Denatured Alcohol, Rubbing Alcohol

[Mustang67]

Is denatured Alcohol necessary for cleaning fiberglass prior to using epoxy? Or can I just use Rubbing Alcohol?

 

[Rob702Martinez]

I have and still use both, I can't see a difference. I do use wax/grease remover always prior though. 91% alcohol though

 

[manixFan]

What's funny is if you read the FAQ on the JB Weld website if very specifically says NOT to use alcohol: (from their website)

"What can I use as a surface cleaner before using J-B Weld?
We recommend using acetone or lacquer thinner. In the absence of these two, soap and water can be used. Just be sure that the surface is completely dry before applying J-B Weld. DO NOT use alcohol or any “cleaner” that will leave a petroleum residue."

(I agree that statement does not make a lot of sense as lacquer thinner has a lot of petroleum products in it.)

West Systems says:

"Clean contaminated surfaces with lacquer thinner, acetone or other appropriate solvent. "

System Three (what I use) says:

"Prior to sanding wipe away any oil or grease with a clean rag and suitable solvent"

So not really sure about using alcohol to clean. I typically use acetone since it evaporates so quickly. Normal rubbing alcohol is 30% water which means you have to make sure the surface has dried before applying the epoxy.


Tony

 

[Dave A]

I keep a gallon of denatured in the shop for cleaning everything.
I prefer not to use acetone or lacquer thinner due to the effects of prolonged use.

 

[UhClem]

Is denatured Alcohol necessary for cleaning fiberglass prior to using epoxy? Or can I just use Rubbing Alcohol?

Rubbing alcohol frequently contains other ingredients which are not compatible with a good bond. Check the ingredient list.

 

[crossfire]

I use alcohol but you need to get alcohol in the 90 plus percent range. Walgreens sells it.

 

[KarlS]

Rubbing alcohol contains a small percentage of oil for lubrication. Denatured does not. Denatured alcohol can be used to thin epoxy so it can be brushed on.

 

[cvanc]

Yeah, rubbing alcohol is made for rubbing - you know, massage. As such it usually contains oils or perfumes or other things that make for a good massage but would definitely NOT be good for use as a cleaner.

These additives would contaminate any surface you were trying to clean.

 

[rocketguy101]

Isopropyl Alcohol is the same family as rubbing alcohol, but without the oils, I believe.... I get 91% at walmart, walgreens, etc

 

[Nytrunner]

Isopropyl Alcohol is the same family as rubbing alcohol, but without the oils, I believe.... I get 91% at walmart, walgreens, etc

^^ When in doubt, IPA

 

[patelldp]

^^ When in doubt, IPA

Got it.

 

[Woody's Workshop]

Paint prep cleaners are nothing more than high grade mineral spirits.
Don't use paint thinner or low grade mineral spirits with the strong bad smell. That will leave a residue.
I personally use lacquer thinner, but most of my stuff is on plastics so I'll wipe it down with mineral spirits and a quick wipe with lacquer thinner.
Have to be quick because puddling or too long of exposure will melt the plastic.
Lacquer thinner is completely safe to use on fiberglass, carbon fiber or any other cured material.
If your using acetone, ware gloves! That stuff is wicked on the body.

 

[cvanc]

The two wisest things in this thread:

Dan's beverage recommendation

Woody's reminder to always wear gloves when using acetone

Carry on! :grin:

 

[crossfire]

Yes rubbing alcohol is not what I use.

 

[cvanc]

Isopropyl Alcohol is the same family as rubbing alcohol, but without the oils, I believe.... I get 91% at walmart, walgreens, etc

Exactly. The other 9% in the commonly found 91% pure variety is just water. This is the good stuff.

(sold, as I understand it, for people to have to give themselves shots and need to sterilize their injection sites, like diabetics and such)

 

[manixFan]

Rubbing alcohol frequently contains other ingredients which are not compatible with a good bond. Check the ingredient list.

So I did check the ingredient list on the 3 different bottles of rubbing alcohol I have around the house and all list only water as the other ingredient. Curious, I got on the web and did a google image search on 'rubbing alcohol labels' and the only time something other than water was listed was if it had a small amount of methyl salicylate (wintergreen oil). This was looking at about a pretty wide variety of labels. So unless the labels are wrong, the majority of rubbing alcohol sold is just alcohol and water, nothing else.


Tony

 

[Lowpuller]

I have to admit, I have used acetone for years without using gloves.

Same thing as fingernail polish remover. It will definitely dry your skin out.

Not recommending, just noting.........

 

[Mustang67]

Thx All!

 

[OverTheTop]

I use MIBK for wiping down prior to epoxy bonding on fiberglass.
https://en.wikipedia.org/wiki/Methyl_isobutyl_ketone
Remember PPE when using this, and in a well-ventilated area.

I also use IPA if I am not too fussy.

 

[soopirV]

Yeah, rubbing alcohol is made for rubbing - you know, massage. As such it usually contains oils or perfumes or other things that make for a good massage but would definitely NOT be good for use as a cleaner.

These additives would contaminate any surface you were trying to clean.

Is THAT why it's called rubbing alcohol? I've wondered that for 30 years...obviously never enough to look into it, but hey, makes sense!

 

[gpoehlein]

Isopropyl Alcohol is the same family as rubbing alcohol, but without the oils, I believe.... I get 91% at walmart, walgreens, etc

Kind of the other way around - rubbing alcohol is usually isoprpyl alcohol with additives. Quick chem lesson - methyl alcohol (methanol or wood alcohol) has one carbon atom and is quite poisonous. Ethyl alcohol (or ethanol) is the drinking kind and has two carbon atoms. Denatured alcohol is ethanol with something like a bit of methanol added to make it undrinkable. Isopropyl alcohol is one of two kinds of propanol, which has three carbons, and the alcohol OH is connected to the center carbon. If you attach it to an end carbon, it becomes n-propanol, which actually has different properties than isopropyl. The interesting and really useful trait of alcohols is that the can both act as an organic solvent as well as an ionic (water soluble) solvent. Yeah, I know - way more info than you wanted!

 

[cvanc]

Is THAT why it's called rubbing alcohol? I've wondered that for 30 years...obviously never enough to look into it, but hey, makes sense!

(tips hat) I live to serve, sir! :handshake:

 

[Woody's Workshop]

Good stuff!
Always like learning something new.
Thanks for sharing your knowledge.

Kind of the other way around - rubbing alcohol is usually isoprpyl alcohol with additives. Quick chem lesson - methyl alcohol (methanol or wood alcohol) has one carbon atom and is quite poisonous. Ethyl alcohol (or ethanol) is the drinking kind and has two carbon atoms. Denatured alcohol is ethanol with something like a bit of methanol added to make it undrinkable. Isopropyl alcohol is one of two kinds of propanol, which has three carbons, and the alcohol OH is connected to the center carbon. If you attach it to an end carbon, it becomes n-propanol, which actually has different properties than isopropyl. The interesting and really useful trait of alcohols is that the can both act as an organic solvent as well as an ionic (water soluble) solvent. Yeah, I know - way more info than you wanted!