If it is a cast aluminium like metal it can be very difficult to get the new paint to stick well without an etch prime.

That was certainly the case years ago, but with the advent of epoxy primers, it is not an issue. It outperforms all the specialist (and reactive) primers of old. Properly prepared with 120 grit and clean, you will need a dangly grinder to remove it. Steel, aluminium, GRP, plastics, you name it, epoxy primer sticks like the proverbial and is totally inert once cured. It is also very flexible. That means that you don't have to worry about solvent sink or reactions spoiling the finish and it will even work on bumper rubbers etc.

It really is a wonder material, if you have no experience of it, I recommend that
you test it for yourself. It doesn't contain isocyanates, so no special PPE required, even for spraying.

ajgriff 31st Dec 2019 11:56 pm

Re: Re-spraying record decks.
 
1 Attachment(s)
I'd endorse the recommendation to use high temprature paint for spraying aluminium. After some experimentation with various paints I stripped and sprayed the Roberts R505 grille shown in the attached photo with PlastiKote Wood Stove. It needed baking to harden the paint but the outcome is close to the original satin finish and the paint adheres really well. The fact that it initially dries soft, but with good adhesion, also helps greatly when peeling off the modellers' masking tape.

Alan

Boulevardier 1st Jan 2020 1:00 am

Re: Re-spraying record decks.
 
Not too off-topic for this thread I hope, but can any one give any tips for touching-up the engraved (and then 'picked out' with paint) lettering on a metal panel once it's painted?

Mike

rontech 1st Jan 2020 9:13 am

Re: Re-spraying record decks.
 
Quote:

Originally Posted by joebog1 (Post 1201681)
A small trick with spray cans!! Put them in a bucket of hot water before spraying.
This does several things,
1. Thins the paint a little so smaller atomisation.
2. Increases the pressure inside the can, so again better atomisation.
3. Allows thinner coats to be applied.
All the above make for "no orange peel" which is horrible to look at on something we look at very closely.
Spray cans ( good quality ones) are capable of excellent results.

A reasonable time in the hot water is advised!! Too long, or too hot and it may burst
( although I have never seen that happen ).
This was shown to me by an automotive panel beater/spray painter.

Joe

Wise warning!!

Back in about 1961 I worked in a laboratory and was testing the physical properties of aerosol cans for pharmaceutical use. One test involved placing the cans in a temperature controlled very hot waterbath.
A colleague removed one of the cans to apply a pressure gauge to the nozzle, but accidentally dropped the can.

The explosion was deafening, the base flew off the can and hit him in a very sensitive place. It was quite amusing to the others in the lab but the poor chap needed hospital attention.

Argus25 2nd Jan 2020 10:11 am

Re: Re-spraying record decks.
 
Quote:

Originally Posted by Scimitar (Post 1203581)
Quote:

Originally Posted by Argus25 (Post 1203555)
It depends a lot what base metal you are dealing with.

If it is a cast aluminium like metal it can be very difficult to get the new paint to stick well without an etch prime.

That was certainly the case years ago, but with the advent of epoxy primers, it is not an issue. It outperforms all the specialist (and reactive) primers of old. Properly prepared with 120 grit and clean, you will need a dangly grinder to remove it. Steel, aluminium, GRP, plastics, you name it, epoxy primer sticks like the proverbial and is totally inert once cured. It is also very flexible. That means that you don't have to worry about solvent sink or reactions spoiling the finish and it will even work on bumper rubbers etc.

It really is a wonder material, if you have no experience of it, I recommend that
you test it for yourself. It doesn't contain isocyanates, so no special PPE required, even for spraying.

I might have to disagree with you on this. Any surface prepared with 120 grit will adhere to even the poorest quality paint, either lacquer, acrylic or enamel.

The issue is , as pointed out by others, a paint job is no better than the surface it sits on. Unless the paint is abomanably thick & ugly.

For a proper finish it requires the surface is finished to at least the texture seen with 1200 to 2000 grade paper, or either the thick paint masks the scoring from the 120 grade paper or the correct thickness paint shows the scoring from the 120 paper. So you cannot have it both ways.

Al (astral highway) 11th Jan 2020 3:31 pm

Re: Re-spraying record decks.
 
What do people recommend for stripping paint completely? I used to use methylene chloride type stripper but it is not great for the health or environment and I don’t know if we have less noxious but equally efficient agents at our disposal ?

It was banned by the US Environmental Protection Agency (way out of UK jurisdiction , I know, but it suggests how nasty it is)


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