Hardener in paint

Mon Jan 30, 2012 2:00 pm

I'm aware of most of the warnings and concern by fellow members about using a supplied-air breathing apperatus while using hardener.

My queston: Once the hardener was added to the paint, if painting outdoors, do you still need a supplied-air breathing apperatus or could you use a paint respirator like this?

http://www.homedepot.com/h_d1/N-5yc1v/R ... ogId=10053

Follow-up question: Has anyone tried using IH Case 2150 red with a reducer other than IH Case? I found this post:


This one turned out great--but it also had hardener.

Let me know your thoughts...

Re: Hardener in paint

Mon Jan 30, 2012 2:15 pm

I am certainly no expert in this area, but my brother-in-law is a painter and he told me that when using a hardener I should make sure I have good ventilation and use a activated charcoal respirator.

Regarding the IH Case paint, yes I used a reducer other than IH Case with no problems. Any enamel reducer should work with the IH paint.

Re: Hardener in paint

Mon Jan 30, 2012 2:23 pm

I use hardner in all my paints.
Example: IH 2150 red I use a hardner from Valspar and Dupont 3812 Enamel reducer. I really don't measure it exactly either. I have a Air purifying respirator that I wear regaurdless of what I spray, indoors or outdoors. I do make sure I have a fan at my back though making sure all fumes are pushed away from me. I will try and find a pic of my mask, I cost me like $60 at the paint store.

Re: Hardener in paint

Mon Jan 30, 2012 2:32 pm

Do you need supplied air while painting outside? Depends on what level of risk you are willing to take. I paint outside both with and without a hardener and never use supplied air and typically do not use a mask.

There are or used to be canisters for isocyanates and it seems like an organic charcoal filter would work but the data I could find several years ago shows the charcoal filters not very effective for isocyanates. Not sure why that would be but apparently is true.

What level of risk do you want to take? The least risk is supplied air even outside. How long should you leave the mask and hood on after painting, when does removing the hood NOT spread residual isocyanates, what happens to the area downwind from you spray site? Are folks downwind exposed to significant isocyanates and what is a significant exposure? I did not find many consistent answers several years ago when I was looking into exposure levels.

Isocyanates have both a dosage effect, the more you are exposed, the more likely certain things will happen. It also has a non-dose related response, one exposure can potentially cause bad things to happen. That is the part that should worry the average hobbiest.

I have no allergies to anything that I know of, no poison ivy, asthma, seasonal allergies, and my research interest in grad school years ago was isocyanates, so I am not concerned for myself. Folks with atopic, asthma, ect.. should be concerned, others likely should be concerned given the lack of a screening test for the non-dose related response. Being outside will not limit that non-dose related response.

EDIT: Should have said...being outside without supplied air will not eliminate the risk of a non-dose related response....
Of course, being outside will lower the total exposure.
Last edited by Landreo on Mon Jan 30, 2012 2:51 pm, edited 1 time in total.

Re: Hardener in paint

Mon Jan 30, 2012 2:44 pm

The problem with cannister filters is that very few have an indicator telling when they need to be replaced. As Larry indicated, you don't know when your individual threshold will be reached and once it is passed, it's too late.


Re: Hardener in paint

Mon Jan 30, 2012 3:33 pm

I use a very high quality mask that we keep here at the plant for our batch plant operators to wear. I know it filters very fine silica particles and not fumes...but it's my best reasonable attempt. I paint in my shop with the doors open and forced air in and out...not really a controlled environment like some do. I try to be careful and I figure painting once a year probably don't do me anymore harm than the occasionally box of Swisher Sweets or Philly Chocolate Blunts ... :)

Re: Hardener in paint

Mon Jan 30, 2012 7:00 pm

isocyanates are so fine they pass right through the charcoal filter. Definitely not something to mess with.

If you can bear to wait the 30 days, the paint will be fully cured.

Re: Hardener in paint

Mon Jan 30, 2012 10:08 pm

He has not been up to posting lately, but many of us who have been around for a while remember George Willer, who was in my opinion one of the mot knowledgeable people around. He had COPD, much of which was the result of painting and using hardener. Here are some of his comments about hardener:

George Willer wrote:
papermaker wrote:So what I have gathered is not to use a hardener because of health concerns. Correct? Would it be safe if I used just the paint/thinner as long as I use a respirator ? What would be the recommended respirator?

You have the idea! Of course the hardener makes the paint harder... and also makes it a bit easier for a novice to use. Here's the bottom line... I'd trade all the tractors I've painted for a good set of lungs. Hardener isn't really necessary for a good paint job.

Here are some of my early paint jobs...


George Willer wrote:
Landreo wrote:The paint I typically use is not 8:1. Inexpensive alkyd enamels may be but acrylic and urethane may not be. The arylic enamels I use are 8:2:1 ratio. Check with the manufacturer for sure. Hardeners are not as lethal as some would have you to believe but you may be the one who is allergic or suseptable to pulmonary fibrosis. Play it safe if you are not a risk taker. if you are concerned about your health when using hardners then you also should be concerned about your family and neighbor's health. They also may be exposed to fumes and overspray while using hardeners.

That's what I thought too. It's like playing Russial roulette... and I lost. :( There's no way to know until it's too late. That's why I now spend a lot of time (like right now) breathing medication from a nebulizer so I can keep on breathing.


George Willer wrote:
annaillinois wrote:Thanks guys i will ponder on this a bit and probably just go with the paint without the hardener.


Good for you, Terry! As one who suffers from serious lung disease, I can tell you the advantages of using hardener aren't worth the health risk just to have a shiney paint job. There are paints such as IH 2150 that don't really need hardener and can result in a show quality product.

George Willer wrote:Barney,


I had to learn the hard way. The medications I have to use cost a small fortune just to keep breathing. No more hardener here... EVER!

Charcoal filters are worthless for use with modern paints. :(

There are many similar comments from George, but no need to go on and on, so I will end with this one from Don McCombs, who if I remeber correctly may have been a professional painter.

Don McCombs wrote:George is absolutely correct. The charcoal filters will NOT protect you from VOC's or isocyanates. They filter only particulates. Use ONLY a supplied air system with a mask and hood. Your lungs aren't the only port of entry for these contaminants. Don't risk your health for a few dollars. If you don't want to buy the right equipment, have someone else do the painting.

Re: Hardener in paint

Mon Jan 30, 2012 10:34 pm

I have a new paint gun tucked away, nothing fancy, just a Sears Craftsman. I have never tried to use it, read some of the stuff on the WWW about the dangers of the fumes and got sort of freaked out. I would like to one day learn how to paint, at least well enough to do some of my own restorations. Assuming one wanted to use hardener, exactly what sort of PPE do you need to be safe?


Re: Hardener in paint

Mon Jan 30, 2012 10:54 pm

Al, I bought a "shoot suit" that is a lightweight coverall with elastic cuffs. I use Nitrile gloves for their chemical resistance and toughness. Most importantly I bought a remote air supply set up with a fabric hood and 100 feet of hose. The hose comes up over your head and blows air down your face. It is clunky but effective. You can find them on eBay for $3-400. They are ok for amateur use but if I were using one every week I would get a pro setup for a lot more money mainly to have something with better visibility.
It is my understanding that a charcoal canister will work for iso's but only for a short time. If the charcoal gets saturated and you smell solvents, it is far too late. I use the charcoal respirator for mixing the paint and change the canisters every day.

Here is an example. Better ones have a fitted rubber full face mask and cost more. Make sure the mask fits. Always go for a full-face protection. Your eyes and skin suck the chemicals right in.


Re: Hardener in paint

Tue Jan 31, 2012 12:00 am


Let me add a few comments.

I have been finishing with multi-part catalytic s for decades and using what respirators that I could afford and of course what was available at that time. I wish better equipment could have been available back then.Today I suffer from COPD and PF. Is some of it related to my spraying finishes... probably. But who really knows for sure. It is like smoking. We now know that it is a carcinogen and is hazardous to our health yet 50 years ago Doctors were advertising the beneficial effects of cigarettes... :big give up:. So this is my take on it.

Since we have affordable externally supplied systems as well as affordable SCBA's it makes no sense what so ever to take a chance with your health. Although the respirator may and I repeat may meet minimum standards it is predicated on the proper use of said systems. Like the old Scott Air Paks -- that means no facial hair and all them kinda rules. The equipment today is far superior to what was available even 5 years ago. This would also assume best case scenarios which btw very seldom apply.

I can say this, if I knew then what I know now I would never have used only a dual filter respirator even though I had a high volume air extraction system. I would have found the money to purchase the best ESBA or SCBA that I could afford.

Living with COPD and PF is not fun and it definitely is not a worthwhile risk to take just to save a few bucks. My attitudes have changed an awful lot in the last few years..... :roll: Sherwin Williams if I remember the catalog entry about 2 years ago, has a good ESBA for around $150.00 or so.. I would check it out.

Re: Hardener in paint

Tue Jan 31, 2012 8:25 am

All--you have MORE than answered my question. Thank you for reminding us of the dangers.

Each has to do as they see fit, but as for me, I'll probably stick to 2150 enamel with reducer/thinner. That's what I used to paint Nellie and I think she turned out fine:


Thanks again! I'll just be extra careful not to spill gas on the paint!!

Re: Hardener in paint

Tue Jan 31, 2012 8:31 am


Rudi is dead on. I never smoked and yet at 49 I found out I had COPD/Ashtma. The cost of the med's to keep me breathing far out pace the cost of the best protection you could buy. I painted very little with an air gun but one time is all it takes.

Re: Hardener in paint

Wed Feb 01, 2012 8:49 pm

What I pay for COPD/asthma medication in a month will pay for a really nice respirator. Inside or outside why risk it. If you dont have breathing problems then protect your lungs.

Re: Hardener in paint

Thu Feb 02, 2012 7:20 pm

if you use a GOOD double filter charcoal resperator you shoud be fine. I have been painting for 40 years with no problems. Keep in mind that if you paint outside you should still use a resperator. :idea: depending on how you heat your shop is a issue too. If you heat with any open flame or wood stove you need to have good ventilation or you will find your shop in a million pieces.