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 Post subject: Don't want to Strip - How to proceed
PostPosted: Mar Thu 26, 2020 1:20 am 
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Joined: Mar Fri 11, 2016 9:20 pm
Posts: 64
Hey guys. I've got a Firestone Air Chief S-7397-9 that I am restoring. The finish is very fragile, and it's easily scraped off with a fingernail. Would the application of fresh spray lacquer rejuvenate it? My goal is to not have to strip it so I can preserve the silk screen/decal labels on the cabinet. I am willing to strip it though if need be.

Secondly, the dial plastic is pretty dingy but I'm concerned that any attempt to clean it may cause the lettering to come off. Any suggestions there?

The knobs and buttons were all warped and semi-melted looking. Weird. I'm going to model them to the best of my ability and make 3d-printed replicas. It'll be my first opportunity to use that for anything radio related.

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 Post subject: Re: Don't want to Strip - How to proceed
PostPosted: Mar Thu 26, 2020 2:46 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 9153
Location: 13 Critchley Avenue, PO Box 36, Monteith Ont, P0K 1P0
JasonWatkins wrote:
........... Would the application of fresh spray lacquer rejuvenate it? ........



I think this is known as "reflowing". Some people have had good success doing this. I've never tried it. If you are searching for results, use the search term "reflowing".

cheers


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 Post subject: Re: Don't want to Strip - How to proceed
PostPosted: Mar Thu 26, 2020 4:15 am 
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Joined: Nov Mon 05, 2007 11:08 pm
Posts: 3030
Location: Calgary Alberta
This is just me talking, but I would strip it, and start over.
You can get decals from Radio daze
https://www.radiodaze.com/reproduction-graphics/

I realize that everyone does not want to do cabinet work,and each to his own, but you are asking for opinions.
There are a lot of guys in the forum who don't do cabinets and that is OK.
I have not tried to reform lacquer and it might work quite well.
Personally I like to refinish cabinets
Dan in Calgary


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 Post subject: Re: Don't want to Strip - How to proceed
PostPosted: Mar Thu 26, 2020 4:25 am 
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Joined: Mar Fri 11, 2016 9:20 pm
Posts: 64
I'll check out reflowing. I had never heard of that before.

I've re-finished several cabinets in the past so it's not out of the question. Traditionally, I used wipe on polyurethane. It's a pain to get smooth but it can be made to look nice with some patience. I got an HVLP sprayer some time back though and have had a lot of luck with lacquer. I actually like it a lot. Now, I have gotten decals and two magnificent phenolic replacement dials from RadioDaze before. I couldn't get those decals to look good to save my life...even with the judicious application of profanity. I'll probably attempt to reflow it and see how it does. I'd have to strip it anyway so it won't hurt to try.


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 Post subject: Re: Don't want to Strip - How to proceed
PostPosted: Mar Thu 26, 2020 5:09 am 
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Location: S. Dartmouth MA 02748-1225 USA
The finish is dead, if it is re-flowed there may not be complete "smoothout " of the color. Much of the finish color is not stain but a dye in the lacquer. I would not strip nor would I clear lacquer re-flow. I would look to the Howards Restore-a-Finish product. This product is intended to be hand applied containing solvents, retarders (so it will stay fluid enough during application), a base of tinted lacquer. If applied by the instructions and the correct color chosen it will renew the old finish by re-amalgamating and lay down a new surface. Once hardened it can be lightly buffed and clear lacquer applied. The benefits go beyond, the near original color, filler will be preserved. If there was any OEM overspray toning, that that would be blended in, this radio seems to look like that is not the case.

Oh, there is an investment in learning and elbow grease not as easy as sprayon and dry... :roll:

YMMV

Chas

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 Post subject: Re: Don't want to Strip - How to proceed
PostPosted: Mar Thu 26, 2020 8:14 am 
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Joined: Mar Fri 11, 2016 9:20 pm
Posts: 64
That's something else that I have never heard of. They're saying that it's available at my local hardware stores too. I'm not afraid of a little elbow grease. It's just that I've had to strip off decals before and I just hate doing it. My Moto 6y probably has close to 20 very thin coats of diluted poly on it. Buffed with a scotchbrite pad between each one. I just wanted the grain to be filled without visible brush strokes. It's a challenge but it can be done. Not that I claim to have any particular level of talent.


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 Post subject: Re: Don't want to Strip - How to proceed
PostPosted: Mar Thu 26, 2020 4:27 pm 
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Location: S. Dartmouth MA 02748-1225 USA
Practice on furniture scraps first. That, will also confirm the coloring... May be able to re-amalgamate with the product by carefully padding around the decals. If not take razor sharp images, with a digital camera at high resolution, use a 50mm lens, shorter or longer lenses or a cellphone lens with have noticeable distortion. Tripod, inverted and square-on will eliminate parallax. The digital image file can be massaged, repair breaks or correct for other distortions to some degree and used to generate a water slide decal, yes, a decal with metallic are hard to do but there are workarounds...

You may have to get a can of toner, either opaque or transparent. That will depend how damaged the trim sections are. Toner is used for both accent and hiding lesser woods with plain grain.

Essentially, what is happening is the use of furniture repair touch/up techniques. There are online tutorials for such skills...

The issue with "poly" is it has a different curing system. The cross linking that takes place is permanent and no common solvent can break the chains and either bind another coat or easily dissolve it. There-in successive coats lay on top or each other and are not amalgamated to each. Over a long period of time all poly yellows from the effects of UV and unequal shrinkage of each layer. I have seen this on the few household poly surfaces in my home. The windows are now framed in deep orange and the sills are peeling. Even varnish has this problem as it has a similar cross linking system. Older radios used fine furniture finishing techniques.

Another observation, even with re-amalgamating, is while the failed finish is in place, a staining furniture polish like "Old English" was used of a darker color. What will happen is veins of darker color will be in the wood, that are not removable in a normal re-amalgamating and will be sealed in. If that is not objectionable then O.K.

Radio was a center of attraction in the home, warm wood tones and bright glowing grain was the appeal. Over time UV also takes its toll, not only darkening the lacquer, but bleaching the red toning out leaving a greenish tint and oxidizing the wood underneath for a few thousands of an inch. The becomes grayish and no longer sparkles from its grain fiber. A full strip also includes sanding the wood to return color by removing the dead layer. That also means filling the new open pores, staining, sealing the the progressive topcoats and toning.. Result is the beauty is returned as it was using only 2 to 4 top coats depending on the wear surface, sides vs top...

There is one other sneaker, the use of silicone based polish. Silicone will cause "fish-eye" in a project unless retarders are used and the finish stripped down and the wood sanded. FWIK there are retarders in the Howard's product.

YMMV

Chas

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 Post subject: Re: Don't want to Strip - How to proceed
PostPosted: May Mon 04, 2020 7:51 am 
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Joined: Mar Fri 11, 2016 9:20 pm
Posts: 64
Well, this is what I wound up doing. I went ahead and stripped it. Red Mahogany stain and about eight coats of semigloss lacquer. I didn't want to chance decals so I just designed and 3d-printed knobs that have embossed lettering on them. It works excellently as well.


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 Post subject: Re: Don't want to Strip - How to proceed
PostPosted: May Mon 04, 2020 9:40 pm 
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Location: Paducah, Ky
That turned out great! I bet you are glad you did it now. Great job.

Dwayne

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 Post subject: Re: Don't want to Strip - How to proceed
PostPosted: May Tue 05, 2020 7:33 pm 
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Joined: Dec Tue 20, 2016 6:33 pm
Posts: 63
I have has some luck re-flowing with lacquer thinner this way: First check in a discrete spot whether the finish reacts badly to lacquer thinner. Then clean the existing finish with a non-residue cleaner to get any surface dirt off. Then spray 2-3 coats of lacquer thinner onto the finish, hitting it with enough thinner to see a gloss each time. If it still looks bad start adding some lacquer to the the gun.


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 Post subject: Re: Don't want to Strip - How to proceed
PostPosted: May Wed 06, 2020 2:42 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 11448
Location: Baguio City, Philippines
This radio wasn't a good candidate for a reflowing process to begin with. With the finish flaking off, it would be impossible to properly clean the surface, which is essential in keeping dirt out of the final finish. Since radio cabinets use colored (toned) lacquer, reflowing cannot be used on sets that have large areas of missing finish as the reflowing process won't recreate a color the isn't already present.

Reflowing lacquer (also works with shellac finished if you use denatured alcohol) is best utilized when there are surface issues with the old finish, such as cracks or rough sections. The theory is simple: You add a solvent to the original finish, the solvent liquifies the finish, and then gravity causes it to flatten out. The solvent then dries and the finish is smooth like it was originally.

In practice you need to clean the surface first to rid it of any dirt, waxes, or oils. The best way to do this is too use naphtha (labeled VM&P Naphtha in a paint store). This will remove all the bad stuff, but won't affect the finish or the wood. This is what furniture restorers use. Mineral Spirits can be substituted as it's chemically similar. The drying time of Naphtha makes it easier to use.

After the dirt is removed it's time for the reflowing part. Lacquer thinner is the solvers for lacquer, but it evaporated too quickly to be really effective. One needs to slow down the solvent evaporation, and that is done by adding a product called lacquer retarder. Retarder is commonly added to lacquer when spraying conditions are less than optimal to prevent lacquer "blush" on humid days. Lacquer dries by evaporation o the solvents and the surface dries first, skinning over, and that can trap moisture underneath which shows up as a whitish haze. This issue is resolved the same way as the reflow process, by the addition of a thinner/retarder mixture to liquify the finish and let it dry again.

If you have spray equipment, you can make this mixture by combining 1 part lacquer retarder with 3 parts of lacquer thinner. This same mixture is avail in spray can and is called various things like Blush Eliminator , Blush Eraser, or Lacquer Leveler.

The process is simple:

Clean the wood.
Place one surface so it is level, facing up.
Liberally spray on a coat of blush eliminator.
Let it dry.
Spray on additional coats of lacquer, if desired.*
Rub out the finish to the gloss level desired.

It's that simple to do. It's a good trick to have in your arsenal of techniques, and one that doesn't require a lot of practice or skill to utilize. It isn't something that you probably will use very ofter, as the set of circumstances it fits is rather narrow.

* I usually add one or two coats of clear lacquer over the repaired finish as insurance the the lacquer layers are thick enough to work with. Since the additional lacquer is clear and a don't do a lot of layers, it doesn't change the appearance of the finished product.


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 Post subject: Re: Don't want to Strip - How to proceed
PostPosted: May Wed 06, 2020 1:18 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1170
Location: St. Louis, MO, USA
I usually try to keep the original finish whenever possible by similar methods mentioned above. It’s nearly impossible to recreate the original finish in my experience.

Dennis


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 Post subject: Re: Don't want to Strip - How to proceed
PostPosted: May Sun 10, 2020 5:46 am 
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Joined: Mar Fri 11, 2016 9:20 pm
Posts: 64
I have another radio that I'll probably try to re-flow. I do have an HVLP gun. I used it on this radio. I don't have much experience with the finer points of lacquer application though. I've never used toner or any additives. I can't even buy any of it locally. There's a Sherwin Williams in town and they stock a great deal of the stuff, but since I'm not a "pro", I get to pay $80 per gallon for it. I haven't been back since I found that out. I have only had TERRIBLE experiences with shellac.. Good lord I have nearly ruined a couple of pieces while attempting to use it. I used to use wipe-on polyurethane with a foam brush and some foul language. It is an absolute pain getting a nice and smooth finish (at least for me) but great results can be had with a lot of patience. The sprayer has me spoiled though. I'll never go back. Anyway, thanks for the help. I'm going to attempt to apply the advice given here on my next project. It's more of a cheapo 1950s AM/FM GE tabletop. This is a mothers' day present for my mom. She bought it at a yard sale for $15 and remarked that she'd like to have one.


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 Post subject: Re: Don't want to Strip - How to proceed
PostPosted: May Sun 10, 2020 7:37 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 11448
Location: Baguio City, Philippines
Shellac has to be thinned considerably before application. Also, it has a limited shelf life of approximately a year, after which time it won't seem to dry properly. You can easily remove shellac with a rag wet with alcohol.

A "piano finish" is shellac, applied using a method called French polishing that builds up extremely thin layers that melt into each other.You can make a beautiful, highly reflective, glass smooth surface easily using shellac. shellac was a not uncommon finish in the 1920's. The popularity of lacquer because of it's quick drying time and resistance to damage, saw the decline in its popularity.

Although fairly easily damaged, shellac finishes can usually be repaired easily.


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