Need help with aldehyde resin synthesized from urea, isobutyraldehyde, and formaldehyde Laropal A81

[willferral]

Hi, I have some laropal A81 which I want to use in a varnish. It is a aldehyde resin synthesized from urea, isobutyraldehyde, and formaldehyde.  I'm wondering if I could catalyze it similar how to Urea Formaldehyde is used in varnish and catalyzed commonly with a acid catalyst.  I've tried  BENZENESULFONIC ACID, 4-METHYL in an amount based of what was used in a conversion varnish product based on it's content of solids of Urea Formaldehyde  and it had very little effect possibly making it softer. It certainly didn't cause  a curing other than by evaporation which you would get with a catalyzed varnish . I tried Phosphoric acid at a much higher amount than would typically be used and it resulted in discoloration and much softer finish ..

 

Does anyone know if this type of resin can be catalyzed and if so, with what?  I've tried contacting the manufacturer but they are an industrial supplier and hard to get ahold of.

 

I hope this is an  appropriate question for this forum? As I'm obviously not a chemist, but I thought  I would give it a try, thanks for any help.

[npts2020]

Welcome to the forum willferral. Unfortunately, I don't know enough about chemistry to help you but there are several people here quite knowledgeable on the topic who might. You did post in the appropriate place.

[willferral]

^ Thanks. 

[exchemist]

On 2/28/2024 at 7:26 AM, willferral said:

Hi, I have some laropal A81 which I want to use in a varnish. It is a aldehyde resin synthesized from urea, isobutyraldehyde, and formaldehyde.  I'm wondering if I could catalyze it similar how to Urea Formaldehyde is used in varnish and catalyzed commonly with a acid catalyst.  I've tried  BENZENESULFONIC ACID, 4-METHYL in an amount based of what was used in a conversion varnish product based on it's content of solids of Urea Formaldehyde  and it had very little effect possibly making it softer. It certainly didn't cause  a curing other than by evaporation which you would get with a catalyzed varnish . I tried Phosphoric acid at a much higher amount than would typically be used and it resulted in discoloration and much softer finish ..

 

Does anyone know if this type of resin can be catalyzed and if so, with what?  I've tried contacting the manufacturer but they are an industrial supplier and hard to get ahold of.

 

I hope this is an  appropriate question for this forum? As I'm obviously not a chemist, but I thought  I would give it a try, thanks for any help.

This is not my area of expertise either, but looking on line, it seems to be an already cured resin, for dissolving in a solvent as a varnish, or as a component in paint  formulations etc.

I thought this site was interesting: https://www.insituconservation.com/en/products/synthetic_resins/laropal_A81. They seem to recommend it as a varnish for conservation of paintings. I can't imagine they would want to add acid curing agents for such purposes. So my guess would be you just dissolve it in a suitable polar organic solvent, apply it and let the solvent evaporate. But that site, in Greece, has a contact page so you might consider asking them if you need a curing agent or whether you just dissolve it and if so what solvent they recommend.  

[StringJunky]

5 hours ago, exchemist said:

This is not my area of expertise either, but looking on line, it seems to be an already cured resin, for dissolving in a solvent as a varnish, or as a component in paint  formulations etc.

I thought this site was interesting: https://www.insituconservation.com/en/products/synthetic_resins/laropal_A81. They seem to recommend it as a varnish for conservation of paintings. I can't imagine they would want to add acid curing agents for such purposes. So my guess would be you just dissolve it in a suitable polar organic solvent, apply it and let the solvent evaporate. But that site, in Greece, has a contact page so you might consider asking them if you need a curing agent or whether you just dissolve it and if so what solvent they recommend.  

AFAIK, from my interest in photography, acidity is the bane of archiving. Acid-free paper and other substrates are used in museum quality work. UV is another one.

Edited February 29 by StringJunky

[exchemist]

1 hour ago, StringJunky said:

AFAIK, from my interest in photography, acidity is the bane of archiving. Acid-free paper and other substrates are used in museum quality work. UV is another one.

That fits, certainly. I suspect this product is the resin already fully polymerised, i.e. the curing step was done during manufacture.  But let's see if the OP comes back and comments.

[willferral]

1 hour ago, exchemist said:

That fits, certainly. I suspect this product is the resin already fully polymerised, i.e. the curing step was done during manufacture.  But let's see if the OP comes back and comments.

I had not thought of it already being fully polymerised. I thought that was the process of joining the formaldehyde with the urea? Or maybe fully cured is what it is?  Typically when a Urea Formeldhye resin gets catalyzed with an acid it becomes solvent resistant. This Laropal one dissolves in just about anything which is why I like it, I can use ethanol which is fairly low toxicity and it dissolves almost as quick as nitro, but I'm concerned my sweat will burn through it  as 1k topcoats have not been strong enough for my usage which on musical instruments and it gets a lot of wear... I want to mix with shellac based on this recipe I found online https://patents.google.com/patent/US3215655A/en and was hoping to use laropal instead of regular Urea Formelhyde which I'm having a hard time finding and also not need aromatic solvents which give off really strong fumes is a major factor.  

 

I was gonna try sulfuric acid which is used in the making of Laropal, but I would probably be wasting my money buying it, lol

 

Thanks for any help

[exchemist]

30 minutes ago, willferral said:

I had not thought of it already being fully polymerised. I thought that was the process of joining the formaldehyde with the urea? Or maybe fully cured is what it is?  Typically when a Urea Formeldhye resin gets catalyzed with an acid it becomes solvent resistant. This Laropal one dissolves in just about anything which is why I like it, I can use ethanol which is fairly low toxicity and it dissolves almost as quick as nitro, but I'm concerned my sweat will burn through it  as 1k topcoats have not been strong enough for my usage which on musical instruments and it gets a lot of wear... I want to mix with shellac based on this recipe I found online https://patents.google.com/patent/US3215655A/en and was hoping to use laropal instead of regular Urea Formelhyde which I'm having a hard time finding and also not need aromatic solvents which give off really strong fumes is a major factor.  

 

I was gonna try sulfuric acid which is used in the making of Laropal, but I would probably be wasting my money buying it, lol

 

Thanks for any help

If you want it for musical instruments I think you maybe ought to consider contacting that Greek outfit and asking. They are in the conservation business, it seems, so pretty close to your sort of application.

But I take your point about sweat when holding an instrument, such as a violin, while performing. You certainly need something that is not weakened or dissolved by sweat. That is a more demanding application than a picture or piece of furniture, certainly.

From looking just now it seems most violin varnishes are traditional, involving things like colophony and linseed oil. There is a lot of stuff about the importance of the varnish not being too rigid or it reduces the sound of the instrument, and issues like that. Well out of my league anyway - I don't play an instrument, only sing. 

[StringJunky]

43 minutes ago, exchemist said:

From looking just now it seems most violin varnishes are traditional, involving things like colophony and linseed oil. There is a lot of stuff about the importance of the varnish not being too rigid or it reduces the sound of the instrument, and issues like that. Well out of my league anyway - I don't play an instrument, only sing. 

If an area is repetitively rubbed, as playing an instrument, no lacquer will survive. Look at any well played guitar. It's the price of playing. Does a person want a musical instrument or a museum piece?  You can't have it both ways. The best instruments have the thinnest and most brittle finishes. How long can that last? I've looked into acoustic guitar making for some years and the issues are the same. I've also had one made and insisted on the thinnest finish and bracing. Both are anathema to durability, but are conducive to good tone, as in expressing the higher frequencies and harmonics. Brittleness of the wood and finish determine how clear and resonant the notes are. 

Edited February 29 by StringJunky

[exchemist]

13 minutes ago, StringJunky said:

If an area is repetitively rubbed, as playing an instrument, no lacquer will survive. Look at any well played guitar. It's the price of playing. Does a person want a musical instrument or a museum piece?  You can't have it both ways. The best instruments have the thinnest and most brittle finishes. How long can that last? I've looked into acoustic guitar making for some years and the issues are the same. I've also had one made and insisted on the thinnest finish and bracing. Both are anathema to durability, but are conducive to good tone. Brittleness of the wood and finish determine how clear and resonant the notes are. 

Sure, it makes perfect sense. One wants maximum resonance from the body of the instrument. I would presume the use of drying oils, such as linseed oil, would help repel the moisture from sweat. 

Which reminds me of that joke in the Molesworth books about the boy not paying attention in a biology class about hibernation: 

Master: "Molesworh, what are you doing? Pay attention. Now, what does a bat do in winter?

Molesworth: "Er....er.......It splits if you don't oil it Sir." 

 

[willferral]

Sorry I play electric guitar on high gain. I'm not super picky in regards to tone of a instrument finish like if it were an acoustic.. I like the feel of shellac on my hand I like a product called post catalzyed shellac but I want to use it over white and his product has amber color, I'm gonna use bleached shellac.  A 2k auto polyurethane like used on the majority of electric guitars is near indestructible and will not wear though from normal use.  I have had no wear issues with the Post cat shellac product I used which is basically a conversion varnish with shellac in it. 

[StringJunky]

3 hours ago, willferral said:

Sorry I play electric guitar on high gain. I'm not super picky in regards to tone of a instrument finish like if it were an acoustic.. I like the feel of shellac on my hand I like a product called post catalzyed shellac but I want to use it over white and his product has amber color, I'm gonna use bleached shellac.  A 2k auto polyurethane like used on the majority of electric guitars is near indestructible and will not wear though from normal use.  I have had no wear issues with the Post cat shellac product I used which is basically a conversion varnish with shellac in it. 

In the UK there is a product called Roberson's CRYSTAL CLEAR 'SHELLAC' VARNISH used for doing gilded objects. It is UV resistant and non-yellowing.

[willferral]

I tested it again, with the dried finish that i put on non stick paper it was cured less than a week, but the stuff that I added acid to dissolved slower than the non acid in acetone.. I had mixed the Laropal with watco brushing lacquer  in about a 70/30 ratio of solids..  I didn't get the results I was looking for with the finish curing in the jar like I thought a 2k would give, and the cured finish  didn't get noticeably harder[ more brittle],   but Maybe I am getting a reaction? I'm gonna try playing around with different percentages of catalyst.

 

The stuff with the catalyst still dissolved pretty quick, but the non catalyst seemed to dissolve almost instantly.

Edited March 1 by willferral
left out words

[willferral]

I tried testing it with shellac but the shellac I bought was bad and didn't dry, so gonna have to stop the testing for now.

[iNow]

Resins are finicky. Their composition matters. Some are good for skim coats whereas others are good for deep pours. Their chemistry and how the user preps govern how they behave.

Curing can go badly with simple things like improper mixing time. I’ve had to stir some for 5-7 minutes to ensure the reaction goes correctly. Proportions of A and B (resin, hardener, etc.) in the mixture need to be super precise.

They’re also sensitive to air temp and humidity levels, especially if those things are fluctuating while it cures. Different products also require specific times between coats, and bonding will fail if the follow-up coat is applied too soon or too late, even if you’ve lightly scuffed the surface for better mechanical bonding. 

You probably know all this already. I don’t know your answer here, but I do know it often matters whether you’re using standard shellac or de-waxed shellac. I always stick (no pun intended) with the latter. 

Edited March 6 by iNow

[willferral]

I've used flakes in the past, some were better than others, but they all eventually worked. I bought bleached shellec for the first time, and had a hard time finding it and ended up buying it from overseas. It arrived  in the mail in a ziplock bag with shellac written in felt marker on the bag.  I put the powder in alcohol over night tried it and it just wont dry. From what I've read on google is that bleached shellac doesn't last as long as regular flake shellac and can go bad pretty quick.

[iNow]

I just buy in a can or (more commonly) in a spray can since I rarely use it and only in special circumstances like when I don’t want paint to bleed into the surrounding wood on carvings
 

[Sensei]

On 2/28/2024 at 8:26 AM, willferral said:

Does anyone know if this type of resin can be catalyzed and if so, with what? 

 

 

[willferral]

On 3/6/2024 at 10:36 PM, Sensei said:

 

 

Thanks for the link I've thought of making my own as it's hard to find these resins for sale, except as ingredients or in powder form in glue, but the resin in the video is a white paste, I need a clear resin and that formaldehyde solution I assume has water in it? I think the water would make it not usable in a shellac ethanol blend even if it was clear?

 

I've actually got a very similar thing to what I'm looking for it's a product sold as a shellac hardener, it's Melamine formaldehyde i think it's in butanol also with extra formaldehyde, but it has a phthlate plastizcer in it which I don't want. Do to the Phthlate I'm not going to use their product its also absurdly expensive.

 

The product is mixed with shellac, looks nice, but not as good as a nitro lacquer Imo, is easy to apply, again not as easy as a nitro lacquer, but since it's almost all ethanol solvent it's usable almost anywhere without stinking up my apartment.